Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_5/V15NO560.TXT

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Date: Thu, 17 Dec 92 05:08:06
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #560
To: Space Digest Readers
Precedence: bulk


Space Digest                Thu, 17 Dec 92       Volume 15 : Issue 560

Today's Topics:
                      : Relay to Follow Galileo?
                   absolutely, positively overnight
                      DC vs Shuttle capabilities
                    Does Sun have magnetic poles?
                     fast-track failures (2 msgs)
          Greek jet engine (Was: Terminal Velocity of DCX?)
Private Phisical Inst. seeks collaboration in different forms and directions
       Shuttle alternatives (was Re: Terminal Velocity of DCX?)
                           SSTO vs. 2 stage
       Terminal Velocity of DCX? (was Re: Shuttle ...) (4 msgs)
                   what the little bird told Henry

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

Date: 16 Dec 92 21:41:58 GMT
From: David Seal <[e-mail]>
Subject: : Relay to Follow Galileo?
Newsgroups: sci.space

In sci.space it is written:

>>But we're talking about a multi-Billion dollar program here. I just
>>wouldn't want to take that risk. That is a lot of money the throw away
>>because the "stupid" antanna won't open.. And this will further make the
>>image of NASA tarnish even more. Yet another American blunder.. we don't
>>need it. How are we going to argue that we need to go to this planet and
>>that planet if we can't build the hardware to do the job???
>>
>>
>>        -- Ryan Korniloff
>>        -- [e-mail]

>The folding, umbrella-type antennae have been used at least ten times
>in space (that is, two each on TDRS-A, TDRS-C, TDRS-D, and TDRS-E, one
>on ATS-6 (late-70s pathfinder comsat) and one on Galileo.
>
>Only the one on Galileo failed to open on command, and there is still
>hope it will be coaxed open. (They haven't tried brute force yet.)
>Lesson:  OPEN THE DAMNED ANTENNA IMMEDIATELY AFTER LAUNCH!!!
>-Brian

Let me add a brief spout:

It is always easy after a failure (with 20-20 hindsight) to say 'jeez,
how stupid.  why the heck couldn't you just have done X instead?'
from my POV, there are a billion things that can go wrong that can
royally
screw up a mission, and you try to avoid the major ones, and the ones
you can eliminate easily (i.e. w/o $$ or complexity or exhaustive analysis).
I think the view of space mistakes can be somewhat overblown because a lot
of people (not necessarily Ryan, just in general) don't really understand
how difficult it is to do what we do.  The HGA looked like a good choice.
It had performed well in a space environment previously.  And the test
program was supportive.  But it happened anyway.  It may look easy to you
with hindsight, but don't think for a second that the project staff of
Galileo is kicking themselves because they picked a 'stupid' design.

also:  the next attempt is the dec. 28 ballscrew hammering.  it is not
what i would call 'coaxing.'  from now on, it is brute force that will
be used.  I've heard they might even yield the pins or the antenna ribs
during the hammering.  (this, of course, would be fine.  any portion of
the fully deployed HGA bigger than a paper plate would probably provide
better performance than the LGA).

also:  from what i know, opening the antenna immediately after launch would
probably have had the same result.  the problem was that the lubrication
in the pin mountings had worn away during transport and/or launch.  i think.

regards,
ds

standard disclaimers and all that.
--
-----------------------------------------------------------------------------
David Seal                 |  Jet Propulsion Laboratory  |     sunset: 7:54pm
[e-mail] |       Mission Design        |   temp: 82 degrees

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

Date: 16 Dec 1992 21:54:34 GMT
From: Pat <[e-mail]>
Subject: absolutely, positively overnight
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Edward V. Wright) writes:
>
>"Air Force One" is just a call sign for whatever plane the President
>happens to be riding in.  The Air Force has an entire squadron of planes
>which, at one time or another, may be Air Force One.  The big 707 (now
>747) is the most famous, but not every trip requires something that
>large.
>


Well, when he is being flown around in his Sikorsky to andrews and the white
house,   then he is in ?Marine One".  I know the army has a small
helicopter detachment to fly him around and i bet then it's "Army One".

So if the Navy buys the first executive DC, then it will be Navy One that
goes globe-trotting.

