Discussion:
Mojave airport is not a spaceport
(too old to reply)
Andrew Nowicki
2004-06-19 21:10:08 UTC
Permalink
The Mojave Airport is a perfect place to test
airplanes and sounding rockets, but it is probably
the worst place on Earth to locate the space rocket
launch site -- Manhattan would be better. There is
no ocean to the east of Mojave, so you cannot make
cheap pressure-fed rockets, splash them down and
reuse them. A big city (Los Angeles) is just 100 km
south of Mojave. The nearest pacific coast is 130 km
south west, next to Ventura, California. If you
launch the real thing, you will have to launch it
in the south west direction and hope it will not
fall on Los Angeles.

NASA should make the Kennedy Space Center available
to independent rocket makers.
Alan Anderson
2004-06-19 22:16:32 UTC
Permalink
Post by Andrew Nowicki
There is
no ocean to the east of Mojave, so you cannot make
cheap pressure-fed rockets, splash them down and
reuse them.
If you're going to reuse them in any significant fashion, "cheap" is a
loaded term. You want them to be economical to use, certainly, but that's
not the same thing as being inexpensive to build (or buy) in the first
place.

I've always agreed with the idea that dropping machinery in saltwater and
fishing it back out isn't a great thing to do if you want to use it again
without significant refurbishing. What's wrong with spending the bit of
extra effort required to simply *land* the things and reuse them?
Appropriate up-front engineering can lower the operational costs of
staging. A lot of cost can be saved if your first stage rocket comes back
to the launch site by itself, and if it basically just needs to be brushed
off and recharged/refueled before it's ready to have an upper stage
vehicle latched on for the next launch.

(For that matter, what's wrong with spending the next bit of extra effort
required to make "first-stage rockets" as quaint as capsule splashdowns?
The ultimate reduction in the operational costs of staging is to remove
staging completely.)
Perplexed in Peoria
2004-06-19 22:52:41 UTC
Permalink
Post by Alan Anderson
(For that matter, what's wrong with spending the next bit of extra effort
required to make "first-stage rockets" as quaint as capsule splashdowns?
The ultimate reduction in the operational costs of staging is to remove
staging completely.)
To eliminate staging, you need to provide:
1. Enough extra wing to land the big "first stage" tanks.
2. Enough extra shielding to re-enter tanks and wing.
3. Enough extra fuel to deorbit tanks, wings, and shielding.
4. Enough extra fuel to get tanks, wings, shielding, and
extra fuel into orbit in the first place.
5. A larger "first stage" tank to hold the extra fuel for
requirements 1-4.
6. And so it cycles.

These requirements don't go away with a "bit of extra effort"
at the design and manufacturing stage. Maybe eliminating
staging saves enough operationally to make sense. But maybe
we should be trying to cut those operational costs without
resorting to fundamentally wasteful expenditure of resources
lifting and returning things that we don't use while we are
"up there".
Alan Anderson
2004-06-20 05:02:21 UTC
Permalink
Post by Perplexed in Peoria
1. Enough extra wing to land the big "first stage" tanks.
Wet wings can help here. But who says you need wings in the first place?
Post by Perplexed in Peoria
2. Enough extra shielding to re-enter tanks and wing.
You're talking thermal protection, right? If the vehicle is big and light
at reentry, dealing with the heating problem should be *easier*.
Post by Perplexed in Peoria
3. Enough extra fuel to deorbit tanks, wings, and shielding.
4. Enough extra fuel to get tanks, wings, shielding, and
extra fuel into orbit in the first place.
5. A larger "first stage" tank to hold the extra fuel for
requirements 1-4.
Fuel is cheap.
Post by Perplexed in Peoria
6. And so it cycles.
If you start with something large enough to meet the requirements in the
first place, you don't have to iterate making it larger.
Post by Perplexed in Peoria
These requirements don't go away with a "bit of extra effort"
at the design and manufacturing stage. Maybe eliminating
staging saves enough operationally to make sense. But maybe
we should be trying to cut those operational costs without
resorting to fundamentally wasteful expenditure of resources
lifting and returning things that we don't use while we are
"up there".
Those "resources" are essentially propellant. Wasting something that
isn't all that expensive is not a large problem.
Henry Spencer
2004-06-20 03:01:36 UTC
Permalink
...Maybe eliminating
staging saves enough operationally to make sense. But maybe
we should be trying to cut those operational costs without
resorting to fundamentally wasteful expenditure of resources
lifting and returning things that we don't use while we are
"up there".
The question is whether it is less trouble to take them along, or to have
them fall off and be recovered separately. The answer is not immediately
obvious. Recovering stuff that falls off halfway to orbit is not easy.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert | ***@spsystems.net
Ian Stirling
2004-06-20 17:54:37 UTC
Permalink
Post by Henry Spencer
...Maybe eliminating
staging saves enough operationally to make sense. But maybe
we should be trying to cut those operational costs without
resorting to fundamentally wasteful expenditure of resources
lifting and returning things that we don't use while we are
"up there".
The question is whether it is less trouble to take them along, or to have
them fall off and be recovered separately. The answer is not immediately
obvious. Recovering stuff that falls off halfway to orbit is not easy.
If you'r recovering them significantly before halfway to orbit, then
it becomes a little easier.
Your stage may only be a few tens to a few hundred kilometers downrange, and
the velocity it's coming in at is only single digit Mach numbers.

You don't tend to need much thermal protection, and ensuring it always hits
ocean near your recovery vessel is probably easier.
Then again, the benefits are smaller.
Andrew Nowicki
2004-06-20 18:35:36 UTC
Permalink
Henry Spencer wrote:
HS> The question is whether it is less trouble
HS> to take them along, or to have them fall off
HS> and be recovered separately. The answer is
HS> not immediately obvious. Recovering stuff
HS> that falls off halfway to orbit is not easy.

This is a very interesting topic, because it is
the essence of cheap access to space. Most rocket
launchers are disposable because they cannot
survive the reentry. The nose cone of the Space
Shuttle heats up to 1460 degrees Celsius during
reentry. 1460 degrees Celsius is about 1200
degrees above ambient temperature. How much would
the nose cone heat up if the reentry velocity
was reduced by half? My guess is that the nose
cone temperature would be 1/4 of 1200 degrees
above ambient temperature, or about 300 degrees
Celsius. That is not bad! I believe that structural
stress is much bigger problem for the flimsy tanks
of the pump-fed rockets. This is another argument
in favor of the sturdy, pressure-fed rockets.

______________________________________________________


Ian Stirling wrote:
IS> If you'r recovering them significantly before
IS> halfway to orbit, then it becomes a little easier.
IS> Your stage may only be a few tens to a few
IS> hundred kilometers downrange, and the velocity
IS> it's coming in at is only single digit Mach numbers.

But then your launcher has three stages instead of
two
Paul F. Dietz
2004-06-20 19:37:04 UTC
Permalink
Post by Andrew Nowicki
HS> The question is whether it is less trouble
HS> to take them along, or to have them fall off
HS> and be recovered separately. The answer is
HS> not immediately obvious. Recovering stuff
HS> that falls off halfway to orbit is not easy.
This is a very interesting topic, because it is
the essence of cheap access to space. Most rocket
launchers are disposable because they cannot
survive the reentry. The nose cone of the Space
Shuttle heats up to 1460 degrees Celsius during
reentry. 1460 degrees Celsius is about 1200
degrees above ambient temperature. How much would
the nose cone heat up if the reentry velocity
was reduced by half? My guess is that the nose
cone temperature would be 1/4 of 1200 degrees
above ambient temperature, or about 300 degrees
Celsius. That is not bad!
The rate of energy flow in the air stream, at a given
density, is proportional to the cube of the velocity.
If we very naively assume the heat rate on the nose cap
is proportional to this, and that it cools by radiation
(at a rate proportional to the fourth power of absoluete
temperature), then the absolute temperature of the nose
cap should scale as velocity^(3/4).

By this naive argument, cutting the speed in half reduces
the absolute temperature by about 40%, from ~1690 K to
about 1000 K.

I don't think you can assume density is constant, though,
at least in a lifting reentry.

Paul
Andrew Nowicki
2004-06-20 20:39:13 UTC
Permalink
Post by Paul F. Dietz
By this naive argument, cutting the speed in half reduces
the absolute temperature by about 40%, from ~1690 K to
about 1000 K.
That is still not bad! Melting point temperature of
aluminum is 930K. If the rocket is pump-fed, its long,
flimsy tank will melt away. If however, it is a stubby,
pressure-fed tank of the engine cluster, its thick
bottom will absorb the heat and the fan inside the
tank will carry the heat away to the rest of the tank.
Image of the engine cluster launcher:
Loading Image...
Henry Spencer
2004-06-20 22:28:08 UTC
Permalink
Post by Andrew Nowicki
Post by Paul F. Dietz
the absolute temperature by about 40%, from ~1690 K to
about 1000 K.
That is still not bad! Melting point temperature of
aluminum is 930K.
However, maximum *service* temperature -- the temperature at which
aluminum alloys retain useful amounts of strength -- is rather lower.
Post by Andrew Nowicki
If the rocket is pump-fed, its long, flimsy tank will melt away.
If the designer has goofed and neglected to protect it, that is. (By the
way, you're assuming that said tank is aluminum, which it might not be.)
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert | ***@spsystems.net
Andrew Nowicki
2004-06-21 03:34:58 UTC
Permalink
Andrew Nowicki wrote:
AN> That is still not bad! Melting point temperature
AN> of aluminum is 930K.

Henry Spencer wrote:
HS> However, maximum *service* temperature -- the
HS> temperature at which aluminum alloys retain useful
HS> amounts of strength -- is rather lower.

True.

AN> If the rocket is pump-fed, its long, flimsy
AN> tank will melt away.

HS> If the designer has goofed and neglected to
HS> protect it, that is.

Is there a lightweight insulation that can do
the job? Maybe 3M's Nextel?

HS> (By the way, you're assuming that said tank is
HS> aluminum, which it might not be.)

There are 4 options:
- Aluminum alloys are cheap and have high
thermal conductivity which is useful in engines
and heat sinks. If this is going to be integral
engine/tank pressure-fed design, it would be
nice to use the same material for the engine
and the tank to avoid thermal expansion problems.
- Titanium alloys has high melting point temperature,
but low thermal conductivity -- not good for the
engine.
- Composite tanks have impressive specific strength
(strength-to-weight ratio), but they are hard
to integrate with metal parts because of their
different coefficient of thermal expansion.
- Steel is inferior to the other materials.

AN> Russian Baikal is a winged, reusable first stage which
AN> is going to be a part of a two stage launcher...
AN> Russia is almost a landlocked country, so they have no
AN> choice but to make the winged first stage.

HS> Sure they have. They were planning to recover the
HS> Energia first stage (the strap-ons) with parachutes.

Yes. I have seen a russian drawing of a rocket hanging
on a parachute and being picked up by a helicopter.
I guess they favor the winged Baikal now.

HS> For that matter, Kistler planned to launch from Nevada,
HS> and recover its first stage -- at the launch site,
HS> after a post-staging turnaround burn -- with parachutes
HS> and airbags.

Gas bags were used on Mars, but the Soyuz capsules have
small rockets instead of the airbags. The rockets
malfunctioned a few times, but they were not replaced
by the gas bags. The gas bags may be feasible for a
stubby rocket, but a slender one would need lots of
them. If you launch a two stage rocket from Mojave,
its first stage will land in a rather populated area,
so it will need a landing site and a special parachute
which guides it to the landing site. Cross-range of
such a parachute is not impressive, so the first stage
must be guided before the parachute opens.

All these complications add up to the cost.

AN> A pressure-fed splashdown rocket is much simpler
AN> and cheaper than the Baikal.

HS> Simpler and cheaper to build, yes. But as for
HS> simpler and cheaper to operate... the verdict has
HS> to be "not proven".

'Not proven' is a reasonable argument against a novel
contraption which is either very complex, or fails
catastrophically, or has to work in a very hostile
environment. Long time ago (1968) Arthur Schnitt ran
very successful static tests of pressure-fed 'dumb
boosters.' Pressure-fed rockets made of aluminum
alloy have dry/wet mass ratio of about 0.1. Pump-fed
rockets have the ratio of about 0.06, but they are
not completely dry when they stop running. My favorite
design, the engine cluster, has high expansion ratio,
so its specific impulse is also high: 330 seconds --
not bad for oxygen/methane. Maybe you are just too
sophisticated to appreciate the simple beauty of the
AK-47 rifle and the pressure-fed rockets :-)
Andrew Nowicki
2004-06-19 23:37:39 UTC
Permalink
Post by Alan Anderson
I've always agreed with the idea that dropping machinery
in saltwater and fishing it back out isn't a great thing
to do if you want to use it again without significant
refurbishing.
What is wrong with it? You can keep an unpainted titanium
rocket in the saltwater for many years without any adverse
effects except biofouling (things growing on it). There are
paints which prevent biofouling. Unpainted aluminum rocket
can be kept in the salt water for a few days without any
signs of corrosion. (Many large ships and tankers are made
of painted aluminum. The Coast Guard is replacing its steel
buoys with aluminum buoys.)
Post by Alan Anderson
What's wrong with spending the bit of extra effort required
to simply *land* the things and reuse them?
The pressure-fed rocket has almost no moving part. It can
be made in a shipyard. The rocket-plane is at least one
order of magnitude more expensive. It has lots of moving
parts which can fail. Look at the russian Baikal:
http://www.spacedaily.com/news/rocketscience-03j.html
It has foldable wings, jet engines, landing gear...
Post by Alan Anderson
Appropriate up-front engineering can lower the operational
costs of staging. A lot of cost can be saved if your first
stage rocket comes back to the launch site by itself, and
if it basically just needs to be brushed off and
recharged/refueled before it's ready to have an upper stage
vehicle latched on for the next launch.
If the rocket-planes do not crash upon landing, they may be
feasible. Anyway, the idea of a reusable first stage is more
important than its implementation. The range safety is more
important -- I doubt anyone can get a permit to fly his rocket
launcher over a populated area.
John Carmack
2004-06-23 05:50:53 UTC
Permalink
Post by Andrew Nowicki
Post by Alan Anderson
What's wrong with spending the bit of extra effort required
to simply *land* the things and reuse them?
The pressure-fed rocket has almost no moving part. It can
be made in a shipyard. The rocket-plane is at least one
order of magnitude more expensive. It has lots of moving
http://www.spacedaily.com/news/rocketscience-03j.html
It has foldable wings, jet engines, landing gear...
Look at:

http://media.armadilloaerospace.com/2004_06_15/perfectBoostedHop.mpg

An actual pressure fed rocket with almost no moving parts doing a
powered landing. It is my considered opinion that this is The Right
Way To Do It. Build a big, simple booster that lofts a high
performance upper stage all the way out of the atmosphere, then
returns to land on the same pad it took off from. At first flance it
sounds like an inefficient staging strategy, since the upper stage
requires nearly SSTO dV, but removing the requirment of boosting
through the atmosphere (optimize only for vaccuum boost and reentry)
does still simplify the problem quite a bit, and the operational and
testing aspects are great.

