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From: Henry Spencer <>
Subject: Re: What are some "Next Generation" concepts in R&D?
Date: Wed, 13 Mar 1996 23:40:22 GMT

In article <4i1uo7$> writes:
>I'm just curious, but what all projects/programs/concepts are
>currently being SERIOUSLY investigated (by NASA) as a possible STS
>replacement in the future?

Basically, the X-33 project -- a competition to build a demonstrator for
some of the technologies needed for a rocket-powered single-stage-to-orbit
craft -- is it.  Even that is primarily aimed at pioneering technology for
a commercial vehicle, rather than leading into Shuttle II, because there
is no chance whatsoever that Congress will fund a Shuttle II program.

>I've heard of a few vertical
>takeoff/vertical landing testflights and their difficulties, but aside
>from that, what _else_ is being tried?

Not all of the X-33 contenders plan vertical landings, although they are
all planning vertical takeoffs.

Otherwise, nothing else is being tried.  Odd though it might sound, NASA
has spent very little on improving the technology of spaceflight in the
last twenty years.  Goldin says that changing this is a high priority with
him, but so far he's fighting an uphill battle.
Space will not be opened by always                 |       Henry Spencer
leaving it to another generation.   --Bill Gaubatz |

Subject: Re: Gore, Aerospikes, Announcements and Clippers
From: (Robert I. Baumgartner)
Date: Jul 03 1996

In article <>, Henry Spencer
<> wrote:

> In article <4r23kr$>
(WylieC) writes:
> >I've had this picture in the back of my mind of a Clipper taking off
> >not on RL-10s or SSMEs but on aerospikes...
> That was McDD's original design, in fact, later amended to use more
> conventional nozzles due to worries about aerospike aerodynamic behavior
> at low supersonic speeds.  It's still a reasonable idea, if somebody can
> only flight-test an aerospike and eliminate all the paranoid fears.  (This
> is something NASA should have done twenty years ago.)
> -- 
> If we feared danger, mankind would never           |       Henry Spencer
> go to space.                  --Ellison S. Onizuka |

Lockheed Martin is doing just what is needed to validate the aerospike -
they are going to fly a 1/10 th scale model of their lifting body/linear
aerospike design in flight late summer or early fall.  The model with
operating hydrogen/oxygen linear aerospike will be flown on top of a SR-71
aircraft to over mach 3 and 85,000 ft.  Their flight test profile matches
that on an operational SSTO and will validate the aerospike at the same
mach/altitude points that a full scale ssto will fly from sea level to
85,000 ft.  This will cover the crucial transonic/supersonic/low
hypersonic regimes where there is significant aerodynamic/propulsion

Bob Baumgartner

Subject: Re: X-33 VentureStar = Aurora ??
From: (Robert I. Baumgartner)
Date: Jul 17 1996
Newsgroups: alt.conspiracy.area51,,rec.aviation.military

In article <>, (Mary Shafer) wrote:

> On Thu, 04 Jul 1996 05:10:42 GMT, (Michael
Hofmeister) said:
> M> It looks like a close relative of the Martin lifting bodies, which
> M> are the most likely source for the concept to those who do not
> M> believe in imaginary air vehicles.
> Actually, I think it looks more like the HL-10, myself.  I think this
> was built by Bell.  I know Bell built the M2-F2 and M2-F3.  Of course,
> the proposed HL-20 looked a lot like the HL-10, only bigger, so maybe
> the resemblance isn't too startling.
> It certainly doesn't look a lot like the X-24B, which was the only
> conventionally good-looking lifting body, in my opinion.  The X-24A
> looked more like the others, but the X-24B is quite sleek and
> fast-looking.
> --
> Mary Shafer               NASA Dryden Flight Research Center, Edwards, CA
> SR-71 Flying Qualities Lead Engineer     Of course I don't speak for NASA 
>                               DoD #362 KotFR   
> For personal messages, please use