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

Date: 17 Dec 92 03:14:06 GMT
From: Greg Moore <[e-mail]>
Subject: DC vs Shuttle capabilities
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:
>In article <[e-mail]> [e-mail] (Greg Moore) writes:
>
>First of all, which crew? The flight crew rides in the cockpit which is
>above the cargo bay. If more crew are needed, then the satellite can
>ride in the part of the cargo bay not used by the extra crew.
>
    Sorry, my mistake, I got confused on the crew accomodations of the
proposed DC-1.

    Another question though:  Am I correct in recalling that the goal is
to use pilots, and not astronauts (at least in the NASA sense) to fly the
proposed DC-1?  Who will do satellite repair? Who pays for training? The
customer, or will McD (or whoever operates it) have "on-call techs" that
you can pay extra for.  (I'm not calling for you to predict the future
(thouh seem to believe at times you know it... :-) just an idea if SDIO
has given this any thought?

>If it turns out that this isn't roomy enough, then you use the technology
>developed under DC to build a larger vehicle. After all, DC will be a usefull
>piece of technology but it isn't the only spaceship which will ever be built.
>

    But wait, DC-1 was going to solve all my problem, and slice my bread.
Seriously though, I think this leads to a comment directed to you, Gary,
Michael, and Edward and any others I've forgotten.
    We've all argued various merits, benefits and drawbacks of the DC
program, but sometimes I think we forget what we are talking about.  Are
we talking about DC-X, the planned DC-Y, or the proposed DC-1.  It seems
to me that everyone here agrees that DC-X is a good idea, whether or not it
works.  As long as it is treated like an X program, it seems to get a lot
of support.  We will learn from it.  Perhaps we will find everything
will be as "easy" as they say, or perhaps they run into stumbling blocks.
But we won't nkow until we try.
    DC-Y doesn't seem to be of much conflict per se.

    I think we differ big-time when it comes to DC-1.  Allen seems
to me to be saying, "Things will work out, and this is how it will be."
I think that is the attitude that bothers me the most.  That is the
exact same thign that was said with the Shuttle.  NOw granted, there are
some major difference, major enough to make me believe that DC-1 has
a better chance than the Shuttle did.  However, we can't be sure
until we start FLYING these things.  A better way of thinking may be,
"If things work out, this is how it will be."
    I don't mean to pick out you Allen, and I don't mean to pick
on your belief in the DC-X program, but sometimes it seems to me you're
trying to sell it before it's tested.

Off the soapbox.

>>    I eliminated some stuff above, but wanted to add some stuff here.
>>Actually, plummeting launch costs may contribute to lower payload costs
>>since people will be willing to build a less fault tolerant system
>>knowing that if it fails, they can launch another cheaply.
>
>Exactly.
>
    Ah, we agree.  That's nice to hear. :-)

>>As for on-site repair, for now DC-? fails for the same reason that
>>the Shuttle normally does, it can't get up to GEO, you need a  OTV...
>
>Although a DC with a robot arm and some avionics changes may be the
>OTV. Certainly the engines for a DC will be just what an OTV needs.
>
    Is this inherent in the RL-10 design, or does work need to
be done on the tanks to make sure the fuel is near the outlets?

>>>>    Also, as for retrieval, the Shuttle has shown that it ain't
>>>>easy to do.  Will a two day on-orbit time be enough?
>
>>>It may take modifications to the DC. At the very least you need to add
>>>a robot arm and an airlock.
>
>>    Granted, but that's not what I meant.  Will you have enough time
>>to rendevous and capture the satelite?  It took what 3 days for the
>>shuttle to capture Intelsat VI? That's aday more than DC-?.
>
>Load the pallet with some extra power sources, add some solar cells and
>your all set.
>
    So, your pallet now has attachments for consumables that DC-1 can
draw on?  (Hmm... let's just use a EDO... Oops, no, ITWIH Syndrome. :-)
(Seriously, I know, it probably won't fit.)

>>Also, what type of fuel margin would DC-1 have for IN-orbit
>>manevours?
>
>DC-Y has a fair amount of fuel for on orbit delta V but I don't
>remember the exact numbers. How much DC has will depend on the
>design requirements and who pays the bills.
>
>But note that on a DC-Y you can power the fuel cells, main engines, and
>RCS from the same source. This allows you some very powerful tradeoffs.
>
    True, but I'd still like to have a separate fuel reserve or
power supply.

