Strong case for capusle OSP

jeff findley wrote:

(Gene DiGennaro) writes:

I'm kind of a fence sitter as far as the capsule vs wings debate. I'm
partial to winged vehicles simply because in a capsule you have to
rely on a parachute that must unfurl after being stowed for a long
time.

Funny, they seem to work on 6 month Soyuz flights. Furthermore, you
can carry a backup parachute with far less weight penalty than you can
carry backup wings.

I do wonder if the US had flown an equal number of manned
capsule missions as the shuttle has flown, would there be parachute
failures? Soyuz experience doesn't seem to indicate this but I still
wonder.

There was one parachute failure on one Apollo flight. However, Apollo
used three parachutes, so the failure of one to fully inflate didn't
lead to death of the crew. Failure of one wing on a vehicle like the
shuttle has been shown to be unsurvivable.

The proximate cause of the loss of Columbia may actually have been loss
of control: Once all three hydraulic systems read 0/0 the crew was
dead, regardless of aerodynamic effects, or additional structural
damage, due just to the burnthrough. Horizontal landing vehicles have
their own critical failure modes which can kill you just as dead as any
critical failure modes on a VTOL vehicle.

Of course with winged recovery, you have take your heavy wings into
orbit with you. Then they need to be protected during reentry....well
you know the drill.

Wings are heavy, parachutes are lighter. Because of this, you can
build redundancy into the parachute system (e.g. a primary and backup
parachute like Soyuz or three parachutes like Apollo). Furthermore,
you can replace the parachute with a parafoil and have better control
of your landing point, without increasing the mass of the system to
the point where it equals that of wings.

Wings (and all the other systems required just for horizontal landing)
are also heavier than the propellants required to land a VTOL vehicle of
equivalent payload capacity with just rocket braking. I put some
numbers into my launch vehicle spreadsheet, and the propellants required
to land BOTH stages of a VTOL RLV weighed less than the Shuttle Orbiter
systems (including the associated TPS) required for horizontal landing
(from "Space Shuttle").

On a related question, with precision slashdown capabilities, would an
ocean landing be absolutely necessary for a manned capsule? In other
words, could NASA splash down a capsule into an inland lake? This
would eliminate the need for a large naval recovery committment like
we had in the 60's. Also unless the lake was the Great Salt Lake, the
capsule would be coming down in fresh water. I see this as an
advantage in spacecraft refurbishment and turnaround.

NASA already has recovery ships for the SRB's, so why not use them to
recover the capsule off the coast of KSC? This reduces costs by
eliminating the need to transport the capsule for long distances after
landing, and it eliminates the need to add infrastructure to an inland
lake.

Jeff
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Robert Kitzmüller wrote:

McLean1382 wrote:

"Winged spaceplanes will weigh three times as much as capsules,

Except if they get canceled during development, because they cost too
much and provide too little...

However, just before Dynasoar got canceled, it *did* weight about three
times of Mercury (both were single seaters),

That alone doesn't suprise me. If you want the cross-range, you pay
for it in the weight of wings, or the weight of fuel. And compared to
Mercury, the lower planform loading means you can use non-ablative
materials, enhancing re-useability. Mercury wasn't expected or intended
to give that.

and Hermes did weight just
a bit more than Ariane V could carry before it got canceled, and its
performance had shrunken to the level of Sojus...

Robert Kitzmueller

In addition to the above, I understand that some Challenger-inspired
changes to improve abort saety for the crew, were part (though likely
not all) of the weight increase.

Neither Dyna-Soar, nor Hermes were intended to repeat ballistic
capsule performance...

Ralph Buttigeig writes:

Parachutes were never a problem for Mercury, Gemini, Apollo,
and especially Soyuz. What makes you think the Americans can't
build parachutes at least as good as the Russians?

The US parachute splashdowns are a small sample size. Even so, one Apollo
parachute collapse, a sunk Mercury capsule and an Apollo parachute test that
failed and crashed are no grounds for complacency.

