Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_5/V15NO528.TXT

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Date: Thu, 10 Dec 92 05:07:21
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #528
To: Space Digest Readers
Precedence: bulk


Space Digest                Thu, 10 Dec 92       Volume 15 : Issue 528

Today's Topics:
                   absolutely, positively overnight
            AIAA Computing In Aerospace 9 Call for Papers
                               DC info
                         Earth Movie (2 msgs)
                    NSSDC Data on CD-ROM (2 msgs)
                           Orbit Question?
                     Potential uses for the DC-X
         Rush Limbaugh says problems with HST are a DoD hoax!
                         Scuttle replacement
       Terminal Velocity of DCX? (was Re: Shuttle ...) (3 msgs)

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Date: Wed, 9 Dec 1992 16:31:33 GMT
From: "Edward V. Wright" <[e-mail]>
Subject: absolutely, positively overnight
Newsgroups: sci.space

In <[e-mail]> [e-mail] (Josh 'K' Hopkins) writes:

>I know you had a smiley but I want to follow up anyway.  The big problem with
>transoceanic flight is that it would be much to expensive (and besides the
>jet lag would be awful :-).

I believe you have that backwards.  My understanding is, the faster the
flight, the less the jet lag.  As far as expense goes, have you priced
the Concorde recently?

------------------------------

Date: Wed, 9 Dec 1992 16:35:35 GMT
From: Nick Beser <[e-mail]>
Subject: AIAA Computing In Aerospace 9 Call for Papers
Newsgroups: comp.compression,comp.compression.research,sci.astro,sci.space

The following call for papers has just been published in the December
issue of the AIAA Aerospace America, and will be published in the
January 1993 issue of the IEEE Computer Magazine.

Call for Papers:   AIAA Computing in Aerospace 9
                   San Diego, Caifornia - October 19-21, 1993
                   Princess Resort on Mission Bay

Computing in Aerospace is the premier conference for
exchanging technical information, plans, and visions among
the aerospace computing community. Computing in Aerospace
9 is sponsored by the American Institute of Aeronautics and
Astronautics through its Artificial Intelligence, Computer
Systems, Sensor Systems, and Software Systems Technical
Committees, with support from the AIAA Space Based Data
Compression Standards Committee, the Copernicus
Environmental Applications and Methods Group of the Space
and Naval Warfare Systems Command, and the Strategic
Avionics Technology Working Group.

The conference theme is "Advancing the State of the Practice -
Applications and Commercialization of Technology." Paper and
panel sessions will be organized around this theme with six
major areas of interest.  A best paper award will be presented.
The conference will also include a related program of tutorials
and panel discussions conducted by leading aerospace experts.

Location:
The San Diego Princess Resort is located in the center of San
Diego, on a forty-four-acre island in Mission Bay, ten minutes
from San Diego Intercontinental Airport.  Comfortable guest
rooms, spacious conference facilities, excellent restaurants,
recreational and exercise facilities, and a spectacular garden
setting will provide the perfect environment for Computing in
Aerospace 9.  Special conference rates including a government
rate within per diem have been negotiated.

Abstract and Paper Submission:
Prospective authors are invited to submit an abstract of an
original, unclassified paper, not to exceed 1000 words by
February 15, 1993.  Each submission should include complete
addresses and phone numbers of each author.  Also, authors
should indicate which of the topics of interest best describes
their paper.  Notification of acceptance will be mailed to the
primary author by April 16, 1993.   Authors whose work
requires review and clearance by a Government agency are
warned to submit their manuscripts for clearance without
delay.  Final papers are due at AIAA headquarters by August
24, 1993, to be included in the published conference
proceedings.

Panel proposals are also welcome.  They should include a
description of the proposed panel topic or question, not to
exceed 500 words, and a list of participants including a
description of their qualifications.

Submit abstracts and panel proposals by mail, fax, or electronic
mail to:
     Don Rosenthal
     Technical Chair, Computing in Aerospace 9
     2209 Pullman Avenue
     Belmont, CA 94002
     415-592-5421 or 415-604-3367
     415-592-5664 (fax)
     [e-mail]     (e-mail)

Track and Session Topics:
Evolving Aerospace Applications:
Deployment of technology and lessons learned
     Space
     C3I
     Tools, Techniques, and Methodologies
     Technology Insertion Examples
     Training
     Avionics
     Armament
     High Order Languages
     Aerospace Data Compression Case Studies
     Navy and Joint User Data Compression  Applications and Methods