>>(I realize it has enough for landing, and of course
>>you don't wnt to cut into that for safety reasons.)
>
>At least enough to get back to the orbital fuel dump.
>
    Oh, gee, I didn't realize we had one.  And what if it isn't
in your orbital plane?  Might was well re-enter...

>>    Use it yes, but use it for what it can be used for economically.
>>Let's see, we've added an airlock, an arm, additional on-orbit capacity.
>>Hmm, that adds up, and add complexity.  Yes, let's ok at possibilities,
>>but not claim t they are definites.
>
>Agreed. But they don't look all that hard given a working DC.
>
    And they didn't look all that hard given a working shuttle.
Hmm, RMS came from Canada, and even at that was a bargin.  So I'm sure
DC can use one.
    Airlock, that's simple enough.
    On-orbit capacity: That's a little tougher.  Depends on how
your DC is scarred, etc.  BTW, what is the FAA say about adding fuel tanks.
I know the 747-400 didn't have to be completely recertified... I'm sure
DIC won't have to be either, but I'm sure there would have to be some
testing.

    Sounds good.  Prove to me it works with flying hardware, and
I'm sold.

>>    Also, does it make sense for the DC1-EOT and OMV and LM the same.
>
>Not 100% the same. For an OMV I would strip off the thermal protection
>system, add attach points outside for additional fuel and hardware (like
>arms), I might look at lining it with solar cells for more power. For a LM
>I think you would need to provide better insulation to reduce fuel boil off,
>replace the landing gear to give it a larger footprint (like the Apollo LM),
>and beef up the TPS for aerobreaking.
>

    Beef up the TPS how much?  Also, I believe that Henry pointed out
that it ieasier to do a direct re-entry than a return to orbit.  (I can't
recall why, and wasn't celar at the time I read it, so I may be wrong.)
If so, will you have enough fuel to do this.  Remember, until you have your
moonbase set up, you've got to leave LEO, land on the moon, take off, and
either re-enter, or re-enter LEO.
    Now your changing your landing gear.  How, what does this entail?

>This will allow us to use the same core vehicle for multiple applications
>which will allow development to be amortized over more vehicles and reduce
>construction costs since we are building more core vehicles.
>
    Ayup, and if we had built Shuttle-C, we could have amortized
engine costs a tad more, and amortized facility costs more.

>      Allen
>
>--
>+---------------------------------------------------------------------------+
>| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
>|  [e-mail]     |  nothing undone"                                       |
>+----------------------131 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: 16 Dec 92 21:47:06 GMT
From: Stephen Tell <[e-mail]>
Subject: Does Sun have magnetic poles?
Newsgroups: sci.physics,sci.electronics,sci.space

In article <[e-mail]> [e-mail] (Babak Sehari) writes:
>Recently, an attempt has been made to create electricity using a large
>electric loop in the space using earth magnetic force.  However, such thing
>should not be a source of energy in the space since it takes energy to
>change the flux that passes through wire loop and only a fraction of that
>energy would be translated to electric energy. Further more, if the rotation
>of satellite itself to be used for this task, the emf back force would change
>the speed of the satellite.  That results in altitude drop for satellite.

If I may be allowed to suggest in a serious forum an idea I first saw in a
piece of fiction, from David Brin's short story, "Tank Farm Dynamo" (found
in the Brin anthology "The River of Time" and perhaps elsewhere):

Generate your electricity using photovoltaics or somthing else, and use the
large loop in the Earth's field as a motor, not a generator.  This boosts
your altitude.  The satelite in the story was an orbiting tether with an
elevator running up the cables.  Payloads would be carried up and down, with
more net mass going up than down, which over time would lower the altitude
of the satelite by significant ammounts.  Use of the magnetic effect
countered this tendancy.

>                            Babak   Sehari.



--
Steve Tell       [e-mail] H: 919 968 1792  | #5L Estes Park apts
UNC Chapel Hill Computer Science W: 919 962 1845  | Carrboro NC 27510
Engineering is a _lot_ like art:  Some circuits are like lyric poems, some
are like army manuals, and some are like The Hitchhiker's Guide to the Galaxy..

