OSP: reliability and survivability

In deciding whether or not to fund NASA's proposed Orbital Space Plane
- a "space taxi" dedicated to crew transport, in contrast to the
current "space truck" - Congressional mavens are making a faulty
assumption. That is that because OSP will be launched on unproven
Delta and Atlas-family rockets, it will be fundamentally no more
reliable than the Shuttle. Because OSP will be costly, it follows that
it makes more sense to upgrade the Shuttle than to build a new
spacecraft.

This is correct on its own narrow terms - rockets tend to explode at
least 1% of the time, despite the best efforts of engineers. However,
putting the OSP on top of the launch stack makes it an inherently
survivable vehicle; rockets can drag the plane clear of a fireball,
and launch debris won't fall onto the vehicle. The OSP becomes its own
ejector seat.

The shuttle, in contrast, can be made more reliable but is inherently
unsurvivable. The Challenger and Columbia incidents only became
disasters because of the Orbiter's placement to one side of the launch
stack. One way round this is to build a B-1B type Crew Escape Module
into the middeck, but this would involve a partial rebuild of the
three remaining Orbiters.

No. Don't upgrade the Shuttle beyond the measures suggested in the
Gehman report. Let's put all our energies into building a reliable,
survivable replacement. Fly the Shuttle only as many times as are
needed to complete the Station, then - ASAP - put these dinosaurs into
mothballs. Time for a change.

Edwin Kite
undergraduate
Cambridge University, UK

"Edwin Kite" wrote in message
om...
In deciding whether or not to fund NASA's proposed Orbital Space Plane
- a "space taxi" dedicated to crew transport, in contrast to the
current "space truck" - Congressional mavens are making a faulty
assumption. That is that because OSP will be launched on unproven
Delta and Atlas-family rockets, it will be fundamentally no more
reliable than the Shuttle. Because OSP will be costly, it follows that
it makes more sense to upgrade the Shuttle than to build a new
spacecraft.

This is correct on its own narrow terms - rockets tend to explode at
least 1% of the time, despite the best efforts of engineers. However,
putting the OSP on top of the launch stack makes it an inherently
survivable vehicle; rockets can drag the plane clear of a fireball,
and launch debris won't fall onto the vehicle. The OSP becomes its own
ejector seat.

The shuttle, in contrast, can be made more reliable but is inherently
unsurvivable. The Challenger and Columbia incidents only became
disasters because of the Orbiter's placement to one side of the launch
stack. One way round this is to build a B-1B type Crew Escape Module
into the middeck, but this would involve a partial rebuild of the
three remaining Orbiters.

No. Don't upgrade the Shuttle beyond the measures suggested in the
Gehman report. Let's put all our energies into building a reliable,
survivable replacement. Fly the Shuttle only as many times as are
needed to complete the Station, then - ASAP - put these dinosaurs into
mothballs. Time for a change.


You guys just don't get it, do you? All technical and engineering analysis
will say that the Shuttle is generally safe and logically speaking it makes
more sense to keep the Shuttle flying for as long as needed. However,
politicians and the U.S. public aren't on the same frequency with engineers.
Their call for a Shuttle replacement is purely based on the *subjective*
feeling that the Shuttle is unsafe and is tainted. Yet, these are the people
that decide wether the Shuttle will be replaced or not. Conclusion: the
Shuttle will be replaced with a decade. As soon as the OSP is flying, I'll
bet you that NASA will present a plan to take the remaining Shuttles out of
service.

Edwin Kite wrote:

No. Don't upgrade the Shuttle beyond the measures suggested in the
Gehman report. Let's put all our energies into building a reliable,
survivable replacement. Fly the Shuttle only as many times as are
needed to complete the Station, then - ASAP - put these dinosaurs into
mothballs. Time for a change.


I completely agree with that assessment and recommendation. The
Shuttle's design is inherently flawed, and it's time for a "fresh sheet
of paper" approach. Now the question becomes "ballistic capsule, lifting
body, or winged vehicle?" In short, are we going to end up with Big
Gemini, the HL-20, or Dynasoar?

