Re: GRIFFIN'S DRIVE FOR SHUTTLE-DERIVED


"Pat Flannery" <flanner@xxxxxxxxxx> wrote in message
news:11944bd33djk8dc@xxxxxxxxxxxxxxxxxxxxx
>
>
> Jeff Findley wrote:
> >The assumption that NASA needs a launch vehicle bigger than a Delta IV
> >Heavy/Atlas V Heavy is a terribly bad assumption. Launching components
to
> >LEO and docking them together should allow the building of vehicles large
> >enough to return to the moon and go on to Mars.
>
> But that way you end up with the parasitic weight of the rendezvous and
> docking gear on each of the modules, plus the necessity of
> interconnecting their control systems so that they function as one.

This is true, but you're assuming that the parasitic weight matters. It
doesn't matter so much if you're saving money by using commercial launch
vehicles instead of maintaining the shuttle launch facilities and paying the
standing army for a handfull of shuttle derived vehicle launches each year.

Also, some of the systems can be pared down to a bare minimum if you work on
*real* space infrastructure like a reusable LEO space tug. Many "modules"
would be very passive, like LOX or fuel tanks, and would be picked up by the
tug. The tug would then "dock" the module to the vehicle being assembled.
This way, the docking mechanism and control systems on a fuel tank would be
minimal.

> >Furthermore, NASA is supposed to be bound by law to buy commercial
launches
> >whenever it is possible.
>
> NASA may have taken a dim view of the proposed LockMart-Boeing space
> services merger and what it would mean in regard to pricing of
> commercially bought boosters. If you are required to buy commercially,
> and you have a sole-source supplier, then you have a situation where
> that sole-source supplier can charge whatever it wants. Other firms may
> get a slice of the action in the small booster field, but the 500 pound
> gorilla that the merger will create is going to be awfully hard to beat
> in the medium/heavy lift category unless one is willing to to look to
> foreign manufacturers as able to bid on a launch on equal terms with
> American companies.

If NASA build its own shuttle derived vehicle, it will own its own 500 pound
gorilla. From NASA's point of view, it would at least have some control
over its own gorilla. From the nation's point of view, that's one gorilla
too many.

> > Considering how hard of a time Atlas and Delta are
> >having, I'd hate to see NASA turn their backs on commercial launch
vehicles
> >and build their own.
> >
> >Lastly, any sort of shuttle derived vehicle is going to necessarily
require
> >the retention of much of the shuttle ground infrastructure and "standing
> >army". Because of this, it also would retain the high cost of shuttle
> >launches. This is something that even NASA ought to be against. The low
> >flight rate and high cost of the shuttle should not be repeated by
creating
> >a shuttle derived vehicle.
>
> The SRB is a fairly low tech piece of machinery

Surely you jest. It's got to the the most complex SRB ever built. The
thrust vector control system is pretty complex. You've even got a flexible
joint for the nozzle, which is very complex compared to your "typical"
strap-on SRB on the side of an ELV. There is also the recovery system,
which you don't have on other SRB's. Remember the joints aren't simple
either, and I'm talking not only about the casings, but the fuel itself.
Simple SRB's don't have segments and have their fuel cast in one piece to
eliminate joints, which are a possible point for burn through issues.

> , and it could be stacked
> right at the launch site from its component sections, eliminating the
> need for the VAB and the crawler transporter, and then have the upper
> stage and CEV put on it after it was assembled. That would cut down on
> the manpower requirerments. It also has the fact that it is a proven
> design going for it- if considered separately, we've had 216 SRB
> flights with one failure; that makes it hands-down the single most
> reliable large booster rocket ever built, with a failure rate of better
> than .5%.

My gut feel is that if *any* shuttle derived vehicle is built, it will use
the VAB, MLP's, crawlers, and the shuttle pads. Are any other large,
segmented solids stacked at the pads?

> >I hope that Congress realizes this and puts a stop to it now. They
> >certainly don't want a repeat of the shuttle/ISS experience (e.g.
repeated
> >redesigns due to mounting costs).
>
> Unfortunately, one can see that being exactly what happens based on
> recent NASA experience in regards to new spacecraft design. The project
> gets started, then around half way through, we decide that we don't need
> what we are designing or run into a technical snag, and start all over
> again from scratch.

For the station program, this was most often (always?) usually due to cost
overruns. Remember the year that NASA "discovered" $4 billion in overruns?

> They should have a real sit-down discussion and figure out exactly what
> they want and what it's designed to specifically do before they go
> rushing ahead with the design, like they seem to be doing now. The
> Soviets carefully thought out Soyuz before they built it, and the fact
> that they made the right decisions gave them a quite versatile
> spacecraft that could be kept in use at a economical price for decades
> to come.

Now you're going to have Derek after you. ;-)

Part of the success of the Soyuz launcher is the fact that the
Soviets/Russians have figured out ways to use it without requiring it to
grow much, as US launchers seem to do over the years. You don't see the
latest Soyuz launchers sporting large segmented solid rocket boosters like
Titan III/IV.

Delta IV Heavy and Atlas V Heavy are plenty big enough. A real spacefaring
nation would figure out a sustainable LEO architecture capable of flying
missions with these vehicles rather than resorting to a shuttle derived
launch vehicle.

Firstly, an assembly space station at KSC's inclination would go a long way
towards this goal. It would provide power, cooling, consumables, airlocks,
robotic arms, and a reusable space tug to support assembly of interplanetary
craft in LEO. It would enable possible (eventual) reuse of components
returning from the moon (using tricks like aerobraking).

Such a station need not be as complex as ISS. After all, who cares about
the microgravity environment aboard an assembly station? Make it gravity
gradient stabilized and be done with nasty issues like active three axis
stabilization. If you're not doing science aboard it, who cares that you
dump your waste fluids and gasses overboard? The interplanetary craft can
keep its instruments behind protective covers until it leaves LEO.

Jeff
--
Remove icky phrase from email address to get a valid address.


.

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