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

Date: Wed, 16 Dec 1992 18:48:07 GMT
From: "Edward V. Wright" <[e-mail]>
Subject: fast-track failures
Newsgroups: sci.space

In <[e-mail]> [e-mail] (Gary Coffman) writes:

>Yeah, bad line of argument, most of the systems that made it as far
>as being assigned a number weren't technical failures even if they
>were market failures. Actually I was thinking of the P-39 when I
>wrote that. That aircraft made it into production, but was a dismal
>failure... This was an example of
>fast tracking from a prototype to production without working out
>all the bugs required to make it a practical fighter.

And how long did it take before the P-39 was succeeded by a fast-track
replacement? And how many generations of fighters did the US go through
in the next 15 years (the time it takes to develop one fighter today)?


There's a moral here.  Do it fast, do it quick, do it cheap.  Take
risks and being willing to *accept* an occassional failure.  If a
project does fail, forget the finger pointing, the blame casting,
and the Congressional investigations, just get on with the next one.
Don't put all your eggs in one basket.  And staff your projects with
competent people motivated by *success*, not failure-oriented "engineers"
who spend all their time generating cover-your-butt paperwork.

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

Date: 16 Dec 1992 22:33:51 GMT
From: Pat <[e-mail]>
Subject: fast-track failures
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>>
>>Just which aircraft were you thinking of, Gary?  I can think of one
>>aircraft that had a bad performance shortfall but was redesigned and
>>continued into a successful program (the F-102).  I can't think of
>>*any* F-series "gap" in the last 40 years that fits your description.
>
>were market failures. Actually I was thinking of the P-39 when I

(Stuff deleted)


Actually another case was the YB-49  and YB-50?  those were
northrops  flying wing prototypes,  the turbo-prop  and the jet versions.

They actually flew but had trouble with range,  and power.  the prop job
needed twin counter rotating props to really develope thrust.

Plus there were enormous political problems witht he Air Force on the
birds.  Too bad,  the effort broke jack northrop  and he never got to
see his vision carried off in the B-2.

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

Date: Wed, 16 Dec 1992 19:22:57 GMT
From: GRASSO CHRISTOPHER A <[e-mail]>
Subject: Greek jet engine (Was: Terminal Velocity of DCX?)
Newsgroups: sci.space

In article 26326, (Edward V. Wright) writes:

>I think the ancient Greeks, who built a working jet engine,
>lived a little more than 50 years ago.

Interesting. Would you care to elaborate?

    -Chris Grasso
     CU Boulder

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

Date: Wed, 16 Dec 92 19:21:38 +0300
From: "Aleksandr V. Kats" <[e-mail]>
Subject: Private Phisical Inst. seeks collaboration in different forms and directions
Newsgroups: sci.space

                           Dear Sir,
            Works of  private little venture Eco-Energy Institute are
       directed in general for ecology clean  possibility  of  energy
       production, conservation and utilisation.
            We are interested in collaboration,  the orders  of  some
       criogenic devices and osonators, and joint investigations.
            Suppose, that it is reasonable to  have  the  discussions
       and   meetings   with   investigators,  working  in  following
       directions:
       1. NASA  programs  of  metastable  helium  states (MHS)  as a
       rocket propellant   and   of   moon   He3   utilisation,   MHS
       manufacturing, conservation and utilisation.
       2. Weakly  bound  species: helides, rare  gas - hydrogen - and
       carbohydryde clusters, now wellknown foullerens,for example,
       - the manufacturing of its.
       3. Ozone generation, conservation and utilization.
          All theese ones may be used as energy accumulated species,
       but not only, ofcourse .
       4. The plasmoreactor methods of hydrogen from water and H2S
       production.
       5. Scintilators for nuclear and cosmic radiation detecting -
       some unusual methods of manufacturing, examination and testing.
       6. Mathematical modelling of dust ewolution and grouing in air
       on the base of Smoluhovsky  equations.
          We are interested to take part in the experimental work on
       the base of US organisations in all this fields.
          In all this directions  we have ideas,  know-hows,  skill,
       experience, patents.
          Now the negotiations, concerning 4 and 5 items, with some
       US Universities are in progress.