Pat

Ultimate Buu wrote:

You guys just don't get it, do you? All technical and engineering
analysis will say that the Shuttle is generally safe and logically
speaking it makes more sense to keep the Shuttle flying for as long as
needed.

I do not agree to this statement. There are several flaws in the shuttle
system,making it unsafe, which could only be solved by a complete
redesign. (Eg. Tank isolation, hydrogen fuel lines which leak every few
launches)

However, politicians and the U.S. public aren't on the same
frequency with engineers. Their call for a Shuttle replacement is
purely based on the subjective feeling that the Shuttle is unsafe and
is tainted. Yet, these are the people that decide wether the Shuttle
will be replaced or not. Conclusion: the Shuttle will be replaced with
a decade. As soon as the OSP is flying, I'll bet you that NASA will
present a plan to take the remaining Shuttles out of service.

Do you really think NASA will be able to build OSP, or any other manned
craft? Considering their performance in the last two decades, I really
doubt OSP will succeed, rather than being scrapped midway because of cost
overruns and underperformance.

The US should put the remaining shuttles into museums, maybe after some
last missions like launching ISS-parts which cannot be done otherwise.
However, the shuttle was a try at building a low cost manned launcher
which did not succeed, and rather than fix what cannot be fixed the US
should build one or more successors incorporating the lessons learned.

Robert Kitzmueller

Ultimate Buu wrote:

You guys just don't get it, do you? All technical and engineering analysis
will say that the Shuttle is generally safe and logically speaking it makes
more sense to keep the Shuttle flying for as long as needed.

The flat failure of any *economic* analysis to support the shuttle is the
problem. Engineering analysis is a strictly secondary problem.

However,
politicians and the U.S. public aren't on the same frequency with engineers.
Their call for a Shuttle replacement is purely based on the *subjective*
feeling that the Shuttle is unsafe and is tainted.

Seeing as we've had two LOO/LOC accidents in 113 flights, it seems to me
there is pretty *objective* reason to doubt the safety of the
shuttle. Engineering analysis may show that if all the right measures are
taken and all the right procedures are followed everything will be OK. No
amount of analysis can guarantee that the procedures will in fact be
followed, nor the measures taken. In fact, we have clear evidence based on
experience to suggest that at least some procedures will not be
followed. The logical conclusion is that the design must allow for the
fact that the vehicle will be operated by humans as opposed to the
flawless engineers assumed in NASA analyses. This requires serious
redesign or outright replacement of the shuttle.

.......Andrew

--
--
Andrew Case |
|

rk wrote:

Or perhaps something a bit different like Rotary Rocket?



I think that whereas single-stage-to-orbit is a nice idea, past
experience has shown that it is mighty difficult to achieve in the real
world due to weight creep on the vehicle. On the other hand, something
along the lines of VentureStar with a disposable wrap-around drop tank
ala Starclipper might have a quite good chance of succeeding with our
present state of technology.
Rotary Rocket always seemed more like a pipe dream than a reasonable
vehicle, and its unique spinning rocket engine reminded me of the giant
flat turbojet inside the Avro Silverbug saucer aircraft...an idea that
seems great and revolutionary...on paper.

Pat

Pat Flannery wrote:
I think that whereas single-stage-to-orbit is a nice idea, past
experience has shown that it is mighty difficult to achieve in the real
world due to weight creep on the vehicle. [...]
Rotary Rocket always seemed more like a pipe dream than a reasonable
vehicle, and its unique spinning rocket engine reminded me of the giant
flat turbojet inside the Avro Silverbug saucer aircraft...an idea that
seems great and revolutionary...on paper.

IIRC, Gary Hudson staten in SSP that Roton had hardpoints where bossters
and/or Tanks could have been attached. So it seems that he took your
position about weight creep into acount ... and used the theoretically
possible SSTO more as a marketing piece and a desireable option, but
planned how to convert Roton halfway to a TSTO as a fallback. This plan
semms sensible to me.

Robert Kitzmueller

(Andrew Case) wrote:

Ultimate Buu wrote:

However,
politicians and the U.S. public aren't on the same frequency with engineers.
Their call for a Shuttle replacement is purely based on the *subjective*
feeling that the Shuttle is unsafe and is tainted.