Actually, we tried to incorporate a lot of the X-24A and ACRV lessons
learned in our lifting body RLV concepts studies 1993 - 1994.  We wanted
large lower surface radii for low reentry heating rates.  X-24A had about
a 78 degree sweep.   When you add the requirement to carry enought fuel to
make orbit and the necessity for good volumetric efficiency, the lifting
body RLV had to become stubbier with a leading edge sweep of 70 degrees. 
An RLV (and X-33) has to carry enough main propulsion to take off
vertically (which none of the previous generation lifting bodies needed to
do).  This required a little more fin area to move the aerodynamic center
aft to counteract the effect of all that rocket propulsion weight moving
the cg aft.  That and a lot of wind tunnel testing to date (1200 hours +)
to refine the lifting body contours and optimize control surface
placement/incidence/airfoil sections and you arrive at a X-33/RLV design
which is the optimum neutrally stable across the mach envelope for reentry
and landing (minimum controls to trim and outstanding gust/cross winds
characteristics) and can land at any 8000 ft runway (0.9 CLmax with 40
lb/ft2 planform loading with payload)

Bob Baumgartner
Lockheed Martin Skunk Works RLV program manager

Subject: Re: Rockwell SSTO engine
From: (Robert I. Baumgartner)
Date: Jul 18 1996

In article <4sjfsq$>, (Jason Van
Brecht) wrote:

> Hello to all those who provide me with hours of entertaining reading on this 
> newsgroup.
> Firstly I am glad that Lockheed Martin was chosen to build X-33. Not
> because of there reputation but because they had the better design in
> my opinion.
> My question is since they are using the J2-S (Saturn 5 stage 2&3)
> turbomachinery on the aerospike X-33 engines what are they going to
> use on the full scale engines? (please dont use the SSME's, maby
> Russian engine's)
> What will the performance difference be between the X-33 engines and
> the SSTO's?
> Thanks in advance.

The X-33 Linear Aerospike engine is based on the proven J-2S powerhead. 
It will be sufficient to power the X-33 to its maximum Mach 15+ speed and
to validate the linear aerospike propulsion concept.  This powerplant,
however, does not have sufficient ISP, has a low 1960's vintage chamber
pressure (about 800 psi), has too low a thrust to weight (about 40), and
is not reusable or operable enough for an operational SSTO.  The
VentureStar operational SSTO RLV will have a new design Linear Aerospike
engine built by Rockerdyne and designated the RS-2200.  It will operate at
about 2300 psi chamber pressure (less than SSME's 3000 psi for improved
operability), have about double the thrust and thrust/weight as the X-33
engines (X-33 about 40, SSME about 57, RS-2200 80+), and will have better
ISP than the SSME.  It will be powered by a robust gas generator cycle and
will incorporate two major technology improvements - composite engine ramp
for reduced weight and ceramic turbines for reduced weight and improved
operability (greater temperature margins and imporved life compared to
metal alloys). We will build and test a full scale prototype RS-2200
engine during the X-33 program to validate propulsion performance before
begining design on the operational SSTO.

Bob Baumgartner
RLV Program Manager
Lockheed Skunk Works  (work)  (home)

From: Henry Spencer <>
Subject: Re: Venture Star specs
Date: Thu, 4 Jul 1996 14:04:51 GMT

In article <> (Allen Thomson) writes:
>   Now that LockMart's Venture Star has won the X-33 competition, could
>someone review its major characteristics, such as GLOW, mass to
>various reference orbits, etc?

That's easy:  nobody knows very much about the final proposal, because
LockMart hasn't been talking.  It's a reasonable guess, but only a guess,
that the thing is similar to their earlier AeroBallistic Rocket proposal.
(We know it's the same basic design -- they've said so -- but they may
well have fiddled with the numbers.)

>I seem to recall that when the LM
>proposal first surfaced, it appeared that the vehicle was sized to handle
>NRO monstersats, not unlike the present shuttle.  Is/was that so?

Yes, at least of the ABR.  They thought it was better to build something
big enough to handle the largest payloads, but economical enough that you
could afford to fly it half-empty with a smaller payload.  Mind you, this
is partly the result of politics:  LockMart is firmly focussed on the
short-term government market, which does want big payloads.

>   BTW, is it intended to use X-33 for polar orbits, and, if so, is
>Vandenberg to be used as the launch site? 

X-33 is a suborbital demonstrator that will (probably) never reach any 
kind of orbit.  The choice of test site was part of the contractor proposal,
and I haven't heard what LockMart prefers.  Almost certainly it won't be
Vandenberg, though, because of practical difficulties there.  White Sands,
Edwards, and KSC are the major possibilities.  It might end up being two
of them, because the higher and faster trajectories may not be capable of
returning to the launch point.