          We would like to have grants and other forms of collaboration
       for our researchers, working in this directions.


                S.Y.
                D. Myshkis,
                Director of Eco-Energy Institute
                Ph.D, Mb.of RAN Commitee for
                Energy Accumulating Species  Using

                Ukraine, 310103, Kharkow,
                ul.Kosmonavtov,5A/77.
                tel.[phone]
                fax [phone]

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

Date: Wed, 16 Dec 1992 22:25:00 GMT
From: "Michael V. Kent" <[e-mail]>
Subject: Shuttle alternatives (was Re: Terminal Velocity of DCX?)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:

>That is my point.

Your point is a moving target, but I'll do my best to adress its major
aspects.

Point 1:  In the beginning of this mini-thread, Allen stated that for the
cost of one Shuttle flight, NASA could develop DC-X and launch whatever was
to go up on the Shuttle on a Titan IV.

This is not true primarily because Titan IV cannot carry most Shuttle pay-
loads.

1) Titan IV cannot carry the payload of the Shuttle.  Titan IV's payload is
only 38,500 lbs to a 100 nmi orbit, while Discovery and Atlantis can loft
52,000 lbs to a 150 nmi orbit.  Endeavour can launch a few thousand lbs more.
While I don't have the equations on hand, raising Titan IV's standard orbit
to 150 nmi would cause its payload to drop to about 30,000 lbs, barely half
that of Endeavour.

2) Shuttle is the only manned spacecraft we have.  An astronaut will not sur-
vive long in a Titan IV payload fairing, as the fairing has no life support
system.  This is important for the middeck payloads, Spacelab, and Spacehab.
It is also important for satellite servicing missions where astronaut pres-
ence is required for primary (Intelsat, Hubble servicing) or contingency
(Hubble, Compton deploy) purposes.

3) Titan IV has no return capability.  This is important for all astronaut
operations, and is required for satellite retrieval missions.  It is also
required for SPAS, USMP, and many GAS and middeck payloads where either
samples need to be returned for study or the entire system needs to be re-
turned for refurbishment.

4) Much Space Tranportation System hardware requires the Shuttle explicitly,
or one of the above attributes.  Spacelab and Spacehab, for example, require
the Shuttle for life support, power, and heat rejection.  Other hardware
elements requiring the Shuttle are the Spacelab pallets, the RMS, and
most middeck payloads.

5) The Titan IV's launch rate is very low.  It has flown six times since its
1989 debut, while the Shuttle has flown over 20.  All available Titan IVs
for the near future will be used for launching Air Force payloads.  None are
available for NASA or commercial uses for quite some time.

Conclusion: Whether or not the cost of a Titan IV launch plus the cost of
DC-X is less than the cost of a Shuttle flight, the point is moot, since
nearly all Shuttle payloads require some aspect of the Shuttle that is unique
to the Shuttle.  For these five reasons, a Titan IV flight can not substitute
for a Shuttle flight.

Point 2: STS-52 could have flown on a $10 million Pegasus.

I have addressed this in another post, so I will just post the conclusion
here.

Conclusion:  Point 2 is simply not true.

Point 3:

>For what we have spent on Shuttle we could have built two Freedom
>space stations or about 20 or so Industrial Space Facilities. Utilization
>of either of these would be hundreds of times greater than Spacelab providing
>hundreds of times the chance to fly important experiments.

This is a highly speculative point, since it involves analyzing the politics
of the early and mid 70's, but it can on the surface be proven false for one
simple reason:

Space Station Freedom (or any reasonble space station) requires the Shuttle
to launch.

There are two things unique to the Shuttle that are required to build SSF.
The first is heavy-lift capability (relatively speaking, of course), and
the second is manned spaceflight.  Neither would have been available without
the Shuttle.  The Saturn V, the Mercury and Gemini capsules, and the Apollo
hardware were all already cancelled when the space shuttle came into being
in 1972.  They were NOT cancelled to fund the Shuttle.  In fact, the cancell-
ation had a large impact on the configuration of the Shuttle, as it had to
assume the roles of much of the cancelled hardware.