Synergistic Systems:
System-wide integration of multidiscipline computing technology
     Autonomous Systems
     Robotic Systems
     Embedded Data  Systems
     Space Station Freedom, Shuttle, Hubble, EOS, SETI
     ATF, ATA, LHX
     Vehicle Health Management
     Control Centers
     Portable Computing
     Real Time Systems
     Real Time Data Compression Systems
     SCADA

Synergistic Technologies:
The multi-disciplinary aspects of computing
     Data Compression Methods
     Modeling and Simulation
     Signal Processing
     Human-Computer Interface
     Virtual Reality
     Sensor and Data Fusion
     Multispectral Data Compression
     Planning and Scheduling
     Monitoring and Adaptive Control
     Fault Tolerance and Management
     Data Management, Storage, and Reuse
     Supercomputing, Parallel  Processing
     VLSI Design for Data Compression
     Related Technologies for Data Compression

Systems Engineering:
The improvement of productivity throughout the engineering lifecycle
     Development Environments
     Risk Management
     Quality, Reliability, Maintainability,
     Verification and Validation
     Configuration Management
     Design, Development, Integration and Testing
     Productivity and TQM
     Software Management and Metrics
     Life Cycle Costing
     Interoperability and Data Compression  Standards
     Data Compression and Government and Industry  Standards
     Military and Aerospace Data Compression Standards

Theoretical  Foundations:
The emergence of new, revolutionary technology
     Fuzzy Logic
     Formal Methods
     Artificial Intelligence and Neural Networks
     Photonics and Optical Computing
     Speech Synthesis and Recognition
     Advanced Graphics
     Fractals, Holograms
     High Definition Display Systems
     Object-Oriented Systems
     Advanced Parallel Computing
     Advanced Architectures for Data Compression

Aerospace Computing and Society:
The impact of technology spinoff into the commercial marketplace
     Commercialization Issues
     Educational Issues
     Intellectual Property Issues
     Export Control
     Health & Human Services
     Transportation
     Entertainment/Multimedia

------------------------------

Date: Wed, 9 Dec 1992 16:22:36 GMT
From: Henry Spencer <[e-mail]>
Subject: DC info
Newsgroups: sci.space

Here's a summary of some interesting pieces of paper a little bird delivered
to me a while ago, concerning the DC-X/Y program.  [And no, before you ask,
the little bird is not willing to make further deliveries; he's tired enough
after flying all this way.]  [And I really must apologize to him for the
long delay in getting this stuff summarized; it got buried in the Spring
Confusion that also stalled my AW&ST summaries for a long time, and this
stuff only just surfaced again.]  The order is semi-random.

Space transport fundamental needs:  low cost, reliability, responsiveness.
"Time to enter a new era."

Design for Supportability/Operability, performance to follow, operational
costs the crucial factor, subject to development cost/schedule constraints.

Rapid development:  get hardware flying, gain experience, provide for
modular improvements.

DC concepts.  Vertical takeoff, abort from any altitude, manned or unmanned.
One integral vehicle -- nothing falls off.  Completely reusable.  Minimal
pollution with LOX/LH2 propulsion.  "Man capable" -- certified like MD-11
airliner.  Airliner-like operations:  safe abort from multiple engine
failures, rapid turnaround, self-contained flight control, multiple
spaceports.  Two days in orbit, two more days reserve.  >1200nmi cross-range
during reentry.  Landing within 100ft of chosen point.

DC-X fills in database gaps and demonstrates key issues.  The database
for orbital operations and reentry is adequate.  Key points are launch,
landing rotation maneuver, vertical landing (w. ground effects), and
quick turnaround; the database for these is not adequate.

DC-X flight crew (on the ground) of two, plus a ground operations
controller, a software controller, a range interface man, and a program
manager.  Total six, the last three needed only for experimental flight.

DC-X design for operations and support.  Ready access, fast replacement
of failures and damaged parts.  Removable modules and sections.

DC-X schedule.  Vehicle assembled and shipped early Feb 1993 for a static
firing at White Sands, followed by readiness review in early April and
first flight April 23.

DC-X flies autonomously, not piloted from ground.  Ground monitors system
performance, initiates thrust termination and parachute deployment in
case of trouble.

DC-X ground facilities designed for easy operations.  Existing tank
trailers for fuels and gases, above-ground feed lines.  Operations trailer
with RF and fiber-optic communications links for control.

DC-X dry wt 22.2klb, gross liftoff 42.6klb, height 39ft.

