"SpaceShipTwo could be single stage to SUBorbit"

On 5/14/2010 11:19 AM, Jeff Findley wrote:
"J. wrote in message
...
On 5/13/2010 3:53 PM, Jeff Findley wrote:
"J. wrote in message
...
On 5/13/2010 1:10 PM, LSMFT wrote:
Robert Clark wrote:
What happened to the X-30?

Clinton.

X-30 was way too much for NASA to do in one huge leap and would have
required billions more dollars just to try to make it work. The state of
the art in hypersonic propulsion still isn't where it would need to be to
build X-30 today (note that X-30 was cancelled more than two decades
ago).
Hypersonic propulsion is one of those promising looking technologies
that's
been "only a few years away" for many decades.

Uh, it's not there because Clinton pulled the plug on it.

NASP was a research playground which was producing little to no flight
hardware, and certainly wasn't producing flying testbeds (i.e. real X-planes
testing real engines on real test flights). Killing a research program
which was sucking up billions of dollars without producing any actual flown
hardware was a prudent move, IMHO.

You have to do the research before you can produce the "flying testbeds".

On 5/14/2010 11:16 AM, Jeff Findley wrote:
"J. wrote in message
...
On 5/14/2010 12:05 AM, Jorge R. Frank wrote:
On 05/13/2010 05:08 PM, J. Clarke wrote:
On 5/13/2010 4:04 PM, Jeff Findley wrote:
"Pat wrote in message
dakotatelephone...
On 5/13/2010 9:10 AM, LSMFT wrote:
What happened to the X-30?

And since when did 50,000 feet become outer space?
I like the part about it using a "liquid chemical propulsion system",
without specifying what those chemicals are exactly.
You could certainly make a ground takeoff rocket plane that could
climb to
50,000 feet, but since numerous types of jet aircraft are capable of
flying to 50,000 feet also, what would be the point of doing this?

The promises made by X-30 were absolutely silly, in retrospect. A
vehicle
which can cruise at hypersonic speeds is going to be very different
than a
vehicle which can accelerate to orbital speeds, yet somehow X-30 was
being
sold as able to do both (makes me think of the SNL skit for Shimmer, a
floor
polish and a dessert topping).

So let's see, a vehicle that can cruise at Mach 20 is going to be
different from one that can accelerate to Mach 25 how, exactly?

If you haven't figured it out on your own, it is not going to be worth
anyone's time to explain it to you. But the quick-and-dirty is that
cruising at Mach 20 with an airbreather is going to require remaining at
an altitude where there is enough O2 to keep the engine going, which
radically increases the total heat load.

Which heat load goes into the fuel and out the exhaust.

Whereas a Mach 25 accelerator
will only spend a brief amount of time in the Mach region where a
scramjet will do any good, so it will need two additional propulsion
systems: one to accelerate to the minimum speed to light the scramjet,
another (necessarily rocket-based) to take over for the final boost to
orbit once the scramjet is useless. The additional weight of having
three propulsion systems more than outweighs the advantages of the
airbreather.

You seem to have missed the point.

IMO scramjets are daft for either mission. It's at times like this that
I really miss Henry Spencer. He could explain this far more eloquently
than I could.

So what do you recommend for Mach 20 cruise if scramjets are "daft" for
it?

That's a little like Peter Pan asking "What would you recommend for human
flight besides fairy dust?".

Neither fairy dust nor runway to Mach 20 hypersonic air breathing engines
exist. The difference between the two is that one is obviously pure fantasy
even to non-engineers where the other is only an obvious fantasy to those
who know enough about engineering to crunch the numbers for themselves and
realize that the math just doesn't work out.

In an apples to apples comparison, rocket engines for orbital launch
vehicles beat even drawing board air breathing launch vehicles for the
reasons which Jorge states.

Math always trumps faith when it comes to engineering.

I see. So your view is that Mach 20 cruise simply cannot be done, it's
eternally impossible and the laws of the universe forbid it.

People like you are pimples on the ass of progress.

On 5/14/2010 11:03 AM, Jeff Findley wrote:
"J. wrote in message
...
On 5/13/2010 4:04 PM, Jeff Findley wrote:
"Pat wrote in message
dakotatelephone...
On 5/13/2010 9:10 AM, LSMFT wrote:
What happened to the X-30?

And since when did 50,000 feet become outer space?
I like the part about it using a "liquid chemical propulsion system",
without specifying what those chemicals are exactly.
You could certainly make a ground takeoff rocket plane that could climb
to
50,000 feet, but since numerous types of jet aircraft are capable of
flying to 50,000 feet also, what would be the point of doing this?