Without the Shuttle, there would be no heavy lift (even the Titan IV didn't
come into being until 1989) and no manned spaceflight.  Any space station
would require either one or the other (or both) to launch and assemble in
space.  There could be no SSF without the Shuttle, and since ISF requires
man-tended operations, there could be no ISF without the Shuttle either.

Conclusion: Since the Shuttle is a pre-requisite for SSF and ISF, neither
could be built at the expense of the Shuttle.  Point 3 is false.

There were (note past tense) alternatives.  Other hardware could have been
built to meet the needs of heavy-lift and manned spaceflight.  This is where
the speculation comes in.  But whatever could have been built would have had
to face the same Nixon administration, the same OMB, and the same Congress
as the Shuttle did.  To say that any system able to meet the needs of heavy
lift and manned spaceflight would have had vastly different political accept-
ance in the early 70's, in my opinion, is pure speculation.

All speculation aside, we have TODAY a hardware mix that has useful capabil-
ities.  How we use those capabilites today and how we expand them tomorrow
are far more important issues than speculation on what might have been.

Mike

--
Michael Kent                                   [e-mail]
Flight Test Engineer                           Tute-Screwed Aero '92
McDonnell Douglas                              Rensselaer Polytechnic Institute
These views are solely those of the author.    Apple II Forever !!

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

Date: Wed, 16 Dec 1992 19:25:16 GMT
From: "Edward V. Wright" <[e-mail]>
Subject: SSTO vs. 2 stage
Newsgroups: sci.space

In <[e-mail]> [e-mail] (Bruce Dunn) writes:

>        If a DC-1 in SSTO mode can launch 10 tons to LEO and the two stage
>vehicle using the DC-1 as an upper stage can launch 50 tons to LEO, then we
>have the following costs for launching 50 tons:

>DC-1 in SSTO mode:  5 flights needed, incurring 5 DC-1 stage turnaround costs

>DC-1 in 2 stage mode:  1 flight needed, incurring 1 DC-1 stage turnaround and
>1 lower stage turnaround cost.

The 2-stager is a *much* larger vehicle, so your vehicle fabrication
costs will be much larger.


>       I will assert that turnaround cost of the lower stage will not exceed
>the turnaround cost of the upper stage (the lower stage is much less stressed
>than the DC-1 upper stage, and uses cheap kerosene and LOX as propellants).

Think again.  The SSTO recovers back at the launch site.  Your first
stage will splash-down or land somewhere downrange.  It needs to be
retrieved, safed, and returned to the launch site before it can be
used again.  This is not only expensive, it's time consuming.  You're
going to need a lot of extra stages to make up for the down time.

Mating the two stages will take time and manpower also.

Using a different propellent in the first stage means you're
going to have to invest in another set of propellent storage
and loading facilites.  Fueling will be more complex, requiring
more time and manpower.


>Therefore, as far as turnaround costs go, the two stage vehicle costs 2/5, or
>40% as much as the SSTO.

That doesn't follow from anything you've said up til now.  Your second
stage is a DC-1, so that's 100% right there.  The first stage, being
much larger, will be a lot more.


>        A final advantage to the two stage design comes from the time
>necessary to perform turnaround.   Since the lower stage can be inspected and
>prepared for another flight while the upper stage is making an orbital
>delivery, the frequency of flights will be governed by the turnaround time of
>the upper stage after it gets back.

Only if the first stage can teleport.

>Say that turnaround time is 1 week.  If you spend your money on two DC-1
>vehicles and operate them in the SSTO mode, then it will take 5 weeks to
>put 100 tons in orbit (two flights delivering 10 tons each per week).

Or 5 days, flying two flights per day.

>If you spend your money on one DC-1 and 1 lower stage, then the same
>100 tons can be put into orbit in two weeks (two flights, each
>delivering 50 tons).

Of course, you'll only have enough money to pay for half the first
stage.

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

Date: Wed, 16 Dec 1992 19:39:29 GMT
From: "Michael V. Kent" <[e-mail]>
Subject: Terminal Velocity of DCX? (was Re: Shuttle ...)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Brian Stuart Thorn) writes:

I said this:

>>What I don't believe is that you'd get any knowldgeable
>>volunteers to fly a Spacelab mission on a Titan IV.

>Ever hear of the "Manned Orbiting Laboratory"? A Gemini with a very
>Spacelab-like module launched together by Titan III.