For a future orbital vehicle, there is no particular reason to use missile
ranges, once the thing is tested thoroughly.  In fact, there is a particular
reason *not* to use missile ranges:  the oppressive bureaucracy there.  For
early operations, one probably would still prefer a relatively isolated area,
so the early flight path is over sparsely-populated regions.  (Even the
current missile-range operations accept the presence of densely-populated
regions far downrange, on the theory -- successful so far -- that problems 
are likely to happen early.)  The proposed commercial spaceport adjacent to
White Sands would be a good bet.
If we feared danger, mankind would never           |       Henry Spencer
go to space.                  --Ellison S. Onizuka |

Subject: Re: LOX/KERO v LOX/LH2 SSTO
From: Henry Spencer <>
Date: Mon, 30 Jun 1997 17:23:51 GMT

In article <5oq3ue$>,
Stephen Gloor <> wrote:
>There does seem to be a remarkable lack of common sense amongst the
>current space industry.  It seems to be holy writ that H2/O2 is the
>best propellant and anyone who says otherwise is wrong.

Well, apart from the persistence of flawed early analyses, there's also
a historical factor that encourages this belief:  LOX/LH2 has been used
mostly in upper stages, the one place where low *gross* mass is actually
a serious advantage (because it sizes the lower stages).  For an upper
stage, LOX/LH2 remains worth a serious look, although the automatic
rejection of alternatives is still a mistake.

>Many people have published similar findings so why does the X-33 and
>VentureStar still persist with H2/O2.  Do they know something we do
>not know?

No, they're just operating in an institutional environment which penalizes
original thought and rewards going along with accepted wisdom.  Hydrocarbon
fuels are a thing of the past as far as most of those people are concerned,
and LM's X-33 bid was *very* carefully slanted to appeal to the traditional
NASA people (who see it as Shuttle II).

>Maybe they do because I cannot access ANY of the technical
>papers.  I wrote and asked about this and got the reply that I needed
>to be a NASA contractor and something about protecting the technology
>involved in the X-33 from foreign nationals.

It's worse than that -- a fair fraction of the X-33 technology is LM
proprietary and is not available even to US nationals.  (Major parts of
the X-33 *agreement* between NASA and LM are proprietary, in fact!)
Committees do harm merely by existing.             |       Henry Spencer
                           -- Freeman Dyson        |

From: (Henry Spencer)
Subject: Re: Looking for opinions - How long will the shuttle fly?
Date: Mon, 18 Jan 1999 16:45:18 GMT

In article <>,
Greg Moore (Strider) <> wrote:
>> I don't see much doubt that [X-33]
>> will fly, although there are probably more schedule slips coming.  What
>> I'm not sure about is whether it will survive its first flight.
>	I'm not sure what you mean by this.  Do you mean an in flight failure
>resulting in the destruction of the vehicle, or simply the politics and
>economics will kill it?

The planned test program is short enough that it's not likely to get
killed by politics once it starts, and right now the X-33 program seems to
be reasonably solid politically.  No, my doubts are about whether the
first flight is going to end in a crash.  There are a lot of technical
challenges there, and unfortunately, the X-33 design doesn't permit any
reasonable sort of incremental testing (aircraft taxi tests, the DC-X
"bunny hops", etc.) -- many things are going to get a real workout, for
the very first time, on the first flight, and pretty much all of them had
better work.  If some of the rumors I hear are even half-true, that is not
to be taken for granted.
The good old days                   |  Henry Spencer
weren't.                            |      (aka

From: (George Herbert)
Subject: Re: X-33B
Date: 29 Oct 1999 18:58:16 -0700

 <> wrote:
>Huh? This is the first I have heard of the X-33 as a failure, what

It's gotten weight growth to the point that it can no longer
explore the most important part of its flight envelope (around Mach 15)
which was a good deal of the point for making it in the first place.
It will only get around 2/3 the dynamic pressure loads and heat loads
that it was supposed to, and is therefore not a good model for testing
for the eventual VentureStar vehicle.