John Carmack
www.armadilloaerospace.com
johnhare
2004-06-23 08:55:12 UTC
Permalink
Post by Earl Colby Pottinger
Post by Andrew Nowicki
Post by Alan Anderson
What's wrong with spending the bit of extra effort required
to simply *land* the things and reuse them?
The pressure-fed rocket has almost no moving part. It can
be made in a shipyard. The rocket-plane is at least one
order of magnitude more expensive. It has lots of moving
http://www.spacedaily.com/news/rocketscience-03j.html
It has foldable wings, jet engines, landing gear...
http://media.armadilloaerospace.com/2004_06_15/perfectBoostedHop.mpg
An actual pressure fed rocket with almost no moving parts doing a
powered landing. It is my considered opinion that this is The Right
Way To Do It. Build a big, simple booster that lofts a high
performance upper stage all the way out of the atmosphere, then
returns to land on the same pad it took off from. At first flance it
sounds like an inefficient staging strategy, since the upper stage
requires nearly SSTO dV, but removing the requirment of boosting
through the atmosphere (optimize only for vaccuum boost and reentry)
does still simplify the problem quite a bit, and the operational and
testing aspects are great.
John Carmack
www.armadilloaerospace.com
I may be in disagreement with you about the nearly SSTO performance
requirement. MR for SSTO seems to be about 16 (Lox/Kero) from the
ground, and 10 from the vacuum altitude you deliver to. Going from
6.25% dry mass including payload to 10% dry mass including payload
is a major gain in margins. Even without the mass savings on lighter
engine and tank mass percentage, 37.5% of the upper stage dry mass
becomes available to increase payload. I was convinced several years
ago by Len Cormiers' Space Van booster concepts.

I think our goals might be similar with a slight difference in methods and
means :-), not to mention real world experience. I hope to start closing the
gap on the last two real soon now, same as I did last year, and the year
before that....
Pete Lynn
2004-06-25 01:53:53 UTC
Permalink
Post by johnhare
I may be in disagreement with you about the nearly SSTO
performance requirement. MR for SSTO seems to be about 16
(Lox/Kero) from the ground, and 10 from the vacuum altitude
you deliver to. Going from 6.25% dry mass including payload to
10% dry mass including payload is a major gain in margins. Even
without the mass savings on lighter engine and tank mass
percentage, 37.5% of the upper stage dry mass becomes
available to increase payload. I was convinced several years
ago by Len Cormiers' Space Van booster concepts.
Me too, assisted SSTO where you stage just above the atmosphere such
that your lower stage can still easily return to the launch site, (this
is critical), seems like such an ideal way of doing things. These are
two very different regimes prompting two very different optimal
solutions. Trying to do it all in one SSTO will just result in a
compromised design, which does not really gain you anything.

If there was such a cheap reusable assist stage commercially available,
then even very small orbital vehicles, (less than 100kg), could be
developed at almost the hobbyist level. There would no longer be an
aerodynamically imposed small scale limit on orbital vehicles.
Development of small orbital vehicles could be directly within the means
of individuals, a very low cost Prize on that basis could be real
interesting.

There are a number of different approaches to the assist stage. I have
come to quite dislike the straight aircraft approach, not to deride
Scaled Composites, (they are getting the results), but I suspect it has
cost them 5-10 times as much as it should. This is telling, they used
to be the pin up boys of low cost development, but were they really? I
fear that they opted for the design that they did not because it was the
right one, but because it was the only one they knew how to make.

One of the things that I am greatly impressed with Armadillo over, in
addition to their proper low cost development approach, is their pure
nothing but rocket mentality. This keeps weights and costs low,
especially during development, optional extras that provide greater
efficiency at greater complexity can come later when the market is ready
to pay for it.

In the long term the straight VTVL rocket assist stage will be very fuel
hungry, gravity losses dominate so this probably favours aerodynamic
augmentation. I do still quite like VTVL, speed is useful and the white
knight takes something like an hour to get to height, and not very high
at that. I suspect that we need to go much higher than subsonic air
breathing engines allows. Although I expect the assist stage might
fully aerodynamically shield the upper stage, supersonic aerodynamic
vehicles tend to cost, I am unsure of this approach.

So we have the pure VTVL rocket and I am guessing you are favoring this
type of VTVL vehicle that instead uses your very high T/W air breathing
engine and perhaps goes supersonic, the more I think about this, the
more I like it, no wings. This might almost reach a 100km, can you do
it? I suppose I still favour what is effectively a very refined rocket
powered paraglider. This is probably still the cheapest to develop and
operate in the short term, but it is a bit slow and limited in height.
I will continue to investigate various more refined hybrid type
solutions that might overcome some of these weaknesses, I am less sure
of this than I used to be, assuming you can do it.
Post by johnhare
I think our goals might be similar with a slight difference in
methods and means :-), not to mention real world experience. I
hope to start closing the gap on the last two real soon now, same
as I did last year, and the year before that....
And me too. :-)

I am making some progress on the tethered wing thing, though initial
commercialization will be elsewhere, (where the money is). I am hoping
that maybe five years from now I will be able to make one for rocket
landing. Hopefully for around 1% landing weight I can build one that
provides a glide rate of around five, if desired, with soft vertical
landing, perhaps without the need for any landing gear. This should be
lighter than any of the alternatives, it could also be easily powered.

Pete.
johnhare
2004-06-25 08:48:15 UTC
Permalink
Post by Pete Lynn
If there was such a cheap reusable assist stage commercially available,
then even very small orbital vehicles, (less than 100kg), could be
developed at almost the hobbyist level. There would no longer be an
aerodynamically imposed small scale limit on orbital vehicles.
Development of small orbital vehicles could be directly within the means
of individuals, a very low cost Prize on that basis could be real
interesting.
There are a number of different approaches to the assist stage. I have
come to quite dislike the straight aircraft approach, not to deride
Scaled Composites, (they are getting the results), but I suspect it has
cost them 5-10 times as much as it should. This is telling, they used
to be the pin up boys of low cost development, but were they really? I
fear that they opted for the design that they did not because it was the
right one, but because it was the only one they knew how to make.
I happen to favor the straight aircraft aproach for regulatory reasons.
Most of the possible launch sites within reasonable commute distance
of my house have valuable property within a few miles. Given the
difficulty of proving that you are not going to cause damage, I prefer
the option of flying 20-50 miles from a runway to a salt water launch
position.
Post by Pete Lynn
One of the things that I am greatly impressed with Armadillo over, in
addition to their proper low cost development approach, is their pure
nothing but rocket mentality. This keeps weights and costs low,
especially during development, optional extras that provide greater
efficiency at greater complexity can come later when the market is ready
to pay for it.
In the long term the straight VTVL rocket assist stage will be very fuel
hungry, gravity losses dominate so this probably favours aerodynamic
augmentation. I do still quite like VTVL, speed is useful and the white
knight takes something like an hour to get to height, and not very high
at that. I suspect that we need to go much higher than subsonic air
breathing engines allows. Although I expect the assist stage might
fully aerodynamically shield the upper stage, supersonic aerodynamic
vehicles tend to cost, I am unsure of this approach.
The pure rocket VTVL outperforms HTHL by a good margin. Air
augmentation is very iffy for VTVL, requiring 30+ to 1 T/W ratios
to compete.
Post by Pete Lynn
So we have the pure VTVL rocket and I am guessing you are favoring this
type of VTVL vehicle that instead uses your very high T/W air breathing
engine and perhaps goes supersonic, the more I think about this, the
more I like it, no wings. This might almost reach a 100km, can you do
it? I suppose I still favour what is effectively a very refined rocket
powered paraglider. This is probably still the cheapest to develop and
operate in the short term, but it is a bit slow and limited in height.
I will continue to investigate various more refined hybrid type
solutions that might overcome some of these weaknesses, I am less sure
of this than I used to be, assuming you can do it.
My projected high T/W air breathing engine is only useful if the group
has pre decided to use wings and wheels. I grit my teeth and try to work
around that but so far I have not been able to get the numbers to close for
anything else. The point of my concept is to eliminate as much parasite
engine mass as possible during the real rocket acceleration.
Joe Strout
2004-06-25 14:21:16 UTC
Permalink
Post by johnhare
Post by Pete Lynn
There are a number of different approaches to the assist stage. I have
come to quite dislike the straight aircraft approach, not to deride
Scaled Composites, (they are getting the results), but I suspect it has
cost them 5-10 times as much as it should. This is telling, they used
to be the pin up boys of low cost development, but were they really? I
fear that they opted for the design that they did not because it was the
right one, but because it was the only one they knew how to make.
I happen to favor the straight aircraft aproach for regulatory reasons.
Most of the possible launch sites within reasonable commute distance
of my house have valuable property within a few miles. Given the
difficulty of proving that you are not going to cause damage, I prefer
the option of flying 20-50 miles from a runway to a salt water launch
position.
Another alternative to consider is to make the first stage a
high-altitude balloon or airship. These can go a little more than 10 km
altitude, which admittedly is a far cry from 100 km, but is still a lot
closer to vacuum than launching from the ground.

Of course this is what the folks at JP Aerospace have been saying for
years.

Best,
- Joe

,------------------------------------------------------------------.
| Joseph J. Strout Check out the Mac Web Directory: |
| ***@strout.net http://www.macwebdir.com |
`------------------------------------------------------------------'
Pete Lynn
2004-06-26 01:20:29 UTC
Permalink
Post by johnhare
My projected high T/W air breathing engine is only useful if the
group has pre decided to use wings and wheels. I grit my teeth
and try to work around that but so far I have not been able to
get the numbers to close for anything else. The point of my
concept is to eliminate as much parasite engine mass as possible
during the real rocket acceleration.
Consider this approach, a VTVL air breathing lower stage, that follows a
rocket trajectory, (up and back), to something like 50-100km,
(supersonic). This should take less than ten minutes and if all you
have to do is load and fuel up you might be able to do this every half
an hour. Turn around time should be quicker than a similar rocket, no
oxidizer, longer life engines, more like a jet. This might require
something like a fifth the fuel of a similar rocket stage? Heating
loads are very brief and tankage minimal, the design is not very
constrained by weight or efficiency so cost should be much lower.

Now assuming sometime in the distant future where flight rates are
maximized and costs reduce to a point where fuel is not cheap. The
above assist stage might launch twice an hour serving say ten near
SSTOs. In this circumstance it is drymass times flight rate that is
critical, not straight drymass, and at such high flight rates even that
is of little importance.

A slow assist stage that takes an hour instead of five minutes to launch
your near SSTO, at maximum flight rate, would require around ten times
as many assist stages and 50% more near SSTO drymass, (the real cost),
to provide the same mass flow rate to LEO. In the long term a winged
launch vehicle is not acceptable, we have to go straight up.

The VTVL air breather assist stage should be as fast as a similar
rocket, and be much cheaper to operate. If the engines cost the same by
weight but weigh ten times as much and last ten times as long, then the
extra drymass will cost the same, though I expect it would be in the
noise anyway.

What kind of cost and T/W could be expected from such a low cost low
efficiency engine, including intakes. Would such a vehicle necessarily
be much harder to develop than a rocket equivalent.

This all assumes long term, maximum flight rate conditions, in the short
term, development cost is almost everything.

Pete.
johnhare
2004-06-26 08:51:43 UTC
Permalink
Post by Pete Lynn
Post by johnhare
My projected high T/W air breathing engine is only useful if the
group has pre decided to use wings and wheels. I grit my teeth
and try to work around that but so far I have not been able to
get the numbers to close for anything else. The point of my
concept is to eliminate as much parasite engine mass as possible
during the real rocket acceleration.
Consider this approach, a VTVL air breathing lower stage, that follows a
rocket trajectory, (up and back), to something like 50-100km,
(supersonic). This should take less than ten minutes and if all you
have to do is load and fuel up you might be able to do this every half
an hour. Turn around time should be quicker than a similar rocket, no
oxidizer, longer life engines, more like a jet. This might require
something like a fifth the fuel of a similar rocket stage? Heating
loads are very brief and tankage minimal, the design is not very
constrained by weight or efficiency so cost should be much lower.
For VTVL, pure rocket will beat my ABE concept unless it considerably
beats my current T/W estimates. I need oxidizer also, just less of it, so
number of procedures is similar for no time gain on the ABE. I see
no reason why a properly set up rocket should be lower life than
a jet engine. Fuel savings are less than double with the balance
being oxidizer. ~70% of the rocket fuel being LOX.
Post by Pete Lynn
Now assuming sometime in the distant future where flight rates are
maximized and costs reduce to a point where fuel is not cheap. The
above assist stage might launch twice an hour serving say ten near
SSTOs. In this circumstance it is drymass times flight rate that is
critical, not straight drymass, and at such high flight rates even that
is of little importance.
A slow assist stage that takes an hour instead of five minutes to launch
your near SSTO, at maximum flight rate, would require around ten times
as many assist stages and 50% more near SSTO drymass, (the real cost),
to provide the same mass flow rate to LEO. In the long term a winged
launch vehicle is not acceptable, we have to go straight up.
Disagree on that hour being critical. I would be thrilled with a launch
assist platform flying ten times a day for revenue.
Post by Pete Lynn
The VTVL air breather assist stage should be as fast as a similar
rocket, and be much cheaper to operate. If the engines cost the same by
weight but weigh ten times as much and last ten times as long, then the
extra drymass will cost the same, though I expect it would be in the
noise anyway.
I'm looking at ABE engines with a quarter the T/W of rockets.
Post by Pete Lynn
What kind of cost and T/W could be expected from such a low cost low
efficiency engine, including intakes. Would such a vehicle necessarily
be much harder to develop than a rocket equivalent.
My numbers suggest that engine cost will be similar to a rocket of similar
thrust. Intakes should be minimal with no supersonic airbreathing
capability.
Harder to develope with two engine systems instead of one.
Post by Pete Lynn
This all assumes long term, maximum flight rate conditions, in the short
term, development cost is almost everything.
Agree on development cost. Just because I have a concept I'm excited
about does not mean I believe it is the answer to all problems. The current
estimate is that the main use is on HTHL for the purpose of minimizing
parasite dry mass during real boost.