Yeah, I've heard of it.  I've also heard that it was cancelled about 25 years
ago, and that none of them ever flew.

Spacelab is very dependent on the Shuttle for life support, power, and heat
rejection.  You couldn't fly it on a Titan IV (which was my point).

Mike

--
Michael Kent                                   [e-mail]
Flight Test Engineer                           Tute-Screwed Aero '92
McDonnell Douglas                              Rensselaer Polytechnic Institute
These views are solely those of the author.    Apple II Forever !!

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

Date: Wed, 16 Dec 1992 18:41:12 GMT
From: Paul Dietz <[e-mail]>
Subject: Terminal Velocity of DCX? (was Re: Shuttle ...)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Gary Coffman) writes:

> The load on a pump also increases linearly with the volume of material
> it has to move. Naturally I was assuming larger combustion chambers for
> the low pressure design so that the mass flow, and thrust, remained nearly
> the same. The two designs lead to different stresses, though. A low volume,
> high pressure pump has different failure modes than a low pressure, high
> volume pump. One is not necessarily better than the other.


But, Gary, while the volume of the combustion chamber is indeed larger
in the low chamber pressure case, the volume rate of consumption of
liquid propellant is very nearly the same, for a given thrust.  The
pumps are pumping liquid fuels -- whose density is independent of the
chamber pressure -- and the low pressure engine needs to pump only
slightly more than the high pressure engine for a given level of
thrust (because of its slightly lower Isp).  You do *not* have to pump
twice as much fuel if the chamber pressure is reduced by half.

Given that the volumes of fuel to be pumped are nearly the same,
the low pressure engine will require less powerful pumps.

    Paul F. Dietz
    [e-mail]

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

Date: Wed, 16 Dec 1992 19:54:16 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Terminal Velocity of DCX? (was Re: Shuttle ...)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Michael V. Kent) writes:

>Spacelab is very dependent on the Shuttle for life support, power, and heat
>rejection.  You couldn't fly it on a Titan IV (which was my point).

For what we have spent on Shuttle we could have built two Freedom
space stations or about 20 or so Industrial Space Facilities. Utilization
of either of these would be hundreds of times greater than Spacelab providing
hundreds of times the chance to fly important experiments.

That is my point.

  Allen

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------129 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: Wed, 16 Dec 1992 20:12:55 GMT
From: "Michael V. Kent" <[e-mail]>
Subject: Terminal Velocity of DCX? (was Re: Shuttle ...)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Gary Coffman) writes:

>Uh wait, didn't you post that SDIO's DCX program cost totalled $1.2 billion?

The DC-X contract was for about $58 million.  SDIO is accruing additional
costs at its NPO, but since the entire NPO is one three-man team, I doubt
that's very much.

I think the DC-Y effort was for $1.2 billion (this sounds low to me, but I
can't dispute it).

Mike

--
Michael Kent                                   [e-mail]
Flight Test Engineer                           Tute-Screwed Aero '92
McDonnell Douglas                              Rensselaer Polytechnic Institute
These views are solely those of the author.    Apple II Forever !!

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

Date: 16 Dec 92 23:18:09 GMT
From: Steinn Sigurdsson <[e-mail]>
Subject: what the little bird told Henry
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Edward V. Wright) writes:


   >Neither the Soviets nor the US had serious contingency plans in
   >place in the race to the Moon.

   Oh?  Diverting an Earth-orbital mission (Apollo 8) into a
   circumlunar flight, because of a rumor that the Soviets were
   going do it first, sounds like a contingency plan to me.  Unless
   you're rewriting history again.

That's not a contingency plan. A contingency plan is
"oh shit, the Saturn pogoed and blew, it will take
two years to fix, we better switch to the Uranus VI,
we just figured the problem with the variable nozzles on
those..."

Of course there were no Uranii in the real world...

|  Steinn Sigurdsson    |I saw two shooting stars last night        |
|  Lick Observatory    |I wished on them but they were only satellites    |
| [e-mail] |Is it wrong to wish on space hardware?        |
| "standard disclaimer"    |I wish, I wish, I wish you'd care - B.B. 1983    |

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End of Space Digest Volume 15 : Issue 560
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