Comparing with the former Delta Clipper proposal, we had 3 DC vehicles
proposed.  DC-X was a low altitude takeoff, maneuver, landing, and
reusability/maintainability demonstrator.  DC-Y was supposed to expand
the flight envelope into stressing the aerodynamics and aerothermals,
possibly margainally orbital with a DC-Y2 variant, and then Delta Clipper
would be the full orbital version.  X-33 was intended to skip the DC-X
equivalent step and go straight to the DC-Y step.  As is, it's not going
to do well enough at the DC-Y step, and either you build another vehicle
with better performance as a second test step towards full orbital
capability or you take a large risk and don't test out the full
aerothermics until the orbital production vehicle.  It will still do
all the takeoff/landing/configuration sort of tests (like DC-X and DC-XA)
but will only get part of the full dynamic tests.

In that sense, that it was intended to be a single step test vehicle
which would then enable low risk orbital vehicle development, it has
failed.  Either fairly high risk, or another incremental test vehicle
(and another 3? 4? years and ? dollars) are needed to go to Venture Star.
As a programmatic risk/cost/time reducer it has already failed.

-george william herbert

From: (George Herbert)
Subject: Re: X-33B
Date: 30 Oct 1999 00:01:13 -0700

Derek Lyons <> wrote:
> (George Herbert) wrote:
>>In that sense, that it was intended to be a single step test vehicle
>>which would then enable low risk orbital vehicle development, it has
>>failed.  Either fairly high risk, or another incremental test vehicle
>>(and another 3? 4? years and ? dollars) are needed to go to Venture Star.
>>As a programmatic risk/cost/time reducer it has already failed.
>So what have we learned from the failure?  (Which is the point of
>building development vehicles anyhow..)

A few possible lessons below, but keep in mind that we don't
know for sure what we'll have learned from it until it flies.

1. SSTO vehicles may need at least 2 X/Y vehicle steps to the final
SSTO to adequately demonstrate the concept.
2. Tank materials science may not be as advanced as we thought it was.
3. Rocket engine development is hard.  [Oh, we already knew this one... 8-)]


From: "Jeff Greason" <>
Subject: Re: X-33 hydrogen tank fails, flight pushed back
Date: Mon, 8 Nov 1999 10:02:20 -0800

Jens Lerch <> wrote in message
> (Allen Thomson) wrote:
> >  Development of the X-33 rocket plane suffered the latest setback
> >  Wednesday night as a critical component underwent testing at NASA's
> >  Marshall Space Flight Center in Huntsville, Ala. A large section of the
> >  outer wall of one of the vehicle's two liquid hydrogen fuel tanks
> >  separated about two hours after it had completed pressure and structural
> >  tests at the facility, sources said.
> It seems we've come a long way in the last 4 years (NOT):
> A new lightweight composite hydrogen tank for the Delta
> Clipper-Experimental Advanced (DC-XA) vehicle, an unpiloted,
> single-stage rocket being developed by NASA and McDonnell Douglas
> Aerospace, has successfully completed testing at the
> Marshall Space Flight Center, Huntsville, AL.
> "This is really quite a breakthrough," said NASA's DC-XA project manager
> Dan Dumbacher. "This is the largest composite hydrogen tank ever to
> successfully survive flight operating conditions. It demonstrates that
> composite tanks can be used for other reusable launch vehicles in the
> future."
> In the meantime Rotary Rockets and Scaled Composites, two small
> companies located at Mojave airport, have developed and tested carbon
> composite liquid oxygen tanks, but I have no doubt that, given the
> chance, Lockheed Martin will be able to spend a huge amount of money on
> developing composite LOX tanks for the X-33B.

In fairness, there's a *huge* difference between an axisymmetric tank that
you can just wind the fibers on, and a multi-lobed tank of arbitrary shape
such as that LockMart is attempting.  Axisymmetric tanks are MUCH
easier.  So it's not surprising that they're having trouble.

What *is* surprising is that when they proposed the concept, their assurance
that they had it under control and could credibly build the lifting body shape
with good mass fraction was accepted at face value.  I vividly remember
Dave Urie at Space Access many years back pointing out that the
multi-lobed tanks were a critical enabling technology for the LockMart
approach, and that the Skunk Works had the technology to do it in their
back pocket, demonstrated on other programs.

I think the story of the X-33, to a large extent, is the story of how the
Skunk Works "cashed in" on its reputation to win the program, with the
result of demolishing the Skunk Works mystique when they couldn't
deliver.  In the early days, there was a heavy flavor of "trust us, we're
the Skunk Works, and we know what we're doing", and a lot of winking
and smiling suggesting that they had the technology available from black
programs.  I believed more of it at the time than I should have -- swallowing
statements which, from any other source, I'd never have believed.  I don't
think I was alone in that.