DC-X flight tests in three phases.  First, low hover, max 600ft:  control,
landing w ground effect, systems performance.  Second, climb and hover,
max 5000ft with substantial speed:  aerodynamic performance including
power-on drag, expanded performance envelope, launch abort demonstration.
Third, rotation, max 20kft:  up, over, down at an angle, turn base first
and land, for the full DC-Y landing maneuver.

DC-Y orbital prototype.  Fly autumn 1996.  Dry weight (w. margin) 104klb,
gross liftoff wt 1279klb, height 127ft, payload 25klb LEO, 16klb easterly
400km, 10klb polar 400km, cargo bay 15x15x22ft.  Operational DC-1 by 1998.

Crucial technology improvements over shuttle.  Engine performance similar
(not quite as good, but close) without staged combustion.  GOX/GH2 reaction
control system, Al-Li LOX tanks, graphite-epoxy LH2 tank, composite primary
structures, ceramic composite thermal protection.  NASP efforts demonstrate
desired structural weight at greater loads and much higher temperatures.
Structural materials already in use -- composites on ATF fighter prototypes,
existing spacecraft (including Hubble); Al-Li on heavy cargo aircraft.

Proposed DC engine.  LOX/LH2, expander cycle, throttlable, two-position
telescoping nozzle, using mostly-existing experimental turbomachinery.
Existing RL10 becomes RL10-A5 for DC-X, reusable with throttling.
Component work on RL200 starts mid-93, produces RL200-X' (no throttling
and some simplification) for testing in mid-94.  Mid-95, DC-X':  a
reusable suborbital test vehicle, with one RL200-X' and eight RL10-A5s.
[DC-X' seems meant as a replacement for SDIO's sounding-rocket program.]
RL200-Y with throttling and improvements runs early 96, supporting
DC-Y orbital flight tests late in 96 with eight RL200-Ys (four booster
without telescoping nozzle, four sustainer with the nozzle).  Ultimately,
the RL200-1 is committed to production in early 97 for first flights
of DC-1 in late 98.

DC thermal protection:  carbon/silicon-carbide for nose and other hot
spots (maneuvering flaps), multiwall construction with refractory alloys
for most of fuselage, titanium on the lee side and the base.  All
temperatures below NASP and shuttle, well below material limits.

Ample margins to reduce development risk.  Design margins of 15% on dry
weight, 20% on T/W ratio while still preserving ample operational margin.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

------------------------------

Date: 9 Dec 92 15:28:08 GMT
From: Richard Ottolini <[e-mail]>
Subject: Earth Movie
Newsgroups: alt.sci.planetary,sci.space

In article <[e-mail]> [e-mail] (David Toland) writes:
>In article <[e-mail]>, [e-mail]

> (Thomas E. Smith [LORAL]) writes...
>>I have another question that maybe Ron Baalke can answer. Is Galileo going to
>>take any footage of the lunar eclipse tomorrow? I think that would be an awesome
>>short movie, and a once in a lifetime chance.
>
>Too bad it's not a solar eclipse.  Footage of the moon's shadow crossing
>the earth's surface would really be striking!

There are such movies from weather satellite pictures.
Try vmd.cso.uiuc.edu directory wx.

------------------------------

Date: Wed, 9 Dec 1992 14:58:14 GMT
From: "Thomas E. Smith [LORAL]" <gothamcity!tes>
Subject: Earth Movie
Newsgroups: alt.sci.planetary,sci.space

>>I have another question that maybe Ron Baalke can answer. Is Galileo going to
>>take any footage of the lunar eclipse tomorrow? I think that would be an
>>awesome short movie, and a once in a lifetime chance.
>
>What would be the point?  The best seats for that are right here on earth,
>anywhere on the hemisphere from which the eclipse is visible -- no need
>for a billion-dollar space ship or awful false-colored imagery (but
>please don't tell congress all it takes is a $30 pair of binoculars 8-).


**************************************************************************
**************************************************************************
**** Dark side ***********************************************************
*********|****************************************************************
*********|****************************************************************
*********|*********------*************************************************
**********\*****-----       **********************************************
***********\**-----           ********************************************
************\-----          ---*******************************************
************------       -------******************************************
************------     ---------******************************************
************------    ----------******************************************
*************-----   ----------*******************************************
**************-----  ---------\*******************************************
****************---- -------***\******************************************
*******************------*******\*****************************************
**************************** Earth shadow ********************************
**************************************************************************
**************************************************************************
**************************************************************************
**************************************************************************

Ever see an eclipse from this angle? Extra bonus would be if the Earth was in
the same shot. All we have to do is turn the camera, (or spacecraft) a few
degrees and take a shot. And where does the billion-dollar figure come from.
The space craft is already in position as it's happening.