The promises made by X-30 were absolutely silly, in retrospect. A
vehicle
which can cruise at hypersonic speeds is going to be very different than
a
vehicle which can accelerate to orbital speeds, yet somehow X-30 was
being
sold as able to do both (makes me think of the SNL skit for Shimmer, a
floor
polish and a dessert topping).

So let's see, a vehicle that can cruise at Mach 20 is going to be
different from one that can accelerate to Mach 25 how, exactly?

The fact of the matter is that LOX and liquid fueled rocket engines are
really good at accelerating vehicles to orbital velocity.

No, actually they aren't. They can do it, but "really good"? No.

Show me an air breather that can do better.

I didn't say an air breather could do better, I said that chemical
rockets aren't "really good" at getting to orbit.

Better yet, show me an air
breather which can actually fly at Mach 20, which is what NASP was sold as
being able to do.

I'm sorry but I don't get your point here. You seem to be arguing that
if we haven't done something in the past that there's no point in trying
to do it in the future.

Air breathers,
not so much. The machinery required to compress enough air for use in an
engine optimized for rocket like acceleration would be large and heavy.
So
much so that just bringing your own LOX in a tank turns out to be a net
win.

X-30 was intended for Mach 20 cruise. At Mach 20 orbit isn't that far
away.

But you can't get there with air breathing engines. You *must* switch to
engines burning oxidizer carried on board. Now you're talking about two
different sets of engines to maintain.

No, you have no need to do that. None at all. You cruise to Mach 25,
go into a ballistic trajectory, and at apogee you use a small rocket to
perform a circularizing burn.

Either that or you're talking an even *more* complicated engine that can do
both. Considering that we have yet to develop a hypersonic air breathing
engine without a rocket mode, this is a stretch, to say the least.

So you're saying that because the current prototypes work in a
particular way, there's no point in continuing development?

You don't need "rocket like acceleration" if you are cruising at speeds
that high.

And you don't need any "large and heavy machinery" to "compress enough
air".

Scramjets work. Get used to it.

B.S. Scramjets are a research project, not an off the shelf commercial
technology. Anyone who tells you otherwise is selling you snake oil.

Straw man. Atomic bombs are not "an off the shelf commercial
technology" so by your logic they don't work either.

On the other hand, liquid fueled rocket engines suitable for use in orbital
launch vehicles have been available since the late 1950's.

So what?

They are off the
shelf technology today.

So what?

There is no shortage of companies today which will
sell you fully developed liquid fueled rocket engines which are currently
being used on existing launch vehicles.

So what?

If all you guys want to do is just go up and fall back down for the ride
and to get "astronauts wings" and bragging rights you've been in space,
build a fracken rail gun.

Let's see... 50,000 ft =~ 15,000 meters, so your energy per unit mass
would be 150 kJ/kg = v^2/2 = v^2 = sqrt(300 kJ/kg) = 546 m/s

At 2g, acceleration, you'd need to accelerate for 28 seconds, and your
rail gun would need to be =~ 16 km long. Should be do-able. Much of the
cost of real estate could be reduced by making the initial part of the
ride circular.

J. Clarke wrote:

So how many Saturn Vs flew more than a few minutes and how many were
reflown? I guess they don't work either.

You're comparing apples to oranges.

One is a an engine and the other is the vehicle.

The F-1 engine (which would be equivalent to your scramjet) had HOURS of
actual firings before it was flown on a Saturn V. In addition, several were
re-used. Scramjets have neither of this.


But as you seem to know, perhaps you can point me to the ones that
have flown for hours. And the ones that have reflown.

Straw man.

Ummm, hardly. You're the one claiming that scramjets work. I'm asking you
to provide proof.

--
Greg Moore
Ask me about lily, an RPI based CMC.

Fred J. McCall wrote:
"Greg D. Moore \(Strider\)" wrote:

J. Clarke wrote:
On 5/13/2010 11:14 PM, Greg D. Moore (Strider) wrote:
J. Clarke wrote:
X-30 was way too much for NASA to do in one huge leap and would
have required billions more dollars just to try to make it work.
The state of the art in hypersonic propulsion still isn't where
it would need to be to build X-30 today (note that X-30 was
cancelled more than two decades ago). Hypersonic propulsion is
one of those promising looking technologies that's been "only a
few years away" for many decades.

Uh, it's not there because Clinton pulled the plug on it.

Really? Amazing. I didn't realize Clinton whas that powerful.
You mean no one else was capable of doing research on Hypersonic
propulsion?