Soyuz missions are a much larger sample. Soyuz 1 had a fatal chute failure,
and quite a few Soyuz capsules landed hard enough to injure the crew, landed in
the wilderness hundreds of miles off course, hatch down in a frozen lake, etc.

Will McLean

"Dr. O" dr.o@xxxxx wrote in message .. .
http://www.spacedaily.com/news/rocketscience-03zy.html

This article lists some very compelling reasons why the OSP should be a
capsule.

I await Mr Keller's rebuttal with interest. Clearly a biased article,
but quite compelling none the less.

Interesting comparisons with the Zeppelins. There are advanced designs
for cargo carrying Zeppelin's which could make a comeback. So perhaps
ultimately the way into space will be with single stage space planes,
but for now, it seems capsules are the best options.

"Dholmes" wrote in message
...

"Dr. O" dr.o@xxxxx wrote in message
...
http://www.spacedaily.com/news/rocketscience-03zy.html

This article lists some very compelling reasons why the OSP should be a
capsule.


I really wish he would tone down his hatred of winged vehicles.
His points get lost in it.


Yes, he's certainly overdoing it in some parts, but the overall point is
clear: capsules can be made safer more easily than winged designs. I'm
doubtfull the U.S. public or Congress will approve of a capsule, though.

But if you really think about it: a capsule can be made to land safely
virtually by hand whereas a winged vehicle needs a lot of high-tech to get
it to land safely. A couple of points get lost though: capsules aren't (at
the moment) reusable and the high-G loading factor makes it unsuitable for
medical emergencies.

Joann Evans writes:
That alone doesn't suprise me. If you want the cross-range, you pay
for it in the weight of wings, or the weight of fuel. And compared to
Mercury, the lower planform loading means you can use non-ablative
materials, enhancing re-useability. Mercury wasn't expected or intended
to give that.

But you have to drag those wings up with you on every flight, even
those where you may not need the high cross-range.

Jeff
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"jeff findley" wrote in message
...
But you have to drag those wings up with you on every flight, even
those where you may not need the high cross-range.

Having wings does allow one to design a sizable payload bay for return of
large loads (like SpaceLab, SRTM and other large experiment pallets).
Granted, you don't need that capability every flight, but it's nice to have
a vehicle like that in the stable.

-Kim-

(Alex Terrell) wrote in message

Interesting comparisons with the Zeppelins. There are advanced designs
for cargo carrying Zeppelin's which could make a comeback.



Zeppelins and other LTA heavy lifters have been trying to make a
comeback for about the last 40 years. They always seem to run into a
problem whenever there is wind. Anyone remember the Piasecki job with
four helos on either side? Crashed in the early 80's I believe.

Gene

Kim Keller wrote:
Having wings does allow one to design a sizable payload bay for return of
large loads (like SpaceLab, SRTM and other large experiment pallets).
Granted, you don't need that capability every flight, but it's nice to have
a vehicle like that in the stable.

Given the low mass fraction that basic RCS/control/OMS/re-entry TPS/recovery
represent, one might suppose an unmanned stripped-down capsule chassis
for such large item recovery missions. Rather than make the vehicle fit
the payloads, fit the payloads into a generic stripped down vehicle
rather than a payload module within the vehicle.


-george william herbert

Kim Keller schreef in berichtnieuws
...

"jeff findley" wrote in message
...
But you have to drag those wings up with you on every flight, even
those where you may not need the high cross-range.

Having wings does allow one to design a sizable payload bay for return of
large loads (like SpaceLab, SRTM and other large experiment pallets).
Granted, you don't need that capability every flight, but it's nice to
have
a vehicle like that in the stable.

In 2000, a prototype of an Inflatable Re-entry and Descent Technology was
tested. So the capability to return large loads do not have to be built into
the vehicle, allowing it to be smaller and cheaper, with lower costs for
launch as well. The IRDT folds up to a small package, easily launched.

http://www.space.com/businesstechnol...te_000216.html
http://www.geocities.com/dougiboyuk/YES2main.html
http://www.weblab.dlr.de/rbrt/GpsNav/IRDT/IRDT.html
http://www.2r2s.de/

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