Secondary use is very iffy. If the concept
can be made to run on gaseous oxygen and fuel, then a very small engine
might be used for OMS sucking the tank pressurant gasses down to one psi
or so. Unused propellants would boil and become available for thrust.
This use would be compressor fed pure rocket mode. Its' use
would depend on just how much unused propellants can be scavanged
vs engine dry mass.
Post by Pete Lynn
Pete.
Pete Lynn
2004-06-27 03:15:02 UTC
Permalink
Post by johnhare
For VTVL, pure rocket will beat my ABE concept unless it
considerably beats my current T/W estimates. I need oxidizer
also, just less of it, so number of procedures is similar for no time
gain on the ABE. I see no reason why a properly set up rocket
should be lower life than a jet engine. Fuel savings are less than
double with the balance being oxidizer. ~70% of the rocket fuel
being LOX.
Yes, I checked some numbers, which I should have done in the first
place...
Post by johnhare
Disagree on that hour being critical. I would be thrilled with a
launch assist platform flying ten times a day for revenue.
Yes, I was considering distant future where orbital transports compete
with round the world air travel, and turn around times similarly matter
with vehicle designs competing on that basis. I have often wondered if
this might be a bigger, easier and more dependable initial market that
space tourism. Obviously short term flight rates are otherwise, though
I suspect there might be some correlation between inherent high flight
rate design and low cost development. Such development might be quicker
and easier.
Post by johnhare
I'm looking at ABE engines with a quarter the T/W of rockets.
My numbers suggest that engine cost will be similar to a rocket
of similar thrust. Intakes should be minimal with no supersonic
airbreathing capability. Harder to develope with two engine
systems instead of one.
Supersonic air breathing really does kill efficiency and T/W. I am
beginning to think launch vehicles should generally avoid it.
Post by johnhare
Agree on development cost. Just because I have a concept I'm
excited about does not mean I believe it is the answer to all
problems. The current estimate is that the main use is on HTHL
for the purpose of minimizing parasite dry mass during real
boost.
I am thinking that it should be very applicable to subsonic airlaunch
systems, which still seem to add up to me. Subsonic air launch tends to
come down to one thing, propulsion, high thrust at altitude.
Post by johnhare
Secondary use is very iffy. If the concept can be made to run on
gaseous oxygen and fuel, then a very small engine might be used
for OMS sucking the tank pressurant gasses down to one psi
or so. Unused propellants would boil and become available for
thrust. This use would be compressor fed pure rocket mode. Its'
use would depend on just how much unused propellants can be
scavanged vs engine dry mass.
Should work, though as you say, viability will depend on the
availability of unused propellant.

What of turbo pump designs?

Pete.
johnhare
2004-06-27 09:02:30 UTC
Permalink
Post by Pete Lynn
Post by johnhare
Secondary use is very iffy. If the concept can be made to run on
gaseous oxygen and fuel, then a very small engine might be used
for OMS sucking the tank pressurant gasses down to one psi
or so. Unused propellants would boil and become available for
thrust. This use would be compressor fed pure rocket mode. Its'
use would depend on just how much unused propellants can be
scavanged vs engine dry mass.
Should work, though as you say, viability will depend on the
availability of unused propellant.
What of turbo pump designs?
I have several concepts on paper. If I ever get permiting for my shop,
I will be able to start investigating them. IMO, pressure fed is the wrong
road for large rockets. I need operating hardware at least to proof of
concept level before trying to convince others. What if I convince them,
and then turn out to be wrong? IMO, some people create a lot
of extra work for themselves when they decide in advance not to
consider pumps.


Turbopumps considerably reduce parasite mass compared to pressure fed
while improving performance. The trick is to build them for the application
without greatly increasing parts count and failure modes. I believe it is
possible to do a pump fed engine with a T/W of 200 including all
attachments.
Tank mass can then be lighter, simpler, cheaper, or some reasonable
combination for better vehicle economics.
Post by Pete Lynn
Pete.
Pete Lynn
2004-06-28 01:07:35 UTC
Permalink
Post by johnhare
Post by Pete Lynn
What of turbo pump designs?
I have several concepts on paper. If I ever get permiting for my
shop, I will be able to start investigating them. IMO, pressure fed
is the wrong road for large rockets. I need operating hardware at
least to proof of concept level before trying to convince others.
What if I convince them, and then turn out to be wrong? IMO,
some people create a lot of extra work for themselves when they
decide in advance not to consider pumps.
Turbo pumps do seem to start looking ever more attractive with increased
scale, a pump design that scaled down better, which your design should,
would help. I was wondering if a water pump variant might be somewhat
easer to develop, yet still demonstrate the general viability, (with a
little dimensional analysis). This might initially ease development.
Post by johnhare
Turbopumps considerably reduce parasite mass compared to
pressure fed while improving performance. The trick is to build
them for the application without greatly increasing parts count
and failure modes. I believe it is possible to do a pump fed
engine with a T/W of 200 including all attachments. Tank mass
can then be lighter, simpler, cheaper, or some reasonable
combination for better vehicle economics.
That estimate sounds about right to me, an order of magnitude turbo pump
weight reduction might be possible. This is sort of an axial flow pump
regime, so I have been wondering if a super cavitating approach might be
better. Although this seriously hurts efficiency, this may not matter.
It might enable a single stage pump at very high shaft speed which might
be much lighter, simpler and cheaper. This might also enable much lower
tank and inlet pressure. For staged combustion, the turbine duty cycle
approach that incorporates the pre burner directly seems applicable.

Pete.
johnhare
2004-06-28 08:43:07 UTC
Permalink
Post by Pete Lynn
Post by johnhare
Post by Pete Lynn
What of turbo pump designs?
I have several concepts on paper. If I ever get permiting for my
shop, I will be able to start investigating them. IMO, pressure fed
is the wrong road for large rockets. I need operating hardware at
least to proof of concept level before trying to convince others.
What if I convince them, and then turn out to be wrong? IMO,
some people create a lot of extra work for themselves when they
decide in advance not to consider pumps.
Turbo pumps do seem to start looking ever more attractive with increased
scale, a pump design that scaled down better, which your design should,
would help. I was wondering if a water pump variant might be somewhat
easer to develop, yet still demonstrate the general viability, (with a
little dimensional analysis). This might initially ease development.
There are several possible methods for producing modest capability
pumping systems. I see it as one of a dozen or so major systems. This
particular system makes some of the others easier to do. Apparently
I am more comfortable with the idea of dynamic systems aboard than
some of the more experienced builders. I just see a low level pump system
as being easier than say the electrical system of a ship.
Post by Pete Lynn
Post by johnhare
Turbopumps considerably reduce parasite mass compared to
pressure fed while improving performance. The trick is to build
them for the application without greatly increasing parts count
and failure modes. I believe it is possible to do a pump fed
engine with a T/W of 200 including all attachments. Tank mass
can then be lighter, simpler, cheaper, or some reasonable
combination for better vehicle economics.
That estimate sounds about right to me, an order of magnitude turbo pump
weight reduction might be possible. This is sort of an axial flow pump
regime, so I have been wondering if a super cavitating approach might be
better. Although this seriously hurts efficiency, this may not matter.
It might enable a single stage pump at very high shaft speed which might
be much lighter, simpler and cheaper. This might also enable much lower
tank and inlet pressure. For staged combustion, the turbine duty cycle
approach that incorporates the pre burner directly seems applicable.
I am talking on two levels here. Simple pumps on the cheap for suborbital
vehicles, and new high performance concepts for eventual orbital use. The
technical details of my ideas are not proven, and discussing them here would
create far more smoke than fire. They are not derived from the cagejet
ABE. Enough difference to take several pages to describe. I believe I have
reached the point that people capable of constructive technical advice
won't post it on usenet.
Post by Pete Lynn
Pete.
Andrew Nowicki
2004-06-26 17:39:32 UTC
Permalink
Post by Pete Lynn
Consider this approach, a VTVL air breathing lower stage, that follows a
rocket trajectory, (up and back), to something like 50-100km,
(supersonic).
You can't fly air breathing engine above the altitude
of 30 kilometers because very thin air mixed with
jet fuel vapor cannot be ignited. To make it burn you
would have to compress it first, but compression would
generate high temperature which would melt the engine.

THE MAIN PROBLEM IS REUSABILITY OF THE ROCKET LAUNCHERS,
WHICH IS ALMOST THE SAME AS SURVIVING HIGH TEMPERATURE
AND HIGH MECHANICAL STRESS OF ATMOSPHERIC REENTRY.
Post by Pete Lynn
What kind of cost and T/W could be expected from such a low cost low
efficiency engine, including intakes. Would such a vehicle necessarily
be much harder to develop than a rocket equivalent.
Thrust-to-weight ratio of jet engines is about
one. If you add the weight of rocket fuel, you
cannot fly your craft straight up. Pegasus is
a small rocket launcher which is lifted by a
plane to the stratosphere. Most people believe
that the little assist that jet engines provide
is not worth the trouble.
Pete Lynn
2004-06-27 01:35:16 UTC
Permalink
Post by Andrew Nowicki
Post by Pete Lynn
Consider this approach, a VTVL air breathing lower stage,
that follows a rocket trajectory, (up and back), to something
like 50-100km, (supersonic).
You can't fly air breathing engine above the altitude
of 30 kilometers because very thin air mixed with
jet fuel vapor cannot be ignited. To make it burn you
would have to compress it first, but compression would
generate high temperature which would melt the engine.
I think the record for a MIG 25 was something like 36.5 km, on a
ballistic trajectory. The SR-71 was I think good for around mach 3 at
25 km. Thus a pure VTVL design with only five minutes worth of fuel
might achieve the overall thrust to weight ratio to reach that speed and
altitude while going near vertical. If so that might be good for near
80 km.

With water injection a much cheaper rocket would seem to have similar
performance and fuel, (excluding oxidizer), consumption. Depending on
ultimate H2O2 cost, I suspect this could be similar.
So I now favour this over supersonic air breathing approaches.

Subsonic launch using aerodynamic lift can have much lower fuel
consumption and cost than a rocket within its far more limited speed and
altitude range, maybe 20-30 km with advanced propulsion. This provides
far less useful delta v and the near SSTO has to work much harder, so
this might be less efficient overall. There is a definite advantage in
having a pure lower stage that maximizes delta v while still being able
to efficiently return to the original launch site.

A possibility that suggests itself is a subsonic airlaunch climbing up
range, followed by a pure rocket lower stage that can now go much higher
and faster while still returning to the original launch site, followed
by an upper stage to LEO. This is an air launched TSTO system with air
launched SSTO type convenience and turn around, it mostly gives you the
benefits of both worlds.

Note, White knight is not a low cost or high lift air launch system.

Pete.
Earl Colby Pottinger
2004-06-25 17:30:29 UTC
Permalink
Post by Pete Lynn
Post by johnhare
I may be in disagreement with you about the nearly SSTO
performance requirement. MR for SSTO seems to be about 16
(Lox/Kero) from the ground, and 10 from the vacuum altitude
you deliver to. Going from 6.25% dry mass including payload to
10% dry mass including payload is a major gain in margins. Even
without the mass savings on lighter engine and tank mass
percentage, 37.5% of the upper stage dry mass becomes
available to increase payload. I was convinced several years
ago by Len Cormiers' Space Van booster concepts.
Me too, assisted SSTO where you stage just above the atmosphere such
that your lower stage can still easily return to the launch site, (this
is critical), seems like such an ideal way of doing things. These are
two very different regimes prompting two very different optimal
solutions. Trying to do it all in one SSTO will just result in a
compromised design, which does not really gain you anything.
However, Henry Spencer has a good point when he said that first you should
try to make a SSTO first. The closer you get to SSTO the better for the
payload of a boosted design. Beside, trying for a SSTO forces you to look a
designs and ideas that you might skip over if you start designing a TSTO in
the first place.
Post by Pete Lynn
If there was such a cheap reusable assist stage commercially available,
then even very small orbital vehicles, (less than 100kg), could be
developed at almost the hobbyist level. There would no longer be an
aerodynamically imposed small scale limit on orbital vehicles.
Development of small orbital vehicles could be directly within the means
of individuals, a very low cost Prize on that basis could be real
interesting.
At that point I really expect the paper work to cost more and weigh more that
the orbital craft :)
Post by Pete Lynn
There are a number of different approaches to the assist stage. I have
come to quite dislike the straight aircraft approach, not to deride
Scaled Composites, (they are getting the results), but I suspect it has
cost them 5-10 times as much as it should. This is telling, they used
to be the pin up boys of low cost development, but were they really? I
fear that they opted for the design that they did not because it was the
right one, but because it was the only one they knew how to make.
In thier defense, it is usually best to do what you know best, and second
they probably designed, builted, and debugged White Knight for less money
than NASA would have paid to rent, modify, demodify a commercial plane.
Compared to where we want to go they were not low cost, compared to where we
are coming from in the past. They were very low cost.
Post by Pete Lynn
One of the things that I am greatly impressed with Armadillo over, in
addition to their proper low cost development approach, is their pure
nothing but rocket mentality. This keeps weights and costs low,
especially during development, optional extras that provide greater
efficiency at greater complexity can come later when the market is ready
to pay for it.
Agreed. Not just weighs and costs. The software modelling was simpler,
modifing the design was also easier IE the switch from four rockets to one.
Plus the need of only a pad of concrete/packed soil mean testing can be moved
very easyily.
Post by Pete Lynn
In the long term the straight VTVL rocket assist stage will be very fuel
hungry, gravity losses dominate so this probably favours aerodynamic
augmentation. I do still quite like VTVL, speed is useful and the white
knight takes something like an hour to get to height, and not very high
at that. I suspect that we need to go much higher than subsonic air
breathing engines allows. Although I expect the assist stage might
fully aerodynamically shield the upper stage, supersonic aerodynamic
vehicles tend to cost, I am unsure of this approach.
I don't agree unless you are only talking about a craft to lift hobbist
designs, if only them then yes I agree.
Post by Pete Lynn
So we have the pure VTVL rocket and I am guessing you are favoring this
type of VTVL vehicle that instead uses your very high T/W air breathing
engine
In real life there are no very high T/W air breathing engines
Post by Pete Lynn
and perhaps goes supersonic, the more I think about this, the
more I like it, no wings. This might almost reach a 100km, can you do
it? I suppose I still favour what is effectively a very refined rocket
powered paraglider. This is probably still the cheapest to develop and
operate in the short term, but it is a bit slow and limited in height.
I will continue to investigate various more refined hybrid type
solutions that might overcome some of these weaknesses, I am less sure
of this than I used to be, assuming you can do it.
A pure rocket design is always simpler. May not be cheaper, but it is
simpler and thus less likely to have a bad design error hidden away somewhere.
Post by Pete Lynn
Post by johnhare
I think our goals might be similar with a slight difference in
methods and means :-), not to mention real world experience. I
hope to start closing the gap on the last two real soon now, same
as I did last year, and the year before that....
And me too. :-)
The more ways tried the better. NO-ONE but no-one really knows what the bet
methods are yet.
Post by Pete Lynn
I am making some progress on the tethered wing thing, though initial
commercialization will be elsewhere, (where the money is). I am hoping
that maybe five years from now I will be able to make one for rocket
landing. Hopefully for around 1% landing weight I can build one that
provides a glide rate of around five, if desired, with soft vertical
landing, perhaps without the need for any landing gear. This should be
lighter than any of the alternatives, it could also be easily powered.
Pete.
Good Luck. URL?