Technically, I think the lesson is clear -- stick with axisymmetric tanks.
If they don't fit your vehicle structure, accept that your vehicle is going
to pay the weight penalty to stand off the aerostructure from the tanks.
If you can't accept that weight penalty -- change to a shape that can
use integral axisymmetric tanks.

"Limited funds are a blessing, not         Jeff Greason
a curse.  Nothing encourages creative      President & Eng. Mgr.
thinking in quite the same way." --L. Yau  XCOR Aerospace
   <>                <>

From: mbclapp@aol.comSkipSpam (Mitchell Burnside Clapp)
Subject: Re: X-33 hydrogen tank fails, flight pushed back
Date: 08 Nov 1999 18:42:47 GMT

>Technically, I think the lesson is clear -- stick with axisymmetric tanks.
>If they don't fit your vehicle structure, accept that your vehicle is going
>to pay the weight penalty to stand off the aerostructure from the tanks.

To prove Jeff's point, let's look at some actual numbers.

Ironically, the high-tech metal LO2 tank in X-33 weighs about 5500 pounds,
according to the CDR documentation, and contains about 2300 cubic feet of
oxygen. This is a weight per unit volume of 2.4 pounds per cubic foot. And
that's just the tank! There's still the aerostructure, the attachments, and
everything else that is scabbed on to the tank.

Titan II, stage 1 had a weight per unit volume of 1.6 pounds per cubic foot
before I was born (I'm 36), using integrally stiffened aluminum. Nothing magic
or remarkable was used on Titan, just good conservative engineering. It has
been pointed out here that this stage had SSTO-class performance, with an ideal
delta-V of over 31,300 ft/sec (at a Isp vacuum of 287 seconds, to boot).

Just for reference, the standard weight per unit volume according to the
Executive Branch criteria for a go-no-go decision on SSTO has to be "traceable
to a weight per unit volume of 0.5 pounds per cubic foot." I'm not sure how
they're going to be able to trace the multilobed tank design that far, but
lookin at the problem from this distance, it appears to be a difficult case to

Mitchell Burnside Clapp
Pioneer Rocketplane
"The glass is neither half full nor half empty. It is twice as large as it
needs to be."

From: (Henry Spencer)
Subject: Re: X-33 dead
Date: Tue, 10 Oct 2000 02:14:36 GMT

In article <OSsE5.7333$>,
Jeroen <> wrote:
>> The whole idea of X-33 was to fly something, not to fund another
>> "technology sandbox" which would putter around for a few years and spend a
>> lot of money and leave us no closer to an operational SSTO.
>Then you're right in saying that the choice for the LockMart design was a
>bad one. Do you know what inspired this decision, despite the fact that it
>did not match the requirements of using existing technologies?

By the time the paperwork started being done, the technology-sandbox
people had already got their hooks into it.  And it's clear that they had
way too much say in the bid evaluation -- NASA picked the design that was
pioneering lots of sexy technology, rather than flying something at
minimum risk.

Rockwell took NASA at its word and came up with a very conservative
design.  McDD proposed a DC-X derivative that was at least somewhat
cautious.  LockMart, by the looks of it, accurately concluded that the
noises being made about doing things right were not to be taken seriously,
and that throwing caution to the winds was the way to win.  (This also
ties in with the theory that LM was much more interested in keeping X-33
money away from other companies than in actually flying an X-33 -- added
technical risk then becomes an asset, because it gives you a ready-made
excuse for failure.)
Microsoft shouldn't be broken up.       |  Henry Spencer
It should be shut down.  -- Phil Agre   |      (aka

From: (Henry Spencer)
Subject: Re: X-33/Venturestar Question...
Date: Sat, 18 Nov 2000 23:19:26 GMT

In article <n1wR5.231$>,
Dwayne Allen Day  <> wrote:
>: The tanks were LockMart's idea... and came with a strong hint that they
>: were a simple application of technology already developed for classified
>: projects which couldn't be discussed.
>Most likely out of the classified part of the NASP program...

Actually, it looks like that strong hint was simply a lie, conveyed as a
hint (rather than an explicit statement) to provide plausible deniability.
No, LockMart hadn't built anything quite like them...
When failure is not an option, success  |  Henry Spencer
can get expensive.   -- Peter Stibrany  |      (aka

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