Well, maybe next time.

                            Tom Smith

------------------------------

Date: Wed, 9 Dec 1992 16:21:09 GMT
From: "Edward V. Wright" <[e-mail]>
Subject: NSSDC Data on CD-ROM
Newsgroups: sci.space

In <[e-mail]> [e-mail] (Ryan Korniloff) writes:

>Black and white!? Well, I understand that Voyager's camras took 3 pictures
>to make a complete color image - in a green, then red, then blue (was it
>yellow??) filter.

Actually, it was orange, green, and violet.

Does anyone know the transformations to convert these to R,G,B?

------------------------------

Date: Wed, 9 Dec 1992 16:24:47 GMT
From: "Edward V. Wright" <[e-mail]>
Subject: NSSDC Data on CD-ROM
Newsgroups: sci.space

In <[e-mail]> [e-mail] (Ron Baalke) writes:

>Third, you have to adjust for the orange filter (Voyager didn't
>have a red filter).  The only software I know of that does all of this
>is VICAR, which was developed by the Image Processing Lab at JPL.

If you want accurate color, you also need to adjust for the violet
filter.  (Violet's not the same as blue.)

If you want really *really* accurate color, you'll even need to
adjust the red channel.  (The red that's transmitted by Voyager's
filter is probably not the same red that's emitted by your monitor's
phosphors.)

------------------------------

Date: Wed, 9 Dec 1992 14:04:23 GMT
From: Alan Carter <[e-mail]>
Subject: Orbit Question?
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Philip Young) writes:
|> In article <[e-mail]>, [e-mail] writes:
|> |> Your polar geosyncronous satellite takes out one equatorial geosynchronous
|> |> satellite every 24 hours as it passes over the equator at 24,000 miles
|> |> altitude.....
|>
|> If you have enough muscle to counteract the rebound, you should be able
|> to  collect one every 12 hours (probability proportional to satellite
|> density in GEO).

Er... Won't it just take out a *maximum* of 2, and in future fly through
the holes it's made?

   Alan

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~"They're unfriendly, which is fortunate, really. They'd be difficult to like."

   Kerr Avon
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

------------------------------

Date: Wed, 9 Dec 1992 14:16:11 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Potential uses for the DC-X
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Pat) writes:
>So we are spending the money to build the DC-X and flight test it.
>are there any useful science missions it could conduct while up there?
>I would guess that while jets and balloons can fly higher and stay longer,
>only helicopters can conduct precision hovering, and they stay below
>10,000 feet.
>Would there be an air sampling or astronomical observations that would
>want to hover around at 30,000 feet?
>I am certain i could conduct some great photographs,  but would
>the DC-X be useful for like aerial photometry,  or resource mapping?
>the U-2 has turned out to have some great research potential, maybe the
>DC-X or Y could also.

The U-2 was designed to loiter for long periods at high altitudes
while acting as a photo platform (spying) and atmosphere sampler (fallout).
DC-X won't be able to hover long, VTOL eats fuel at a prodigous rate,
and the exhaust from a hovering DC-X would obscure photography and
contaminate air sampling. At only 30,000 feet, it's not even a good
platform for cosmic ray studies. It's a flight test article, let it
do that to destruction and it will have served well.

Gary

------------------------------

Date: Wed, 9 Dec 1992 16:17:20 GMT
From: JIM GRAHAM <[e-mail]>
Subject: Rush Limbaugh says problems with HST are a DoD hoax!
Newsgroups: sci.space

In article <roelle.723835713@uars_mag>, roelle@uars_mag.jhuapl.edu (Curtis Roelle) writes...
>[e-mail] (Robert Dyess) writes:
>
>>The interesting phenomenon has been the way in which so many intelligent
>>people can be brought to a boil over a message posted by one person who
>>made an error. I've been reading this Newsgroup daily and as far as I can
>>tell, all of the heated discussion about how stupid Rush is can be traced
>>back to Ryan's message quoted above. Incredible isn't it. :-)
>
>Just think how often the press takes a snippet quote from a scientific
>figure and starts a feeding frenzy (When is it that S-T will extinct
>earth?).  How is this situation different?  Isn't this just the same
>outrageous occurrance in reverse?  Limbaugh, a figure from the press
>says something and someone from sci.space hears a few words listening
>to his car radio during his lunch hour.  Next it gets posted out of
>context starting a rabid cascade by people who admit having never
>heard the program!  How embarassing.