Earl Colby Pottinger
--
I make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos,
SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to
the time? http://webhome.idirect.com/~earlcp
johnhare
2004-06-26 01:36:30 UTC
Permalink
Post by Earl Colby Pottinger
In real life there are no very high T/W air breathing engines
There might be some coming up. The concept I am looking into
should hit 25/1 fairly easily with Isp ~1,000 or so. Turbine and
rocket based combined cycle. With real engineers using CFD
and proper combustion codes and professionally designed
structure, considerably more.

Not real life yet. Useless for supersonic even if successful.
Possibly useful for winged boosters for crossrange and some
altitude.
Pete Lynn
2004-06-26 01:51:23 UTC
Permalink
Post by Earl Colby Pottinger
Post by Pete Lynn
I am making some progress on the tethered wing thing, though
initial commercialization will be elsewhere, (where the money
is). I am hoping that maybe five years from now I will be able
to make one for rocket landing. Hopefully for around 1%
landing weight I can build one that provides a glide rate of
around five, if desired, with soft vertical landing, perhaps
without the need for any landing gear. This should be
lighter than any of the alternatives, it could also be easily powered.
Pete.
Good Luck. URL?
Not yet, nor can I talk about specifics. But basically you throw away
everything but the Roton rotor tip and fly it similarly as a kite with
lines back to the hub. This cuts your weight to about a tenth for the
same overall performance. The scary problem will be deployment through
the vehicle wake, this will be a long term project.

I pretty much agreed with everything you said so felt no need to comment
further.

Pete.
Andrew Nowicki
2004-06-23 17:04:28 UTC
Permalink
John Carmack wrote:
JC> Look at:
JC> http://media.armadilloaerospace.com/2004_06_15/perfectBoostedHop.mpg

JC> An actual pressure fed rocket with almost no moving parts doing a
JC> powered landing. It is my considered opinion that this is The Right
JC> Way To Do It. Build a big, simple booster that lofts a high
JC> performance upper stage all the way out of the atmosphere, then
JC> returns to land on the same pad it took off from. At first flance it
JC> sounds like an inefficient staging strategy, since the upper stage
JC> requires nearly SSTO dV, but removing the requirment of boosting
JC> through the atmosphere (optimize only for vaccuum boost and reentry)
JC> does still simplify the problem quite a bit, and the operational and
JC> testing aspects are great.

A winged rocket does not need as strong propellant tank as
the splashdown rocket, but it costs more to fabricate and
it may crash during landing.

I am glad you understand some advantages of the pressure-fed
rockets, but I do not understand why you insist on the two stage
design. I do not know what is the specific impulse of your
hydrogen peroxide pressure-fed rocket, but I doubt it is greater
than 150 seconds. It would be a perfect first stage because it
is very safe and reusable. The best design for the second stage
is my engine cluster. So far it exists only on paper, but it
looks very good: mass ratio in the range of 4 to 8 and specific
impulse in the range of 300 to 330 seconds. It is not just
another dumb booster, but a novel, reusable, and inexpensive
design. It is not protected by any patents, so anyone can use
it without any restrictions. Its description is posted at:
http://www.islandone.org/LEOBiblio/SPBI101.HTM#engine_cluster

_________________________________________________________________________

johnhare wrote:
j> I may be in disagreement with you about the nearly SSTO performance
j> requirement. MR for SSTO seems to be about 16 (Lox/Kero) from the
j> ground, and 10 from the vacuum altitude you deliver to. Going from
j> 6.25% dry mass including payload to 10% dry mass including payload
j> is a major gain in margins. Even without the mass savings on lighter
j> engine and tank mass percentage, 37.5% of the upper stage dry mass
j> becomes available to increase payload. I was convinced several years
j> ago by Len Cormiers' Space Van booster concepts.

SSTO development costs billions of dollars. Pressure-fed
rockets are cheaper by orders of magnitude and they are
reusable, reliable, and strong enough to survive reentry
and splashdown.
Earl Colby Pottinger
2004-06-23 20:53:33 UTC
Permalink
Post by Andrew Nowicki
JC> http://media.armadilloaerospace.com/2004_06_15/perfectBoostedHop.mpg
JC> An actual pressure fed rocket with almost no moving parts doing a
JC> powered landing. It is my considered opinion that this is The Right
JC> Way To Do It. Build a big, simple booster that lofts a high
JC> performance upper stage all the way out of the atmosphere, then
JC> returns to land on the same pad it took off from. At first flance it
JC> sounds like an inefficient staging strategy, since the upper stage
JC> requires nearly SSTO dV, but removing the requirment of boosting
JC> through the atmosphere (optimize only for vaccuum boost and reentry)
JC> does still simplify the problem quite a bit, and the operational and
JC> testing aspects are great.
A winged rocket does not need as strong propellant tank as
the splashdown rocket, but it costs more to fabricate and
it may crash during landing.
But you are the only one demanding a splashdown. The rest of us see landing
the booster right back at it launching point as a good thing. Cuts
turn-around time, prevents salt water damage, prevents thermal shock. So why
insist on a water landing where you need the tow the craft back, clean it up,
and check for damages that would never happen by landing back at it's start
point.
Post by Andrew Nowicki
I am glad you understand some advantages of the pressure-fed
rockets, but I do not understand why you insist on the two stage
design.
Maybe because unlike you he is building real rockets and flying them. That
means he is risking his money and life on the designs. He has decided on a
design that will works over a guess.
Post by Andrew Nowicki
I do not know what is the specific impulse of your
hydrogen peroxide pressure-fed rocket, but I doubt it is greater
than 150 seconds.
Right, as usual you are guessing instead of learning. Please real *ALL* of
John's site before mouthing off on how he should build his designs, or for a
quick rundown check out my website before making guesses about other people's
designs.
Post by Andrew Nowicki
It would be a perfect first stage because it
is very safe and reusable. The best design for the second stage
is my engine cluster. So far it exists only on paper, but it
looks very good: mass ratio in the range of 4 to 8 and specific
impulse in the range of 300 to 330 seconds. It is not just
another dumb booster, but a novel, reusable, and inexpensive
design. It is not protected by any patents, so anyone can use
http://www.islandone.org/LEOBiblio/SPBI101.HTM#engine_cluster
Do I see ego :) Have you built a prototype yet, even a simple model to test
your ideas? No! But you want to tell JC a person making his own working
engines what he should use! Please grow up

By the way I just checked out the page you listed. That was not a design,
that is a simple drawing, where are the control valves and thier support
equipment? What starts the engines, or where are catalyst packs? What is
the sizing of the flow lines? What type of injectors are being used? The
list goes on and on.
Post by Andrew Nowicki
_________________________________________________________________________
j> I may be in disagreement with you about the nearly SSTO performance
j> requirement. MR for SSTO seems to be about 16 (Lox/Kero) from the
j> ground, and 10 from the vacuum altitude you deliver to. Going from
j> 6.25% dry mass including payload to 10% dry mass including payload
j> is a major gain in margins. Even without the mass savings on lighter
j> engine and tank mass percentage, 37.5% of the upper stage dry mass
j> becomes available to increase payload. I was convinced several years
j> ago by Len Cormiers' Space Van booster concepts.
SSTO development costs billions of dollars. Pressure-fed
rockets are cheaper by orders of magnitude and they are
reusable, reliable, and strong enough to survive reentry
and splashdown.
There you go with your splashdown again, no-one else wants to do it if they
can afford not, so why keep insisting on it.
Earl Colby Pottinger
--
I make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos,
SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to
the time? http://webhome.idirect.com/~earlcp
Andrew Nowicki
2004-06-23 23:23:11 UTC
Permalink
Andrew Nowicki wrote:
AN> A winged rocket does not need as strong propellant tank as
AN> the splashdown rocket, but it costs more to fabricate and
AN> it may crash during landing.

Earl Colby Pottinger wrote:
ECB> But you are the only one demanding a splashdown.
ECB> The rest of us see landing the booster right back
ECB> at it launching point as a good thing. Cuts
ECB> turn-around time, prevents salt water damage,
ECB> prevents thermal shock.

The winged, reusable rockets make sense if you have to
launch them from a landlocked country or if your rocket
is too flimsy to survive splashdown. Fixed wings produce
atmospheric drag during launch, so foldable wings, Baikal
style are better. Another reason for the foldable wings
is that they can be much bigger than fixed wings, which
of course means higher lift-to-drag ratio, larger
crossrange, and ability to land at the launch site.
The rocket with large wings or jet engines can return
to the launch site within hours instead of days. If
you launch your spacecraft every day, it does make
big difference. Of course, it is possible to haul the
floating rocket with a helicopter, but ships are much
cheaper than helicopters. Russians proposed to catch
descending rocket in midair by the helicopter.

Titanium and aluminum are not damaged by saltwater.
There is no thermal shock during splashdown because
the rocket descends on a parachute before the
splashdown. It maybe warm, but not hot. The solid
rocket boosters of the Space Shuttle are reused after
splashdown.

We are spending too much time talking about rocket wings.
They do not matter much. The engine cluster concept is
infinitely more important because it looks perfect --
low cost, good performance, and virtually indestructible
engine. Description of the engine cluster is posted at:
http://www.islandone.org/LEOBiblio/SPBI101.HTM#engine_cluster
Earl Colby Pottinger
2004-06-24 05:59:48 UTC
Permalink
Post by Andrew Nowicki
AN> A winged rocket does not need as strong propellant tank as
AN> the splashdown rocket, but it costs more to fabricate and
AN> it may crash during landing.
ECB> But you are the only one demanding a splashdown.
ECB> The rest of us see landing the booster right back
ECB> at it launching point as a good thing. Cuts
ECB> turn-around time, prevents salt water damage,
ECB> prevents thermal shock.
The winged, reusable rockets make sense if you have to
launch them from a landlocked country or if your rocket
is too flimsy to survive splashdown. Fixed wings produce
atmospheric drag during launch, so foldable wings, Baikal
style are better. Another reason for the foldable wings
is that they can be much bigger than fixed wings, which
of course means higher lift-to-drag ratio, larger
crossrange, and ability to land at the launch site.
The rocket with large wings or jet engines can return
to the launch site within hours instead of days. If
you launch your spacecraft every day, it does make
big difference. Of course, it is possible to haul the
floating rocket with a helicopter, but ships are much
cheaper than helicopters. Russians proposed to catch
descending rocket in midair by the helicopter.
All this extra hardware and the additional failure modes to avoid burning
fuel, the cheapest part of any rocket. Please try building prototype of your
suggestions, you will quickly learn why part count is more important than
part size.
Post by Andrew Nowicki
Titanium and aluminum are not damaged by saltwater.
Titanium at present does not equal cheap design. Go ask any machine shop.

Oh dear, please don't talk to a marine person if you think salt water does
not affect aluminum, you could kill him from how hard he would laugh.
Post by Andrew Nowicki
There is no thermal shock during splashdown because
the rocket descends on a parachute before the
splashdown. It maybe warm, but not hot. The solid
rocket boosters of the Space Shuttle are reused after
splashdown.
And at a cost greater than just making new ones from start. That is a very
bad example of rocket re-use. Infact at the present way of operation
anything about the shuttle is a bad example of rocket re-use.
Post by Andrew Nowicki
We are spending too much time talking about rocket wings.
They do not matter much.
Then why do you keep harping on slashdown instead of just landing back at the
start point.
Post by Andrew Nowicki
The engine cluster concept is
infinitely more important because it looks perfect --
low cost, good performance, and virtually indestructible
http://www.islandone.org/LEOBiblio/SPBI101.HTM#engine_cluster
And I will repeat what I said about that too: That was not a design, that is
a simple drawing, where are the control valves and thier support equipment?
What starts the engines, or where are catalyst packs? What is the sizing of
the flow lines? What type of injectors are being used? The list goes on and
on.

Until you build a working model don't expect people to jump over to your
designs.