Nobody is capable of doing any kind of research on anything unless
somebody is willing to put food on their table while they're doing
it.

Hypersonic propulsion was " a few years away" before Clinton and is
still a few years away.

So where would it be if development had been continued instead of
being stopped and restarted again a decade or so later?

Again, it wasn't stopped worldwide. Clinton wasn't that powerful.

Other countries DID do research and development in the meantime.


Oh? Name those programs.

I can think of one in Australia.

I believe the Russians were also still doing some flight research at that
time.



Or are you saying only R&D in the US is applicable?


I think he's saying (and it's hard to argue with) that the US was and
is in the forefront of that research, so us stopping tends to stop
everyone.

Tell that to the Australians.


--
Greg Moore
Ask me about lily, an RPI based CMC.

J. Clarke wrote:
On 5/14/2010 9:10 AM, Greg D. Moore (Strider) wrote:
J. Clarke wrote:
On 5/13/2010 11:14 PM, Greg D. Moore (Strider) wrote:
J. Clarke wrote:
X-30 was way too much for NASA to do in one huge leap and would
have required billions more dollars just to try to make it work.
The state of the art in hypersonic propulsion still isn't where
it would need to be to build X-30 today (note that X-30 was
cancelled more than two decades ago). Hypersonic propulsion is
one of those promising looking technologies that's been "only a
few years away" for many decades.

Uh, it's not there because Clinton pulled the plug on it.

Really? Amazing. I didn't realize Clinton whas that powerful. You
mean no one else was capable of doing research on Hypersonic
propulsion?

Nobody is capable of doing any kind of research on anything unless
somebody is willing to put food on their table while they're doing
it.
Hypersonic propulsion was " a few years away" before Clinton and is
still a few years away.

So where would it be if development had been continued instead of
being stopped and restarted again a decade or so later?

Again, it wasn't stopped worldwide. Clinton wasn't that powerful.

Other countries DID do research and development in the meantime.

So who was putting the same kind of money into it that NASA had been?

Ah, what's that sound? Oh right, the goalposts being moved.



Or are you saying only R&D in the US is applicable?

Who else has the economic resources of the US?

--
Greg Moore
Ask me about lily, an RPI based CMC.

On 5/14/2010 7:19 AM, Jeff Findley wrote:
NASP was a research playground which was producing little to no flight
hardware, and certainly wasn't producing flying testbeds (i.e. real X-planes
testing real engines on real test flights). Killing a research program
which was sucking up billions of dollars without producing any actual flown
hardware was a prudent move, IMHO.

You can't be really sure it didn't produce some form of flight test
hardware, though probably fairly small and unmanned in design.
The program was then (and still is) largely classified in nature due to
the obvious military applications of the technology it would develop:
http://www.fas.org/irp/mystery/nasp.htm

Pat

On 5/14/2010 8:38 PM, Greg D. Moore (Strider) wrote:

I believe the Russians were also still doing some flight research at that
time.

Russians had two test designs
GELA: http://www.aviation.ru/Raduga/Raduga.jpg
Which may or may not have used a true scramjet engine, and the SA-5
boosted test scramjet, which resembled the one they hung under the X-15,
but mounted on the missile's nose:
http://hapb-www.larc.nasa.gov/Public...aa-99-4848.pdf
....and which apparently didn't generate any thrust when ignited.
They are presently working on the Igla scramjet vehicle:
http://www.testpilot.ru/russia/tsiam...ages/igla7.jpg
Although scramjets have very little actual flight time, numerous designs
have been tested in high speed wind tunnels over the past twenty years:
http://www.youtube.com/watch?v=EfJp2luk_IY&NR=1

Pat

On 5/15/2010 12:37 AM, Greg D. Moore (Strider) wrote:
J. Clarke wrote:

So how many Saturn Vs flew more than a few minutes and how many were
reflown? I guess they don't work either.

You're comparing apples to oranges.

One is a an engine and the other is the vehicle.

The F-1 engine (which would be equivalent to your scramjet) had HOURS of
actual firings before it was flown on a Saturn V. In addition, several were
re-used. Scramjets have neither of this.

I see. So the only time that counts is flight hours for scramjets but
test stand hours count for rockets. Can you say "double standard"?

But as you seem to know, perhaps you can point me to the ones that
have flown for hours. And the ones that have reflown.

Straw man.

Ummm, hardly. You're the one claiming that scramjets work. I'm asking you
to provide proof.

If you are not familiar with the testing history perhaps you should not
be pontificating about things you do not understand.