What's also interesting is how a few of the followup posters have been
"apologetic" about listening to Rush's show.

Not only that, it never ceases to amaze me how the liberal crowd
constantly preaches against intolerance, yet they have no problem
whatsoever with being intolerant of those with viewpoints that
oppose theirs.

Heck, I'm not even a right-wing conservative (nor am I a liberal), and
I can still see through the hypocrisy.

Jim Graham

        -> ->Disclaimer: I do not speak for my company. <- <-
                          Neither do they speak for me.
 ______________________________________________________________________
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------------------------------

Date: Wed, 9 Dec 1992 15:12:40 GMT
From: Greg Moore <[e-mail]>
Subject: Scuttle replacement
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
>   I hate to point this out, but none of those programs were ever
>planned for NASA funding.
>   DC-X -- SDIO funding (DoD)

    No, but DC-Y may be, and Goldin says he will use DC-1 if it proves its
worth.

>   Laser Launchers -- what little funding is being spent comes from
>        LANL, and LLNL, both DoE labs, with a large component of
>        SDIO funding.  Not NASA funded.

    This may come as a big surprise to Leik Myrabo here at RPI...
as I recall, NASA signs his checks.

> -------------------------------------------------------------------
> Wales Larrison                            Space Technology Investor
>
>--- Maximus 2.00

------------------------------

Date: Wed, 9 Dec 1992 15:44:20 GMT
From: Paul Dietz <[e-mail]>
Subject: Terminal Velocity of DCX? (was Re: Shuttle ...)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Aaron Sawdey) writes:

> Actually, the difference in mass is significant. A formula 1 engine
> would fit into the engine bay of my Honda CRX -- I think they're
> usually about 1.5 liters displacement with LOTS of turbocharging --
> (I can't guess what it'd be like to drive it with 750hp under the hood ;-)
> while a 750hp truck engine would be as big as the entire passenger
> compartment (guess: 8-12 liter turbodiesel?). Same power means similar
> amounts of waste heat (probably the F1 engine is less efficient, so it'd
> more waste heat to get rid of). Much smaller size of the F1 engine means
> the heat is much more concentrated -- and probably less evenly distributed.
> This applies to two rocket engines of different sizes and similar thrust
> as well.

Actually, rocket engines are considerably *more* efficient that the
engine in your Honda CRX (if by efficiency of a rocket you mean the
fraction of chemical energy in the fuel converted to kinetic energy of
the exhaust).  Moreover, in regeneratively cooled engines, almost all
the heat that conducts into the rocket structure is recycled right
back into the propellant.  This heat flow typically is small compared
to the power output of the engine anyway (it has to be, else the
rocket would melt almost instantly); the inefficiency of a rocket
comes mostly from the fact that the exhaust still contains
considerable thermal and chemical energy after it leaves the nozzle.

    Paul F. Dietz
    [e-mail]

------------------------------

Date: Wed, 9 Dec 1992 14:04:55 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Terminal Velocity of DCX? (was Re: Shuttle ...)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Pat) writes:
>
>Yeah, but with the shuttle, it was kinda bullshit from the start.
>A truck does not have to be rebuilt everytime it returns to base.
>Certainly, shuttle was a different approach from expendables, but it
>really was a poor design approach.  i think it was too ambitious
>for technology,  and starved for cash.  i think had they spent some
>more money up front and built the STS properly, we wouldn't have the problems
>it has.

No argument here. Shuttle is far from optimally designed. It's one
critical advantage over every other system is that it's *flying*.
Titan IV is turning into a bigger hanger queen than Shuttle ever
was, DC-1 is a paper airplane, etc. A more intelligently designed
spacecraft is badly needed to replace Shuttle, but the DC program
isn't it. It may be *part* of a fleet of specialized vehicles that
replace Shuttle, but it can't do many of the things that Shuttle
is capable of doing, lifting large payloads, carrying large crews,
support Canadarm, return large objects, etc. Shuttle's problems are
threefold. First it was designed to be all things to all people,
a difficult task. Second, it was cash starved at the time the SRB
decision was made, the flyback liquid booster was a much better
idea that ran afoul of development funding limits even though it
would reduce operational costs and enhance reliability and flight
safety. And third, again because of developmental funding problems,
it became hostage to DOD flight requirements in excess of original
Shuttle requirements. This imposed higher stresses on SSME than
had originally been planned.