Earl Colby Pottinger
--
I make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos,
SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to
the time? http://webhome.idirect.com/~earlcp
George William Herbert
2004-06-26 19:28:54 UTC
Permalink
Post by Earl Colby Pottinger
Post by Andrew Nowicki
Titanium and aluminum are not damaged by saltwater.
[...]
Oh dear, please don't talk to a marine person if you think salt water does
not affect aluminum, you could kill him from how hard he would laugh.
Plenty of saltwater boats made out of Aluminum.

The problem is... the Al alloys that do OK in salt water
are not the Al alloys that have typical aerospace grade
strength properties. 5052, 5086, 6061, 6063 all do fine
in salt water. 2 and 7 series don't.

What you really want is an alloy which combines high strength,
weldability and as-welded or post-treated strength,
and salt water tolerance. 6061 has strength and salt water
tolerance but loses a lot of strength in welding.
5086 isn't good enough at its basic strength.
7075 isn't seawater tolerant, as are the 2 series.

6013 *might* be ok. I haven't bothered to look up
all the details and see how it does in seawater.


-george william herbert
***@retro.com
Earl Colby Pottinger
2004-06-26 23:10:04 UTC
Permalink
Post by George William Herbert
Post by Earl Colby Pottinger
Post by Andrew Nowicki
Titanium and aluminum are not damaged by saltwater.
[...]
Oh dear, please don't talk to a marine person if you think salt water does
not affect aluminum, you could kill him from how hard he would laugh.
Plenty of saltwater boats made out of Aluminum.
The problem is... the Al alloys that do OK in salt water
are not the Al alloys that have typical aerospace grade
strength properties. 5052, 5086, 6061, 6063 all do fine
in salt water. 2 and 7 series don't.
What you really want is an alloy which combines high strength,
weldability and as-welded or post-treated strength,
and salt water tolerance. 6061 has strength and salt water
tolerance but loses a lot of strength in welding.
5086 isn't good enough at its basic strength.
7075 isn't seawater tolerant, as are the 2 series.
6013 *might* be ok. I haven't bothered to look up
all the details and see how it does in seawater.
Thanks for the details. My point was not to assume you can land in saltwater
just because you used alumium in the construction. I am sure the original
poster was not thinking about alloys needed.

Earl Colby Pottinger
--
I make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos,
SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to
the time? http://webhome.idirect.com/~earlcp
Andrew Nowicki
2004-06-26 23:53:17 UTC
Permalink
Post by George William Herbert
Plenty of saltwater boats made out of Aluminum.
The problem is... the Al alloys that do OK in salt water
are not the Al alloys that have typical aerospace grade
strength properties. 5052, 5086, 6061, 6063 all do fine
in salt water. 2 and 7 series don't.
I have already mentioned aluminum ships and buoys
in this thread. There is big difference between a
boat which has to survive in the saltwater environment
for years, and a rocket stage which floats in the ocean
only a few hours at a time. Commercial boats are usually
made of aluminum alloys coated with pure aluminum,
because pure aluminum is more resistant to saltwater
than aluminum alloys. Alloys coated with pure
aluminum are called Al-clad. Boats are sometimes
coated with anodize coating or paint, but these
coatings are too frail for the space environment.
John Carmack
2004-06-24 04:37:21 UTC
Permalink
Post by Andrew Nowicki
A winged rocket does not need as strong propellant tank as
the splashdown rocket, but it costs more to fabricate and
it may crash during landing.
Why do you keep bringing up wings? Most of the people on this thread
are partial to VTVL.

A BDB can do a powered landing with little more than software changes
and the addition of landing struts (you could even avoid that if you
are REALLY confident in your terminal positioning and land on a
special ground structure, but I don't reccomend that). Yes, you need
to cart some more propellant around, but these are big, easy to
fabricate vehicles that can be "made in shipyards", right? Adding
some size doesn't cost much, and the operational win would be dramatic
compared to a splashdown recovery.

You can't design a high aspect ratio vehicle, but again, it doesn't
really matter for a booster stage. Make it squat, and let the upper
stage be a sphere if it wants to. Go ahead and be highly non-optimal
in the aerodynamics and staging fraction if it gets you good
operability. A booster like this would be a cargo elevator to 100km
or so. Up and down on the hour if you wanted to.
Post by Andrew Nowicki
I am glad you understand some advantages of the pressure-fed
rockets, but I do not understand why you insist on the two stage
design. I do not know what is the specific impulse of your
hydrogen peroxide pressure-fed rocket, but I doubt it is greater
than 150 seconds. It would be a perfect first stage because it
is very safe and reusable. The best design for the second stage
is my engine cluster. So far it exists only on paper, but it
looks very good: mass ratio in the range of 4 to 8 and specific
impulse in the range of 300 to 330 seconds. It is not just
another dumb booster, but a novel, reusable, and inexpensive
design. It is not protected by any patents, so anyone can use
http://www.islandone.org/LEOBiblio/SPBI101.HTM#engine_cluster
Qantity and replication are easy in a spreadsheet or CAD program. It
is a little more troublesome in the real world. We recently made out
lives much, much better by moving from four differentially throttled
engines to a single larger engine with jet vanes. At some point mass
production effects can kick in, but it isn't in the development stage.

Most of the fundamental complexity of a rocket stage is independent of
stage performance. Lots more stages will give lots more problems.
Pushing performance requirements to the edge can easily give even more
problems, which is why I'm not an advocate of a completely SSTO
design, but two stages is going to be both more reliable and easier to
develop and test than more stages.

An upper stage from us would probably use 98% peroxide and kerosene.
Probably still pressure fed, but at a tank pressure of only 100 psi or
less, which doesn't hurt it much in vacuum operation. Make the main
tank a spherical or isotensoid filament wound structure so it has a
very low ballistic coefficient for reentry and a very high mass
fraction. You get a small payload, but if you can land the vehicle
and fly it again without major refurbishment, the economics will win
big.

A gas-and-go RLV would be a huge advance even if it used TEN TIMES the
propellant that a conventional rocket used for a given amount of
propellant.
Post by Andrew Nowicki
SSTO development costs billions of dollars. Pressure-fed
rockets are cheaper by orders of magnitude and they are
reusable, reliable, and strong enough to survive reentry
and splashdown.
The major point of contention is splashdown versus a powered landing.
We have done some work with big parachutes, and I'm not a fan. Taking
a boat out to fish your rocket out of the ocean is going to suck.
Landing the booster is feasible, economical, and gives the best
operational characteristics, as long as you are willing to accept some
limitations on stage trajectory and aspect ratio. I contend that
these are worthwhile tradeoffs.

John Carmack
www.armadilloaerospace.com
Earl Colby Pottinger
2004-06-24 05:59:46 UTC
Permalink
Post by John Carmack
Qantity and replication are easy in a spreadsheet or CAD program. It
is a little more troublesome in the real world. We recently made out
lives much, much better by moving from four differentially throttled
engines to a single larger engine with jet vanes. At some point mass
production effects can kick in, but it isn't in the development stage.
Just minutes ago I made what I think is a break-thru in making a simpler,
cheaper rocket engine. So why did I not do this five years ago when I first
started this? Because it has taken me those five years making drawings,
trying to build designs, having them fail or turn out unbuildable with my
skills or just too expensive to build to reach this point.

Too many people have no idea how hard it is to take a great idea and turn it
into working hardware. And sometimes like in your example above and the time
you did some 'ROTON' type designs you need to go down the wrong path to learn
enough before you can go down the right one.

Earl Colby Pottinger

PS. I hope Burt gets delayed (no one hurt please) I would really like to see
you win the X-Prize.

PSS. Tomorrow I will try out my idea. However I will not be surprize if I
turn out to be wrong and the idea is stupid one. Assuming you know tha
answer before building the hardware is the dumbest thing you can do.
--
I make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos,
SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to
the time? http://webhome.idirect.com/~earlcp
Andrew Nowicki
2004-06-24 17:10:50 UTC
Permalink
John Carmack wrote:

JC> Why do you keep bringing up wings? Most of the people on this thread
JC> are partial to VTVL.

JC> A BDB can do a powered landing with little more than software changes
JC> and the addition of landing struts (you could even avoid that if you
JC> are REALLY confident in your terminal positioning and land on a
JC> special ground structure, but I don't reccomend that). Yes, you need
JC> to cart some more propellant around, but these are big, easy to
JC> fabricate vehicles that can be "made in shipyards", right? Adding
JC> some size doesn't cost much, and the operational win would be dramatic
JC> compared to a splashdown recovery.

Yes, VTVL (vertical takeoff and vertical landing on dry land without
parachute and without wings) is the cheapest option and probably the
best one if the rocket is sturdy enough to survive hard landing
without catastrophic damage. (Russian landing retrorockets malfunctioned
several times.)

JC> The major point of contention is splashdown versus a powered landing.

This issue got more coverage in this thread than it deserves.
Reusability is much more important.

JC> We have done some work with big parachutes, and I'm not a fan. Taking
JC> a boat out to fish your rocket out of the ocean is going to suck.
JC> Landing the booster is feasible, economical, and gives the best
JC> operational characteristics, as long as you are willing to accept some
JC> limitations on stage trajectory and aspect ratio. I contend that
JC> these are worthwhile tradeoffs.

We could go on for a long time if you enjoy this topic.

AN> ...The best design for the second stage is my engine cluster... Its
AN> description is posted at:
AN> http://www.islandone.org/LEOBiblio/SPBI101.HTM#engine_cluster

JC> Qantity and replication are easy in a spreadsheet or CAD program. It
JC> is a little more troublesome in the real world. We recently made out
JC> lives much, much better by moving from four differentially throttled
JC> engines to a single larger engine with jet vanes. At some point mass
JC> production effects can kick in, but it isn't in the development stage.

There is huge difference between making the rocket by hand and
making it by a robot.

Before the Civil War guns were made by gunsmiths. Their parts
were not interchangeable because the gunsmiths could not make
identical parts by hand. Making the rockets by hand takes lots
of time, and quality control is difficult -- you have to inspect
every weld because one bad weld can ruin your rocket.

Most of the Agena rocket engine was made by a robot -- coolant
passages were drilled in a monolithic slab of aluminum alloy.
My engine cluster has similar design -- it can be made by a
milling robot. The robot is cheaper than the rocket plumber,
and the engine is so sturdy that it may survive the hard VTVL
landing. You do not have to worry about weak welds -- there are
very few of them. Fabrication quality is determined by your CAD
drawing rather than by the robot. Even if you make just one
rocket, it is cheaper to make it by the milling robot than by
hand. I do not know if standard robots can make the narrow
injection nozzle holes, but they can certainly make all the
other holes.

JC> You can't design a high aspect ratio vehicle, but again, it doesn't
JC> really matter for a booster stage. Make it squat, and let the upper
JC> stage be a sphere if it wants to. Go ahead and be highly non-optimal
JC> in the aerodynamics and staging fraction if it gets you good
JC> operability. A booster like this would be a cargo elevator to 100km
JC> or so. Up and down on the hour if you wanted to.

Can you comment on stacking the engines sideways?
(http://www.islandone.org/LEOBiblio/SPBI1010.JPG)
I believe that having lots of engines covering
large area of the rocket is a good idea because
it improves thrust, specific impulse, or both.

JC> Most of the fundamental complexity of a rocket stage is independent of
JC> stage performance. Lots more stages will give lots more problems.
JC> Pushing performance requirements to the edge can easily give even more
JC> problems, which is why I'm not an advocate of a completely SSTO
JC> design, but two stages is going to be both more reliable and easier to
JC> develop and test than more stages.

I have seen lots of comments about problems caused by large
number of stages, but I do not understand these problems.
It seems to me that when you stack identical rocket stages
like Lego blocks, your only problem is designing the
explosive bolts which hold the stages together.

JC> An upper stage from us would probably use 98% peroxide and kerosene.

Other good choices are H2O2/RP-1 and H2O2/propylene.
They are easy to store, but, to the best of my knowledge,
their critical pressures and critical temperatures are high.
If the coolant pressure is lower than its critical pressure,
bubbles may form in the coolant.

If you use oxygen/methane instead of H2O2/RP-1, the payload
mass will increase by about 50% and it will be easier to
cool the engine. Methane can be extracted from natural gas,
so it is cheap and easily available. Propellant tanks holding
liquid oxygen and liquid methane are covered with natural
thermal insulation in the form of frost. Oxygen and methane
have similar boiling point temperatures, so there are no
problems with a propellant freezing in a pipe.

JC> Probably still pressure fed, but at a tank pressure of only
JC> 100 psi or less, which doesn't hurt it much in vacuum operation.

100 psi = 6.9 bars
That is pretty low pressure. (Russian RD-170 engine has the chamber
pressure of 245 bars). Low pressure means high mass ratio, but the
engine must have large exhaust nozzle exit area to produce high
thrust and high specific impulse. Again, the engine cluster looks
like the right choice.

JC> A gas-and-go RLV would be a huge advance even if it used TEN TIMES
JC> the propellant that a conventional rocket used for a given amount of
JC> propellant.