Seeing as we've had two LOO/LOC accidents in 113 flights, it seems to me
there is pretty *objective* reason to doubt the safety of the shuttle.

That's not an open and shut case. Both losses, while certainly
chargeable to design, could have been avoided by reasonable
operational procedures.

Engineering analysis may show that if all the right measures are
taken and all the right procedures are followed everything will be OK. No
amount of analysis can guarantee that the procedures will in fact be
followed, nor the measures taken. In fact, we have clear evidence based on
experience to suggest that at least some procedures will not be
followed. The logical conclusion is that the design must allow for the
fact that the vehicle will be operated by humans as opposed to the
flawless engineers assumed in NASA analyses. This requires serious
redesign or outright replacement of the shuttle.

Anyone who believes that we can engineer a vehicle of air, ground,
sea, or space that will never suffer a LOC/LOV accident is living in a
fantasy world.

D.
--
The STS-107 Columbia Loss FAQ can be found
at the following URLs:

Text-Only Version:
http://www.io.com/~o_m/columbia_loss_faq.html

Enhanced HTML Version:
http://www.io.com/~o_m/columbia_loss_faq_x.html

Corrections, comments, and additions should be
e-mailed to , as well as posted to
sci.space.history and sci.space.shuttle for
discussion.

The Ruzicka Family a écrit dans le message :
...

"Edwin Kite" wrote in message
om...
In deciding whether or not to fund NASA's proposed Orbital Space Plane
- a "space taxi" dedicated to crew transport, in contrast to the
current "space truck" - Congressional mavens are making a faulty
assumption. That is that because OSP will be launched on unproven
Delta and Atlas-family rockets, it will be fundamentally no more

By the time that OSP actually flys, both the Delta 4 and Atlas V will have
flown many missions, with both commercial and government payloads. Both
systems will be far from "unproven" by that time. In order to actually
FLY
the OSP, there will have to be some modifications made, especially with
regard to avionics, adapter interface, etc. ALL of these mods will be
made
with the intent of actually making the launchers even MORE safe and
reliable. Will they be 100% safe and reliable? No. No space launch
system
ever has been, nor ever will be 100% safe and reliable. But to say that
the
Delta 4 or Atlas V will be unproven by that time is not factually true.

Remember that Ariane V is supposed to be Man-rated ( triple redundancy ).
Would you take a flight on it at this time?

Pat Flannery :

Robert Kitzmüller wrote:

IIRC, Gary Hudson staten in SSP that Roton had hardpoints where bossters
and/or Tanks could have been attached. So it seems that he took your
position about weight creep into acount ... and used the theoretically
possible SSTO more as a marketing piece and a desireable option, but
planned how to convert Roton halfway to a TSTO as a fallback. This plan
semms sensible to me.

One change that did get make was the replacement of the spinning motor
design with a cluster of the NASA Fastrac motors- although the Roton's
design would make it seem a natural for a plug-nozzle engine...as soon
as you start putting drop tanks and jettisonable boosters on it, you run
into a problem with a nondestructive launch abort scenario (one of the
design features of the vehicle was for it to land safely using it's
rotor with its orbital cargo still on board if it suffered a
nondestructive engine failure during ascent) in that all the tankage and
booster rockets would probably have to be dropped for landing weight
reasons, so as not to overstress the rotor system- this probably
wouldn't be much of a problem in regards to the drop tanks, but if the
booster rockets were solid fueled, then you would either have to
terminate thrust on them or ride them to fuel depletion...and that could
put you in a situation where you have still-firing solid motors on the
vehicle, that are generating less thrust in total than total vehicle
weight; which to me sounds like a perfect recipe for the vehicle to stop
ascending, fall tail-end first, nose over, and head straight for terra
firma pointy end first- assuming it hadn't built up much ascent speed at
the time the main motor system failed.

What that means that you don't do what NASA does just because they did. As
you already pointed out, if the ROTON used drop tanks then you drop them when
you have to abort. If you use booster rockets make then hybrids or liquid
fuel. But why assume that ROTON will use solids just because NASA does.

Earl Colby Pottinger

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