>DC-Y may have a narrow mass margin, but i'll still consider it a success
>if it makes a working ballistic shot.  I am sure to pull of a decent
>SSRT, yoou will need some better engines or higer performance
>structural members or maybe even some solid boosters, but that
>to me the real point of DC-Y is not to go to orbit and back with
>cargo,  but to even make it up there and back.
>
>If you can show the approach to be right,  from their it can be improved.

Getting to orbit without any payload doesn't demonstrate the approach
is right. Demonstrating the approach is right requires showing that the
system can deliver payload to orbit at a lower cost per pound while
maintaining higher reliability and availability than competing systems.
Compare SSTO to Proton, the payload capacities are similar. SSTO has
to beat Proton costs and reliability to be a success. $300 a pound
is a difficult target. Of course CIS prices are likely to increase
once the fire sale is over.

>And i am sure everyone expects the DC-1 one to be many years off.
>I guess you feel the X-15 was a useless waste of time.  what kind of
>spacecraft needs a mother ship, only hits 150,000 ft, wont beat Mach 7
>and costs 200,000/flight.  DC-X will prove the flight profile of the DC-Y,1
>and hopefully demonstrate high reliability, fast turnaround...
>Besides the DC-X may actually have some uses.

I support the DC-X tests. The data developed may be useful in later
vehicles and the cost is not excessive. Like the X-15, however, I
doubt it's design will scale to commercial products. How many airliners
are derived from the X-15? The SR71 is the only manned vehicle that vaguely
resembles the X-15 and it's flight systems are entirely different. And
it's being retired as not cost effective for it's mission. Pegasus is
the other possible derivative of X-15, and it has the *highest* cost
per pound of any flying system, and, so far, a poor reliability record
with only a 50% success rate. X plane data has been incorporated into
several high performance system designs, but they don't look or work
like the X plane at all. I don't expect any DC-1 to look like a scaled
up DC-X either.

Gary

------------------------------

Date: Wed, 9 Dec 1992 15:11:57 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Terminal Velocity of DCX? (was Re: Shuttle ...)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Edward V. Wright) writes:
>In <[e-mail]> [e-mail] (Gary Coffman) writes:
>
>>The proposed DC *is* a rocket, it *is* a low margin system as any
>>SSTO has to be, and it has exactly *zero* flight history. It will
>>use throttleable engines with variable geometry *based* somewhat
>>on RL-10 technology at first, but radically new and never flight
>>tested.
>
>The engines used by every commercial airliner were "radically new"
>and "never flight tested" at one time also.  Despite your claims
>of "radicalism," the rocket engines are little different from those
>we have been building for more than 40 years.  They are a new design,
>not a new technology.

Yes, they are basically a *new* design despite being based on the
proven RL-10. Adding throttleability to a rocket engine isn't simply
a matter of adding a valve. Standing pressure waves in the engine
change under different thrust settings, often in unpredictable ways.
You have to test and test to determine that all regions of throttle
action result in a stable burn with temperatures and pressures in
various parts of the combustion chamber remaining within safe limits.
This isn't trivial engineering that can be brushed aside by saying
it's been done before with other engine designs. The variable geometry
expander has never been tried on an operating rocket engine before
either. It *should* work, but they won't know until they try it what
problems may develop.


>Now, please, calm down before the environmentalists attack you for
>depleting the world's nonrenewable supply of asterisks.

My keyboard has an unlimited supply. They're biodegradeable too. :-)

>>Later it intends to use aerospike engine designs that have
>>*never* been tested, even on the ground.
>
>Really?  On what do you base this statement?  The designers
>at McDAC have repeatedly stated that they do not plan to use
>an aerospike.

The aerospike is the alternative design if the variable expander
doesn't work out.

>>It will be difficult for it to live up to rocket standards of
>>reliability, much less airliner standards of reliability.
>
>The difficult we do right away.  The impossible takes a little
>longer.

Cute.

>>This is radically new engine and control technology being pioneered
>>on a very marginal flight article.
>
>Saying that doesn't make it so.  The engine is about as "radically
>new" as a new microprocessor.  The control problem is the same one
>that was solved, for ICBMs, in the 1960's.

That's funny, I didn't know ICBMs did controlled powered landings. I
thought they used ballistic re-entry vehicles atop a multistage suborbital
rocket.

>>The cost and reliability levels being bandied about have no basis other
>>than wishful thinking.
>
>Sure they do.  It's called "math."

"Math" says 2+2=4, it says nothing about the appropriateness of 2.

Gary

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End of Space Digest Volume 15 : Issue 528
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