I agree.
John Carmack
2004-06-25 09:50:03 UTC
Permalink
Post by Andrew Nowicki
Yes, VTVL (vertical takeoff and vertical landing on dry land without
parachute and without wings) is the cheapest option and probably the
best one if the rocket is sturdy enough to survive hard landing
without catastrophic damage. (Russian landing retrorockets malfunctioned
several times.)
The Russians see hard landings on Soyus sometimes because they are
using solid rockets. A proper throttling liquid engine should
reliably set down quite softly once the system is fully operational.
If it fails the landing in some way, it probably won't be just a
slightly bigger bump... Not that I advise making fragile vehicles,
but VTVL should allow the most optimized structures of any recovery
mode if you chose to push it.
Post by Andrew Nowicki
JC> Qantity and replication are easy in a spreadsheet or CAD program. It
JC> is a little more troublesome in the real world. We recently made out
JC> lives much, much better by moving from four differentially throttled
JC> engines to a single larger engine with jet vanes. At some point mass
JC> production effects can kick in, but it isn't in the development stage.
There is huge difference between making the rocket by hand and
making it by a robot.
Before the Civil War guns were made by gunsmiths. Their parts
were not interchangeable because the gunsmiths could not make
identical parts by hand. Making the rockets by hand takes lots
of time, and quality control is difficult -- you have to inspect
every weld because one bad weld can ruin your rocket.
Most of the Agena rocket engine was made by a robot -- coolant
passages were drilled in a monolithic slab of aluminum alloy.
My engine cluster has similar design -- it can be made by a
milling robot. The robot is cheaper than the rocket plumber,
and the engine is so sturdy that it may survive the hard VTVL
landing. You do not have to worry about weak welds -- there are
very few of them. Fabrication quality is determined by your CAD
drawing rather than by the robot. Even if you make just one
rocket, it is cheaper to make it by the milling robot than by
hand. I do not know if standard robots can make the narrow
injection nozzle holes, but they can certainly make all the
other holes.
I am a big believer in CNC machining, and we often have large batches
of engine parts made at once. With CNC, the complexity of a single
monolithic part is indeed of little relevence. The problems are still
in the interconnection of the parts. All of our old engine shells
were CNC machined, and it was no more effort to get a dozen of them
than it was to get one of them. On the other hand, it was still
nearly four times as much work to assemble catalyst packs for four of
them, bolt them together, plumb them up, fix the leaks, and so on. We
always wound up with one engine that was somewhat weaker than the
others, and related problems.

Even the best modern machining centers still aren't "part printers",
and you have to think carefully about which manufacturing processes
you use. We do far more manual welding than CNC machining, and the
large structural parts are made by a separate metal rolling shop. The
gun drilled nozzle on the Agena was a very tiny part of the total work
that went into the stage, let alone the vehicle. There have been
improvements since then (filament winding is vastly better in many
ways than classic tank welding), but there is so much work actually in
the details that aren't seen from a high level design view that it is
still nowhere close to "building by robot". I have spent days doing
nothing but making cables.

I do the CNC milling for Armadillo, at least when we are working in
aluminum. There are a many, many times when we slap something
together at the shop with the band saw, drill press, and welder that I
realize would have taken me several times longer to make on the CNC
mill, even if I had the stock on hand. Sure, it's great when I need
to go back and make more copies of it, but for building a prototype, I
wouldn't trade our welders for the best CNC robot in the world.
Post by Andrew Nowicki
JC> You can't design a high aspect ratio vehicle, but again, it doesn't
JC> really matter for a booster stage. Make it squat, and let the upper
JC> stage be a sphere if it wants to. Go ahead and be highly non-optimal
JC> in the aerodynamics and staging fraction if it gets you good
JC> operability. A booster like this would be a cargo elevator to 100km
JC> or so. Up and down on the hour if you wanted to.
Can you comment on stacking the engines sideways?
(http://www.islandone.org/LEOBiblio/SPBI1010.JPG)
I believe that having lots of engines covering
large area of the rocket is a good idea because
it improves thrust, specific impulse, or both.
We are actually building a micro-nozzle plate, so you may have some
real pictures to point to in a month or so. The reason we are looking
at it is to save vehicle height over a single nozzle and reduce issues
with flow separation from overexpanded nozzles -- lots of little
nozzles will not all separate in the same direction.

For the same total throat area and expansion ratio, multiple small
nozzles will likely offer slightly worse performance, but they may
allow you to package a higher expansion ratio than you could
otherwise. You will certainly need to be able to throttle at least
banks of the engines separately for steering, and you will need either
dedicated roll engines, or a cant to some of the main engines for roll
control.
Post by Andrew Nowicki
JC> Most of the fundamental complexity of a rocket stage is independent of
JC> stage performance. Lots more stages will give lots more problems.
JC> Pushing performance requirements to the edge can easily give even more
JC> problems, which is why I'm not an advocate of a completely SSTO
JC> design, but two stages is going to be both more reliable and easier to
JC> develop and test than more stages.
I have seen lots of comments about problems caused by large
number of stages, but I do not understand these problems.
It seems to me that when you stack identical rocket stages
like Lego blocks, your only problem is designing the
explosive bolts which hold the stages together.
You still have to build them, and any given chance of failure in the
parts will add up. Obviously two identical stages are easier than two
different stages, but it isn't at all obvious that six identical
stages are easier than two different stages.
Post by Andrew Nowicki
JC> An upper stage from us would probably use 98% peroxide and kerosene.
Other good choices are H2O2/RP-1 and H2O2/propylene.
They are easy to store, but, to the best of my knowledge,
their critical pressures and critical temperatures are high.
If the coolant pressure is lower than its critical pressure,
bubbles may form in the coolant.
Peroxide is a very good coolant, and you have lots of it compared to a
fuel, so for a decent sized engine, you won't even get the peroxide to
the boiling point.
Post by Andrew Nowicki
JC> Probably still pressure fed, but at a tank pressure of only
JC> 100 psi or less, which doesn't hurt it much in vacuum operation.
100 psi = 6.9 bars
That is pretty low pressure. (Russian RD-170 engine has the chamber
pressure of 245 bars). Low pressure means high mass ratio, but the
engine must have large exhaust nozzle exit area to produce high
thrust and high specific impulse. Again, the engine cluster looks
like the right choice.
That ties in with the low aspect ratio booster. A big fat upper stage
can sit on top of it. It may wind up with something like a giant
aerospike covering the entire bottom of a spherical or flatter tank.

John Carmack
www.armadilloaerospace.com
Andrew Nowicki
2004-06-25 20:02:22 UTC
Permalink
John Carmack wrote:

JC> Peroxide is a very good coolant, and you have
JC> lots of it compared to a fuel, so for a decent
JC> sized engine, you won't even get the peroxide to
JC> the boiling point.

You are right! I have been thinking about
supercritical oxygen/methane, but H2O2/RP-1
has four times greater density -- no contest.

AN> ... the engine must have large exhaust nozzle
AN> exit area to produce high thrust and high
AN> specific impulse. Again, the engine cluster
AN> looks like the right choice.

JC> That ties in with the low aspect ratio booster.
JC> A big fat upper stage can sit on top of it. It
JC> may wind up with something like a giant aerospike
JC> covering the entire bottom of a spherical or flatter
JC> tank.

JC> For the same total throat area and expansion ratio,
JC> multiple small nozzles will likely offer slightly
JC> worse performance, but they may allow you to package
JC> a higher expansion ratio than you could otherwise.
JC> You will certainly need to be able to throttle at
JC> least banks of the engines separately for steering,
JC> and you will need either dedicated roll engines, or
JC> a cant to some of the main engines for roll control.

This is the most interesting part of our conversation.
What is the best design for the second stage: squat
shape with the engine in its bottom, or slender shape
with several engines or several hundred engines covering
its side, like the rocket cluster? I prefer the latter,
not only because of better performance (expansion ratio,
etc.) but also because the slender shape generates less
atmospheric drag on the way up.

It is not clear which shape is better for the reentry.
The slender rocket can reenter either nose cone first,
or it can reenter sideways. I am thinking about a
slender rocket which reenters sideways while it spins
about its axis at about 10 revolutions per second.
The spinning rocket radiates heat in all directions,
so it may not need the expensive heat shield.
Andrew Nowicki
2004-06-26 00:19:40 UTC
Permalink
Andrew Nowicki wrote:

AN> ...I am thinking about a slender rocket which reenters
AN> sideways while it spins about its axis at about 10
AN> revolutions per second. The spinning rocket radiates
AN> heat in all directions, so it may not need the
AN> expensive heat shield.

The image of the spinning second stage is posted at:
Loading Image...

Note that the center of mass of the spinning stage
must be close to its center of volume. If the second
stage has only one engine located on its end, this
end will be more massive than the other end, and the
second stage will reenter the atmosphere engine end
first.
Phil Fraering
2004-06-27 04:49:14 UTC
Permalink
Post by John Carmack
We are actually building a micro-nozzle plate, so you may have some
real pictures to point to in a month or so. The reason we are looking
at it is to save vehicle height over a single nozzle and reduce issues
with flow separation from overexpanded nozzles -- lots of little
nozzles will not all separate in the same direction.
Have you considered using an annular or plug nozzle instead?
--
pgf
Vincent Cate
2004-06-23 21:09:46 UTC
Permalink
Post by Earl Colby Pottinger
http://media.armadilloaerospace.com/2004_06_15/perfectBoostedHop.mpg
An actual pressure fed rocket with almost no moving parts doing a
powered landing. It is my considered opinion that this is The Right
Way To Do It. Build a big, simple booster that lofts a high
performance upper stage all the way out of the atmosphere, then
returns to land on the same pad it took off from.
The video is very impressive, and very fun. Congrats!

For powered accent and decent, having aerodynamic stability
forward and backward seems a bit tricky. Using active
controls is fine for a short and slow flight, but for a long
and fast flight it seems like you really want aerodynamic
stability.

Assuming you are not moving any fins or changing shape to
change your center of drag, you would have to do this by
changing your center of mass. You do have a lot more fuel
mass when you are on the way up, so your center of mass
can be higher. On the way down your tanks are closer to
empty, so the fixed mass of the engines would shift the
center of mass lower. If you transition between a high
center of mass and a low center of mass when you are above
most of the atmosphere, things could work out. Is this
what Armadillo is planning?

Idling the engines for most of the way down would mean
you don't have as much trouble with reentry heat, since you
are sort of doing transpiration. Yet you would not need
a huge amount of fuel, since really it was still drag doing
the work on the way down (and your total mass is much less).

I think powered landing is surprisingly reasonable. :-)

-- Vince
Earl Colby Pottinger
2004-06-24 05:59:44 UTC
Permalink
Post by Vincent Cate
Idling the engines for most of the way down would mean
you don't have as much trouble with reentry heat, since you
are sort of doing transpiration. Yet you would not need
a huge amount of fuel, since really it was still drag doing
the work on the way down (and your total mass is much less).
Important point, once the engines are warmed up Armadillo seem to have no
problem with restarts. So in coming down most of the trip can be done in
free fall and the engines only fired up once they are close to earth. This
saves on fuel needed.

Earl Colby Pottinger
--
I make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos,
SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to
the time? http://webhome.idirect.com/~earlcp
Vincent Cate
2004-06-24 12:28:31 UTC
Permalink
Post by Earl Colby Pottinger
Post by Vincent Cate
Idling the engines for most of the way down would mean
you don't have as much trouble with reentry heat, since you
are sort of doing transpiration. Yet you would not need
a huge amount of fuel, since really it was still drag doing
the work on the way down (and your total mass is much less).
Important point, once the engines are warmed up Armadillo seem to have no
problem with restarts. So in coming down most of the trip can be done in
free fall and the engines only fired up once they are close to earth. This
saves on fuel needed.
True. You might choose to run the engines during peak heating just
to reduce the amount of heat that gets to the vehicle.

-- Vince
Vincent Cate
2004-06-24 12:33:22 UTC
Permalink
Post by Vincent Cate
On the way down your tanks are closer to
empty, so the fixed mass of the engines would shift the
center of mass lower.
For a suborbital passenger vehicle you could put the people
just above the engines and below the tanks so that their
fixed mass was also low. This is not an issue for a
the booster lifting another stage that goes on to orbit.

-- Vince
John Carmack
2004-06-24 19:15:37 UTC
Permalink
Post by Vincent Cate
Assuming you are not moving any fins or changing shape to
change your center of drag, you would have to do this by
changing your center of mass. You do have a lot more fuel
mass when you are on the way up, so your center of mass
can be higher. On the way down your tanks are closer to
empty, so the fixed mass of the engines would shift the
center of mass lower. If you transition between a high
center of mass and a low center of mass when you are above
most of the atmosphere, things could work out. Is this
what Armadillo is planning?
Our vehicles should be aerodynamically stable in decent, but need to
be actively controlled on ascent. All of our short flights will be
pwoered both up and down, but when we start doing our waivered flights
we will sneak our way into having the engines shut down on descent.
The actual algorithm is that once the timed boost phase completes, the
vehicle adjusts the engine until the vehicle is seeing a given
acceleration. The last test was very conservative, with the minimum
acceleration set at +0.5G, or half a G of decelleration. If we just
shtu the throttle down, propellant wouold fly away from the tank
outlet, and we would lose control. The test flight didn't get going
fast enough to show it, but if the vehicle went high enough,
eventually the aerodynamic drag on the way down would provide the
minimum acceleration and the engine would throttle itself down. It is
our intention to feel this transition out very gently, because we
don't know how bad the vehicle will oscillate under only aerodynamic
loads. We might wind up sticking some DC-X style strakes on the nose
to give it a bit better descent stability.
Post by Vincent Cate
Idling the engines for most of the way down would mean
you don't have as much trouble with reentry heat, since you
are sort of doing transpiration. Yet you would not need
a huge amount of fuel, since really it was still drag doing
the work on the way down (and your total mass is much less).
Reentry heat for a suborbital vehicle is pretty much a non-issue. The
engines get much hotter while operating than the relatively mild
suborbital reentry heat pulse. The base of the vehicle is just going
to have a layer of RTV over everything.

John Carmack
www.armadilloaerospace.com
Vincent Cate
2004-06-26 01:07:43 UTC
Permalink
Post by John Carmack
Our vehicles should be aerodynamically stable in decent, but need to
be actively controlled on ascent.
The failure mode of loosing propulsion during ascent would be
less problematic if you were also stable during ascent. It seems
like you really could design the rocket so that the fuel makes your
center of mass forward of the center of drag on the way up and
the engines/people made the center of mass below the center of
drag when you had empty tanks on the way down. Seems like it
would be worth doing.

Some people might not like riding between the engines and the
fuel tanks. But you don't need to please everyone.

Will people have parachutes and the possibility of leaving
the vehicle in certain types of abort?

-- Vince
Vincent Cate
2004-06-27 17:47:06 UTC
Permalink
Post by Vincent Cate
Will people have parachutes and the possibility of leaving
the vehicle in certain types of abort?
I took a few flying lessons in a Citabria stunt plane and was
required to wear a parachute (I flew a loop my first time out!).
So to me wearing a parachute on a suborbital rocket ride seems
reasonable. But the design of the rocket would determine how
much use this would really be. With a low enough terminal
velocity, personal parachutes could be a good backup.

