CEV PDQ

Henry Spencer wrote:


Exactly. LockMart wasn't going to use *any* of the existing hardware for
VentureStar, and they still concluded that it was cheaper to build new
launch facilities than to buy into maintaining the LC-39 standing army.


But the advantage is that with a Shuttle derived cargo carrier you can
orbit very large payloads in a single piece, as opposed to having to
build them from component parts in orbit. VentureStar had launch pad
simplicity, small infrastructure, manpower needs, and reusability on its
side, but it would have carried a far smaller payload than a SDCC per
launch- so that also has to be figured into both the economic aspect and
the mission capabilities that are desired if we really do intend to do a
manned Mars flight and build a Lunar base.

Pat

Henry Spencer wrote:


BAe's Multi-Role Capsule design, done in the mid-80s, with a capacity
of four people for normal flight and six in a lifeboat configuration,
almost entirely reusable (including propulsion), had an estimated launch
mass of 8t including escape tower.



As soon as you head toward an aerodynamic lifting body design over a
ballistic capsule, you put your weight way up versus your usable
payload capability. It really surprised me when LockMart chose a lifting
body design rather than a simple capsule, given the limited lift
capability that the prospective boosters for the CEV have.
It will be interesting to see which way Boeing goes with this.

Pat

wrote:

How about hanging 2 shuttle SRBs on each side of a Delta IV core?
Launch on the solids only a la Titan 4, airstart the CBC at altitude
(ok some nozzle work required there). Maybe add one of the new higher
powered upper stages when (if) they come on line. For cargo only
flights of course, this combo has gotta have a decent throw weight.



They've got designs going clean up to a cluster of seven Delta IV
booster stages as the first stage of a vehicle capable of putting 94
tons into LEO: http://www.astronautix.com/lvs/delde94t.htm

Pat

Neil Gerace wrote:



Whereas Saturn V carried all components up with it, ensuring that if one
component went tits up, all of the others would too - including the crew.


If the odds are even as regards the possibility of a individual vehicle
failure (say 90 percent reliability, which was probably what Saturn V
was good for), and you need all the parts for a successful mission, then
the fewer launches, the better.
We never had to find out if our escape systems worked, but the Soviets
had very good luck with theirs, including unmanned N-1 missions that
exploded.

Pat

Rand Simberg wrote:

So? We end up with a lot of launches (assuming we can't get
propellant from the moon). Big deal.

Last time I had a house built, I don't recall demanding that it be
delivered assembled on a giant truck.



Assuming that your component parts go up on rockets that have around 95%
reliability (which is around what most have, particularly the larger
ones) and you've got to assemble something from say 20 or more
parts...then you can be pretty sure of losing a part of it along the
way....and that means building back-up parts for all the parts if you
want to be fairly sure that you have all the components you need to
assemble it, which won't be cheap.
The cost of building a lunar base to extract propellant for the ship
would be far more than any savings accrued from not bringing it up from
Earth, at least if only a flight or two to Mars is intended. The Moon
propellant extraction base option only makes sense if you intend to
start doing a permanent Mars base, which is going to be one hell of a
way down the road compared to what we are planning now.

Pat

"Jorge R. Frank" wrote in message
...
"Neil Gerace" wrote in
:

" wrote in
message ups.com...

the DIV has to fly an odd trajectory (due to structural
concerns) that means that there are points in the ascent when abort is
*not* survivable.

Is that bad? Seems to me that it happens to STS as well.

No. That's due to not being able to terminate the SRBs safely, not due to
trajectory as is the case with the D-IV.

Well, I was only referring to the second part of the sentence: "there are
points in the ascent when abort is *not* survivable."

Andrew Gray wrote:

this would be equivalent to
saying that there's a dead-zone during takeoff where you can't try to
do an emergency landing of the airliner, surely?



Stop calling me Shirley. :-)

The Ottopilot

On Mon, 09 May 2005 21:35:49 -0500, in a place far, far away, Pat
Flannery made the phosphor on my monitor glow in
such a way as to indicate that:

If we actually intend to do a manned Mars mission we are going to need
a heavy lift vehicle of some sort,



Many believe this. That doesn't render it a fact.



You are going to end up with a lot of launches if you try to do it with
anything smaller than some of the proposed souped-up Delta IV heavy
variants from the viewpoint of crew life support requirements alone.

So? We end up with a lot of launches (assuming we can't get
propellant from the moon). Big deal.

Last time I had a house built, I don't recall demanding that it be
delivered assembled on a giant truck.

On Mon, 09 May 2005 21:47:38 -0500, in a place far, far away, Pat
Flannery made the phosphor on my monitor glow in
such a way as to indicate that:

Which cuts into your payload weight, and therefore ups your
launch price per pound for large numbers of launches.



That's an interesting theoretical argument, but in practice, what do
you think that Thiokol would do differently in manufacturing a motor
for an unmanned launch that they do for a manned one?



The recovered SRB segments wouldn't have to meet the strict inspection
requirements they now do. After Challenger, Thiokol is probably
extremely paranoid about the recovered booster segments it fills and
ships. I'll bet any scratches or small dents get the segment rejected,
even though they shouldn't really compromise its structural integrity in
any significant way. But they'd be far more likely to use something that
isn't all bright and gleaming on a unmanned launch.
If fact, for warm weather launches, you could use the old style
pre-Challenger booster segments without any real problem.

You could do all those things for manned launches as well. If you
were sensible, anyway.

On Tue, 10 May 2005 19:34:05 +0800, in a place far, far away, "Neil
Gerace" made the phosphor on my monitor glow in
such a way as to indicate that:

"Rand Simberg" wrote in message
.. .

Last time I had a house built, I don't recall demanding that it be
delivered assembled on a giant truck.

If you wanted 10 houses a year built in an area where there are neither
roads nor building materials, a giant truck would look pretty attractive.

If there are no roads, how would the truck get to the building site?

Building roads would look more attractive, since it would be nice to
also be able to get to the grocery store after the house was built.
And I haven't seen anything to indicate ten missions per year.