-- Vince
Christopher M. Jones
2004-06-24 06:51:46 UTC
Permalink
Post by Earl Colby Pottinger
http://media.armadilloaerospace.com/2004_06_15/perfectBoostedHop.mpg
An actual pressure fed rocket with almost no moving parts doing a
powered landing. It is my considered opinion that this is The Right
Way To Do It. Build a big, simple booster that lofts a high
performance upper stage all the way out of the atmosphere, then
returns to land on the same pad it took off from. At first flance it
sounds like an inefficient staging strategy, since the upper stage
requires nearly SSTO dV, but removing the requirment of boosting
through the atmosphere (optimize only for vaccuum boost and reentry)
does still simplify the problem quite a bit, and the operational and
testing aspects are great.
Not an especially bad idea. Of especially consideration
are, on the plus side, greatly eased aerodynamic
considerations on the launch vehicle as well as perfomance
improvement on of the near-SSTO main engine in vacuum.
On the minus side though there are large gravity losses,
vehicle sizing issues, and characteristic minimum boost
times to deal with. Which make up for some of the
disadvantages. At the minimum it's a workable interim
solution that makes progression toward lean, mean, SSTO
launching machines slightly easier. I guess this would be
a "bigger dumber stage" concept.

Let me expand on some of the issues here. First is
aerodynamics, modern launch vehicles travel at supersonic
and even hypersonic speeds during launch. This places
constraints on payloads and especially payload packaging,
which can steal from raw payload capability by requiring
strong payload attachments and aerodynamic fairings, which
take up mass. This also brings into play a great deal of
vibrational energy, which the payload has to survive once
and only once to get to orbit but never after. Which
requires designing and testing the spacecraft carefully
to make sure it will survive a launch, things that usually
do not come free, or even cheap. However, a "pop-up and
boost" launch vehicle would have a much different flight
profile. Theoretically the portion of the pop-up flight
within the atmosphere could be at rather unimpressive
speeds, such as low mach numbers, or even sub-sonic. At
mach 1 it takes only a few minutes to climb out of the bulk
of the atmosphere. Raw gee forces will almost necessarily
still be a concern, as the pop-up booster still has to
avoid throwing away all its fuel to gravity and the near
SSTO still has to climb into orbit before reentering.
Nevertheless, steady gee forces are much, much easier to
deal with mechanically than vibrations and lurches, and
with liquid propulsion systems on all stages it's possible
for a pop-up booster to give satellites or other cargo an
incredibly gentle ride. This is no small issue, because
engineering fragile spacecraft to be able to survive the
rigors of launch is a huge cost sink, this could
potentially make low-cost satellites much more feasible.

Working only in low pressure or vacuum can provide
substantial performance improvements for a rocket engine.
Roughly about a 10% improvement in Isp for LOX/Kero
engines and up to a 25% improvement in Isp for LOX/LH2
engines. For Kerosene engines, this is enough of an
improvement to bring the delta V/Isp side of the equation
into overlap with the achievable dry mass fraction side,
with a bit of margin as well. Additionally, depending on
how much time the pop-up booster gives the launcher to get
into orbit the necessary thrust to weight ratios could be
lowered as well, allowing for lower engine weight and
easing some throttling issues (if you start off with a
thrust/weight of less than 1 gee then the inevitable
problems of high gees or very deep throttling in a LOX/Kero
booster near burnout become much less of a concern).

With those two factors added together, if we *had* a bigger,
dumber, pop-up booster now we could quite easily put SSTO
capable vehicles on them using very prosaic engineering
(60s vintage). With a few tweaks (such as modern
electronics, more finely honed structures, modern alloys,
and composite structures) we could almost certainly build in
enough margin to add the bits that would make it reusible
(like TPS).

The downsides are worth considering though. First, gravity
losses are going to be big, and pretty much all the
propellant used by the pop-up booster will at least appear
to be entirely wasted in terms of getting to orbit. The
good news is that this is a propellant issue, and propellant
is dirt cheap compared to orbital launch costs, so it's a
non-issue with respect to operations today, but won't be
competitive in the long term when ground launched SSTOs
can operate at low multiples of propellant cost (may we some
day be blessed with such a "problem"). Second, the real
concern is the sheer size of the booster. SSTOs are almost
inevitably rather bulky with high GLOWs. The pop-up booster
has to be big enough to take that beast a couple hundred km
straight up. And that means it has to be absolutely
gargantuan. The thrust on it ought to be quite impressive.
The good news though is that it can be made very low tech,
and metal, or even concrete, and propellants are cheap.


As a concept design, imagine something along the lines of
a Saturn-V first stage with a fixed payload bay and crew
compartment(s) above the tanks, as well as TPS and landing
systems and such like here and there, with slightly fewer,
lower thrust engines. Now imagine this connected to the
mother of all brick sh*t-houses with a small horde of the
most powerful engines in the world on the underside. I'd
imagine the pop-up booster on this beast would have a
"payload bay / shroud" more similar to an aircraft hangar
than anything else. It would be impressive at the very
least.
Andrew Nowicki
2004-06-24 17:11:11 UTC
Permalink
"Christopher M. Jones" wrote:

CMJ>...However, a "pop-up and boost" launch vehicle would have
CMJ> a much different flight profile. Theoretically the
CMJ> portion of the pop-up flight within the atmosphere could
CMJ> be at rather unimpressive speeds, such as low mach numbers,
CMJ> or even sub-sonic. At mach 1 it takes only a few minutes
CMJ> to climb out of the bulk of the atmosphere. Raw gee forces
CMJ> will almost necessarily still be a concern, as the pop-up
CMJ> booster still has to avoid throwing away all its fuel to
CMJ> gravity and the near SSTO still has to climb into orbit
CMJ> before reentering. Nevertheless, steady gee forces are much,
CMJ> much easier to deal with mechanically than vibrations and
CMJ> lurches, and with liquid propulsion systems on all stages
CMJ> it's possible for a pop-up booster to give satellites or
CMJ> other cargo an incredibly gentle ride...

True.

CMJ> The pop-up booster has to be big enough to take that
CMJ> beast a couple hundred km straight up.

False. When the altitude is increased by 20 kilometers,
atmospheric pressure drops about 10 times. You can
ignore atmospheric drag above the altitude of 40 km.

The precise formula for atmospheric pressure is:
p = B(exp(-MgY/RT)), Where:

p = pressure at elevation Y
B = pressure at elevation zero
exp = natural exponent
M = molecular mass, or mass in kg per mol
(M = 0.0288 kg/mol for dry air)
g = acceleration due to gravity = 9.8 m/s^2
R = gas constant = 8.314 J/(mol*K)
T = absolute temperature (in Kelvins) = about 273 K
Henry Spencer
2004-06-19 22:07:06 UTC
Permalink
Post by Andrew Nowicki
The Mojave Airport is a perfect place to test
airplanes and sounding rockets, but it is probably
the worst place on Earth to locate the space rocket
launch site -- Manhattan would be better.
Hardly. Mojave *is* out in the middle of nowhere, which is why a lot of
aircraft testing already gets done there. The biggest hazards from
rocketry are in the immediate vicinity of the launch site.
Post by Andrew Nowicki
There is no ocean to the east of Mojave, so you cannot make
cheap pressure-fed rockets, splash them down and
reuse them.
You couldn't do that from Mojave Spaceport anyway, because (last I heard)
their spaceport license is for horizontal-takeoff-horizontal-landing
launch vehicles only. They've decided to cater to one particular type of
vehicle, rather than covering the whole spectrum.

If you're going to build vehicles resembling artillery rockets, where
pieces deliberately fall off during ascent and make uncontrolled landings,
then quite likely you are going to have to launch over water. That's not
the only design option.
Post by Andrew Nowicki
A big city (Los Angeles) is just 100 km south of Mojave.
Orlando is about the same distance from the Cape, and Vandenberg is not
much farther away from L.A.
Post by Andrew Nowicki
If you launch the real thing, you will have to launch it
in the south west direction and hope it will not fall on Los Angeles.
No, you launch eastward, and establish sufficiently low probability of
casualties by good design and proper testing. (Operating only over
largely uninhabited areas certainly *helps* -- it means you can achieve
the required level of safety even with a relatively high estimated
probability of failure, which is easier to justify -- but it is not
actually required.)

Note that there is no launch site on Earth where your debris footprint
will be on water throughout ascent. Even launching from the Cape, some
possibility of hitting Africa must be accepted.
Post by Andrew Nowicki
NASA should make the Kennedy Space Center available
to independent rocket makers.
The Cape is already available to commercial rocket builders, and has been
for quite a while. The bureaucratic hurdles are considerable -- and they
would not get easier at KSC, because the USAF is in charge of range safety
either way -- and the overhead costs are high, but it is available.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert | ***@spsystems.net
Andrew Nowicki
2004-06-20 02:10:56 UTC
Permalink
Andrew Nowicki <***@nospam.com> wrote:

AN> There is no ocean to the east of Mojave,
AN> so you cannot make cheap pressure-fed rockets,
AN> splash them down and reuse them.

Henry Spencer wrote:

HS> You couldn't do that from Mojave Spaceport anyway,
HS> because (last I heard) their spaceport license is
HS> for horizontal-takeoff-horizontal-landing launch
HS> vehicles only. They've decided to cater to one
HS> particular type of vehicle, rather than covering
HS> the whole spectrum... you launch eastward...

Single stage rocket launchers do not exist. Does it
mean that the spent first stage is dropped near
Phoenix, Arizona, and the spent second stage is
dropped on Texas?
Christopher M. Jones
2004-06-20 03:09:25 UTC
Permalink
Post by Andrew Nowicki
Single stage rocket launchers do not exist. Does it
mean that the spent first stage is dropped near
Phoenix, Arizona, and the spent second stage is
dropped on Texas?
Actually, single stage rocket launchers do exist.
As do rockets with entirely reusible stages
throughout. Single stage *orbital* launchers do
not, but nobody's flying those out of Mojave any
time soon so that's a non-issue.
Henry Spencer
2004-06-20 02:59:13 UTC
Permalink
Post by Andrew Nowicki
HS> You couldn't do that from Mojave Spaceport anyway,
HS> because (last I heard) their spaceport license is
HS> for horizontal-takeoff-horizontal-landing launch
HS> vehicles only...
Single stage rocket launchers do not exist.
Neither do the pressure-fed launchers you're talking about.
Post by Andrew Nowicki
Does it mean that the spent first stage is dropped near
Phoenix, Arizona...
No, its pilot turns it around and flies it back to base. Or, possibly,
glides it down to a landing at some suitable airstrip, from which it is
trucked or flown back to Mojave, although that's rather less convenient.
What part of "horizontal-takeoff-horizontal-landing only" is so hard for
you to grasp?

Your pressure-fed artillery rockets will *never* operate out of Mojave,
and it's got nothing to do with where the pieces falling off would land.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert | ***@spsystems.net
Andrew Nowicki
2004-06-20 17:53:00 UTC
Permalink
Andrew Nowicki <***@nospam.com> wrote:
AN> Does it mean that the spent first stage is
AN> dropped near Phoenix, Arizona...

Henry Spencer wrote:
HS> No, its pilot turns it around and flies it back
HS> to base. Or, possibly, glides it down to a landing
HS> at some suitable airstrip, from which it is trucked
HS> or flown back to Mojave, although that's rather less
HS> convenient.

HS> What part of "horizontal-takeoff-horizontal-landing
HS> only" is so hard for you to grasp?

Russian Baikal is a winged, reusable first stage which
is going to be a part of a two stage launcher. Russia
is almost a landlocked country, so they have no choice
but to make the winged first stage. (They would like
to make a spaceport in French Guiana.) A pressure-fed
splashdown rocket is much simpler and cheaper than the
Baikal. This is why a spaceport on the Atlantic coast
makes sense, but the spaceport in the landlocked Mojave
airport does not make sense.

If I am wrong, NASA, Boeing, Lockheed Martin, and the
likes will flock to the Mojave airport.

HS> Your pressure-fed artillery rockets will *never*
HS> operate out of Mojave, and it's got nothing to do
HS> with where the pieces falling off would land.

The pressure-fed rockets can have foldable wings, jet
engines, landing gear, etc., but all this extra hardware
is far more expensive and less reliable than the rockets.
Henry Spencer
2004-06-20 21:44:26 UTC
Permalink
Post by Andrew Nowicki
HS> What part of "horizontal-takeoff-horizontal-landing
HS> only" is so hard for you to grasp?
Russian Baikal is a winged, reusable first stage which
is going to be a part of a two stage launcher...
Russia is almost a landlocked country, so they have no choice
but to make the winged first stage.
Sure they have. They were planning to recover the Energia first stage
(the strap-ons) with parachutes.

For that matter, Kistler planned to launch from Nevada, and recover its
first stage -- at the launch site, after a post-staging turnaround burn --
with parachutes and airbags.
Post by Andrew Nowicki
...A pressure-fed
splashdown rocket is much simpler and cheaper than the Baikal.
Simpler and cheaper to build, yes. But as for simpler and cheaper to
operate... the verdict has to be "not proven".
Post by Andrew Nowicki
This is why a spaceport on the Atlantic coast
makes sense, but the spaceport in the landlocked Mojave
airport does not make sense.
You're assuming that your favorite configuration is the only workable one.
Whether or not it is the *best* -- a distinctly arguable point -- there
are a number of alternatives which should work too, some of which could
fly from Mojave.
Post by Andrew Nowicki
If I am wrong, NASA, Boeing, Lockheed Martin, and the
likes will flock to the Mojave airport.
Why should they? Their launch systems all use vertical takeoff, and thus
cannot legally operate from Mojave. Moreover, those systems all bring
their spent stages down uncontrolled and far downrange, which means it is
most unlikely that they would be licensed to operate there.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert | ***@spsystems.net
George William Herbert
2004-06-21 00:15:02 UTC
Permalink
Post by Henry Spencer
Post by Andrew Nowicki
If I am wrong, NASA, Boeing, Lockheed Martin, and the
likes will flock to the Mojave airport.
Why should they? Their launch systems all use vertical takeoff, and thus
cannot legally operate from Mojave.
I suspect that the FAA could be convinced to allow moderate sized VT and
VL operations from Mojave spaceport, though the paperwork so far does
not allow for it.

The killer problem is that Mojave *port is not isolated enough
for *large* rocket operations, Horizontal takeoff or not.
There's a town with several thousand people right up against the
side of the *port. There's a freeway nearby. The *port itself
is full of people and expensive stuff well within the danger
zone if, for example, a large rocket fell over and exploded
(which is a risk with any launch mode, and reusable or expendables).
With oxidizer on board there is larger risk than just large
fueled aircraft.

I think that Armadillo Aerospace's vehicle would probably still
be within reasonable safety margins; with people on board,
the risk of it coming down in town is not a lot more than
that of a large jetliner sized experimental aircraft,
and the damage potential probably comparable. Someone would
have to work out the various impact damage assessments
in detail though.

Launching any serious orbital mission would probably
be right out, though. An air-launched vehicle which
was transported by aircraft further away from the
city of Mojave isn't all that much of a risk,
because the odds of a takeoff accident are so
remote with a jetliner, but a ground launch of
any rocket, even fully reusable ssto manned with
wings and all, is much riskier for the forseeable
future.


-george william herbert
***@retro.com
Edward Wright
2004-06-28 19:42:27 UTC
Permalink
The *port itself is full of people and expensive stuff well within the danger
zone if, for example, a large rocket fell over and exploded
(which is a risk with any launch mode, and reusable or expendables).
When was the last time a large airplane fell over and exploded? Or
just fell over, period? This is surely not a likely failure mode for
HTHL vehicles.
Sander Vesik
2004-06-21 11:10:38 UTC
Permalink
Post by Andrew Nowicki
AN> Does it mean that the spent first stage is
AN> dropped near Phoenix, Arizona...
HS> No, its pilot turns it around and flies it back
HS> to base. Or, possibly, glides it down to a landing
HS> at some suitable airstrip, from which it is trucked
HS> or flown back to Mojave, although that's rather less
HS> convenient.
HS> What part of "horizontal-takeoff-horizontal-landing
HS> only" is so hard for you to grasp?
Russian Baikal is a winged, reusable first stage which
is going to be a part of a two stage launcher. Russia
is almost a landlocked country, so they have no choice
but to make the winged first stage. (They would like
Oh? Well, guess what, the country from which Soyus presently
launches is entirely land-locked and it does not have wings on
any stage.
Post by Andrew Nowicki
to make a spaceport in French Guiana.) A pressure-fed
splashdown rocket is much simpler and cheaper than the
Baikal. This is why a spaceport on the Atlantic coast
makes sense, but the spaceport in the landlocked Mojave
airport does not make sense.
There is no Russian launcher by the name "Baikal" AFAIK.
Maybe you are thinking of Buran?
Post by Andrew Nowicki
If I am wrong, NASA, Boeing, Lockheed Martin, and the
likes will flock to the Mojave airport.
You are wrong in too many ways for your righness or
wrongness to matter.
Post by Andrew Nowicki
HS> Your pressure-fed artillery rockets will *never*
HS> operate out of Mojave, and it's got nothing to do
HS> with where the pieces falling off would land.
The pressure-fed rockets can have foldable wings, jet
engines, landing gear, etc., but all this extra hardware
is far more expensive and less reliable than the rockets.
well yes, and given sufficent thrust even pigs fly. so what?
--
Sander

+++ Out of cheese error +++
Henry Spencer
2004-06-21 17:41:21 UTC
Permalink
Post by Sander Vesik
There is no Russian launcher by the name "Baikal" AFAIK.
Maybe you are thinking of Buran?
No, Baikal is a proposal for (if I haven't mixed it up with another paper
rocket) a winged flyback version of the Angara first stage.

Angara is a real project, although chronically short of funding. Baikal
is just pretty pictures at present.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert | ***@spsystems.net
Sander Vesik
2004-06-21 21:06:25 UTC
Permalink
Post by Henry Spencer
Post by Sander Vesik
There is no Russian launcher by the name "Baikal" AFAIK.
Maybe you are thinking of Buran?
No, Baikal is a proposal for (if I haven't mixed it up with another paper
rocket) a winged flyback version of the Angara first stage.
Angara is a real project, although chronically short of funding. Baikal
is just pretty pictures at present.
I see. Too many different russian projects starting in 'b' :(
--
Sander

+++ Out of cheese error +++
Sander Vesik
2004-06-20 18:23:32 UTC
Permalink
Post by Andrew Nowicki
HS> You couldn't do that from Mojave Spaceport anyway,
HS> because (last I heard) their spaceport license is
HS> for horizontal-takeoff-horizontal-landing launch
HS> vehicles only. They've decided to cater to one
HS> particular type of vehicle, rather than covering
HS> the whole spectrum... you launch eastward...
Single stage rocket launchers do not exist. Does it
mean that the spent first stage is dropped near
Phoenix, Arizona, and the spent second stage is
dropped on Texas?
Umm... Single stage to orbit not existing / being available doesn't
mean that the stages have to drop down. They could fly back instead.
--
Sander

+++ Out of cheese error +++
John Schilling
2004-06-21 16:39:57 UTC
Permalink
Post by Andrew Nowicki
AN> There is no ocean to the east of Mojave,
AN> so you cannot make cheap pressure-fed rockets,
AN> splash them down and reuse them.
HS> You couldn't do that from Mojave Spaceport anyway,
HS> because (last I heard) their spaceport license is
HS> for horizontal-takeoff-horizontal-landing launch
HS> vehicles only. They've decided to cater to one
HS> particular type of vehicle, rather than covering
HS> the whole spectrum... you launch eastward...
Single stage rocket launchers do not exist. Does it
mean that the spent first stage is dropped near
Phoenix, Arizona, and the spent second stage is
dropped on Texas?
You know, I just watched a space launch from the Mojave
spaceport just under two hours ago. The pilot of the
first stage did a perfectly serviceable job of not hitting
Phoenix by the obvious method of turning around and flying
back for a landing at Mojave.
--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
****@spock.usc.edu * for success" *
*661-718-0955 or 661-275-6795 * -58th Rule of Acquisition *
Chris Manteuffel
2004-06-27 03:39:46 UTC
Permalink
Post by Henry Spencer
Note that there is no launch site on Earth where your debris footprint
will be on water throughout ascent. Even launching from the Cape, some
possibility of hitting Africa must be accepted.
What about south from VAFB? I thought that one of the disadvantages of
the polar orbiting shuttle missions was that there was essentially no
spot for an abort between RTLS and AOA (hence the necessity for high
cross-range, because the AOA abort phase of the card would be a wider
than for an over-the-Atlantic launch). Is Antartica close enough that
it would still be in a potential impact area for debris?

What exactly is the end of the ascent phase on an orbital flight, in
terms of the debris and range-safety? I would think that a FDO would
consider it to be the end of the perigee-raising burn, but when does
range-safety stop worrying about debris impact?

Chris Manteuffel
Edward Wright
2004-06-28 19:31:21 UTC
Permalink
Post by Henry Spencer
You couldn't do that from Mojave Spaceport anyway, because (last I heard)
their spaceport license is for horizontal-takeoff-horizontal-landing
launch vehicles only. They've decided to cater to one particular type of
vehicle, rather than covering the whole spectrum.
I'm not sure if "decided" is the right word. Getting FAA approval for
a VTOL spaceport is somewhere more difficult. The impact point for
suborbital VTOLs tends to dwell near the vicinity of the spaceport, so
meeting the expected casualty requirement is more challenging if
there's anything in the vicinity of the spaceport. I presume Mojave
didn't bother because they have no potential VTOL customers at
present. If such customers showed up, and they felt their chances of
success warranted the effort, they might pursue changes to their FAA
license to permit VTOL launches.
Joann Evans
2004-06-20 02:22:51 UTC
Permalink
Post by Andrew Nowicki
The Mojave Airport is a perfect place to test
airplanes and sounding rockets, but it is probably
the worst place on Earth to locate the space rocket
launch site -- Manhattan would be better. There is
no ocean to the east of Mojave, so you cannot make
cheap pressure-fed rockets, splash them down and
reuse them. A big city (Los Angeles) is just 100 km
south of Mojave. The nearest pacific coast is 130 km
south west, next to Ventura, California. If you
launch the real thing, you will have to launch it
in the south west direction and hope it will not
fall on Los Angeles.
NASA should make the Kennedy Space Center available
to independent rocket makers.
This matters only to those who have to drop expendable stages. Ocean
disposal is irrelevant to an SSTO, or a TSTO with a flyback first stage.
(Which SS1 operationally approxamates as far as 'staging' is concerned.)
--
You know what to remove, to reply....
Brian Thorn
2004-06-20 16:18:36 UTC
Permalink
Post by Andrew Nowicki
NASA should make the Kennedy Space Center available
to independent rocket makers.
Well, remember that KSC and Cape Canaveral are essentially two halves
of the same coin. Beal planned to launch his BA-1 rockets from the old
Complex 19 at the Cape, if memory serves.

Brian
Earl Colby Pottinger
2004-06-20 16:29:33 UTC
Permalink
Post by Andrew Nowicki
The Mojave Airport is a perfect place to test
airplanes and sounding rockets, but it is probably
the worst place on Earth to locate the space rocket
launch site -- Manhattan would be better. There is
no ocean to the east of Mojave, so you cannot make
cheap pressure-fed rockets, splash them down and
reuse them. A big city (Los Angeles) is just 100 km
south of Mojave. The nearest pacific coast is 130 km
south west, next to Ventura, California. If you
launch the real thing, you will have to launch it
in the south west direction and hope it will not
fall on Los Angeles.
You have a strange idea about how pressure-feeded rockets must operate/land.
Please tell why the following pressure feeded rocket would need an ocean to
land in?

http://www.armadilloaerospace.com/
http://www.armadilloaerospace.com/n.x/Armadillo/Home/News?news_id=263

And what is wrong with just landing like this?
http://media.armadilloaerospace.com/2004_06_15/perfectBoostedHop.mpg
Post by Andrew Nowicki
NASA should make the Kennedy Space Center available
to independent rocket makers.
No-one on a budget wants NASA's red tape.

Earl Colby Pottinger
--
I make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos,
SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to
the time? http://webhome.idirect.com/~earlcp
Andrew Nowicki
2004-06-20 17:53:06 UTC
Permalink
Post by Earl Colby Pottinger
You have a strange idea about how pressure-feeded
rockets must operate/land. Please tell why the
following pressure feeded rocket would need an
ocean to land in?
There is a big diference between a sounding rocket
and a rocket launcher. The rocket launcher with
fixed wings (like the Space Shuttle) is a bad idea
because the wings produce too much atmospheric drag
during launch and they heat up during reentry.
Russian Baikal has foldable wings.

This is a matter of economics. All this extra
airplane gear adds weight, cost, and complexity.
Earl Colby Pottinger
2004-06-21 08:35:49 UTC
Permalink
Post by Andrew Nowicki
Post by Earl Colby Pottinger
You have a strange idea about how pressure-feeded
rockets must operate/land. Please tell why the
following pressure feeded rocket would need an
ocean to land in?
There is a big diference between a sounding rocket
and a rocket launcher. The rocket launcher with
fixed wings (like the Space Shuttle) is a bad idea
because the wings produce too much atmospheric drag
during launch and they heat up during reentry.
Russian Baikal has foldable wings.
This is a matter of economics. All this extra
airplane gear adds weight, cost, and complexity.
That was not a sounding rocket. Please read the site.

Earl Colby Pottinger
--
I make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos,
SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to
the time? http://webhome.idirect.com/~earlcp
Eric Chomko
2004-06-22 16:48:44 UTC
Permalink
Andrew Nowicki (***@nospam.com) wrote:
: The Mojave Airport is a perfect place to test
: airplanes and sounding rockets, but it is probably
: the worst place on Earth to locate the space rocket
: launch site -- Manhattan would be better. There is
: no ocean to the east of Mojave, so you cannot make
: cheap pressure-fed rockets, splash them down and
: reuse them. A big city (Los Angeles) is just 100 km
: south of Mojave. The nearest pacific coast is 130 km
: south west, next to Ventura, California. If you
: launch the real thing, you will have to launch it
: in the south west direction and hope it will not
: fall on Los Angeles.

: NASA should make the Kennedy Space Center available
: to independent rocket makers.

Wallops Island in Virginia?

Eric
Andrew Nowicki
2004-06-22 20:53:38 UTC
Permalink
Post by Eric Chomko
Wallops Island in Virginia?
It seems that Wallops is the best:
http://www.wff.nasa.gov/pages/fabrication.html

...but there are other launch sites:
http://www.hobbyspace.com/SpacePorts/spaceports3.html
t***@gmail.com
2012-07-05 03:45:42 UTC
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Alan Erskine
2012-07-05 07:27:52 UTC
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Post by t***@gmail.com
Serving those who need it most! Anytime Restoration is a family operated company built on strong principles that makes recovering from a disaster the least intrusive as possible. We specialize in Storm Damage & Carpet Cleaning Sterling Heights Michigan.
http://www.anytimerestorationservices.com
Such strong principles that you are posting from Bangledesh?
William Elliot
2012-07-05 07:58:23 UTC
Permalink
Post by Alan Erskine
Post by t***@gmail.com
Serving those who need it most! Anytime Restoration is a family operated
company built on strong principles that makes recovering from a disaster the
least intrusive as possible. We specialize in Storm Damage & Carpet Cleaning
Sterling Heights Michigan.
http://www.anytimerestorationservices.com
Such strong principles that you are posting from Bangledesh?
How do you know that?
Alan Erskine
2012-07-05 11:32:36 UTC
Permalink
Post by William Elliot
Post by Alan Erskine
Post by t***@gmail.com
Serving those who need it most! Anytime Restoration is a family operated
company built on strong principles that makes recovering from a disaster the
least intrusive as possible. We specialize in Storm Damage & Carpet Cleaning
Sterling Heights Michigan.
http://www.anytimerestorationservices.com
Such strong principles that you are posting from Bangledesh?
How do you know that?
I traced the IP - NNTP-Posting-Host: 203.223.94.147

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