GRIFFIN'S DRIVE FOR SHUTTLE-DERIVED

wrote:

And even so it's vastly cheaper than an EELV core.

But I wouldn't be surprised if it requires a
second stage that ends up costing as much as
or more than an EELV core.

- Ed Kyle

Perhaps so. Nevertheless, what you wind up with is a two-stage vehicle
costing, say, 1.25 - 1.75 times that of an EELV core. A vehicle that an
EELV would need *3* cores *and* an upper stage to replicate.

On 2005-05-23, Ed Kyle wrote:
GRIFFIN'S DRIVE FOR SHUTTLE-DERIVED

In recent weeks it has become clear that Michael Griffin, NASA's new
Administrator, is maneuvering to win support for development of a new
series of "shuttle-derived" launchers. By stating that he expected the
Crew Exploration Vehicle (CEV) launch mass to grow beyond the
capabilities of any existing launch vehicle, Griffin effectively
leveled the playing field between shuttle-derived and Evolved
Expendable Launch Vehicle (EELV) options.

[SNIP]

What is the message? The message is that Griffin isn't planning on
using their rockets.

This paragraph:

"I report to the president," he told journalists. "The president has
said were retiring the orbiter by 2010, and thats what were doing."

was attributed to Griffin at:

http://www.space.com/missionlaunches...n_shuttle.html

I find it very interesting he specified *orbiter*, and not shuttle,
or STS. Would seem to agree with Ed's article.


Iain

Jeff Findley wrote:


Surely you jest. It's got to the the most complex SRB ever built.


Which isn't saying much- it's basicly an oversized JATO bottle with a
guidence system and swiveling nozzle at the bottom; no turbopumps, no
feed plumbing, no cyrogenics, and a tough case that doesn't need
insulation on it.

The
thrust vector control system is pretty complex.


It's a gimbaling assembly on the nozzle, and hasn't screwed up yet If
you did want to simplify it even more you could do some sort of fluid
injection like on the earlier solids for TVC.

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.


Since we don't really get that much of an economic advantage out of the
recovery of the SRBs anyway, that stuff could be ditched (bad pun) in
favor of increased simplicity and payload capability.

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.



We had one burn through in 113 flights, and we redesigned the SRB after
that for better relibility.



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'd be concerned about propellent sagging, but they have been at least
fired horizontaly- could they be assembled and sent to the pad that way,
and then liftedinto the vertical position?

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



"A billion here, a billion there, and pretty soon you're talking real
money." NASA's (and the government in general's) accounting sucks. But
how many times has a government contractor been found using "creative
accounting" in its billing of the government?



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. ;-)



I've just eaten rice and beans- I'll depth charge him. ;-)

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.



But it's a nifty craft; it can be flown independantly, in a three man
passenger/light cargo varient, in a two man passenger light-medium cargo
varient, or in a unmanned medium cargo varient.


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.



That might be what they have in mind- but we're talking a ten to twenty
year program here minimum...nd do you think there is the political will
out there to carry this off over that period of time? I don't. I'll bet
that CEV dies shortly after the 2008 elections, and that Shuttles will
continue to be launched in leiu of a new system to replace them until we
lose another one, and then manned spaceflight will grind to a halt for
quite a while- I doubt the Russians will be able to keep it up unaided
by our dollars, China will do a few more propaganda flights and then
drop it, and the ESA frankly can't afford it.
As to whether private firms can make a go at it is a very good question,
but I'm not exactly holding my breathe.

Pat

wrote:



It's got to the the most complex SRB ever built.



And even so it's vastly cheaper than an EELV core.



Do we have figures on its cost versus a Delta IV core, with both in the
fueled state? IIRC, Henry Spencer mentioned that the SRB fuel wasn't cheap.

Pat

Ed Kyle wrote:

But I wouldn't be surprised if it requires a
second stage that ends up costing as much as
or more than an EELV core.



You could grab the top stage Delta IVH off of a Delta IV if you wanted
to; diameter is 5.0 meters. The SRB is 3.71 meters in diameter so you
could fair it in without too much trouble.

Pat

Pat Flannery wrote:
Jeff Findley wrote:
Surely you jest. It's got to the the most complex SRB ever built.

Which isn't saying much- it's basicly an oversized JATO bottle with a
guidence system and swiveling nozzle at the bottom; no turbopumps, no
feed plumbing, no cyrogenics, and a tough case that doesn't need
insulation on it.

Pat, please, that is a grossly simplistic analysis of
the Shuttle SRBs. Such ridiculous handwaving is technically
not credible, regardless of whether the SRB is a viable
launcher baseline or not.

The
thrust vector control system is pretty complex.


It's a gimbaling assembly on the nozzle, and hasn't screwed up yet

Actually, I recall we very nearly lost a Shuttle due to
one of the actuators coming close to failure.

If
you did want to simplify it even more you could do some sort of fluid
injection like on the earlier solids for TVC.

A simple concept, but requiring new development and qualification.

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.

We had one burn through in 113 flights, and we redesigned the SRB after
that for better relibility.

One burnthrough and seven or so near burnthroughs.

Redesigned or not, joints are a failure point.


-george william herbert
/

Pat Flannery wrote:
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,

Or, a tug, or using one of the assembled modules as a tug.

Rendezvous and docking requires one or more active spacecraft
and two stabilized spacecraft. Stabilization is far easier
and cheaper (and can be completely passive) than active,
and the cost savings of passive modules is probably worth it
for logistics flights.

plus the necessity of
interconnecting their control systems so that they function as one.

There doesn't necessarily have to be any control system involved...

Consider for example launching a completely empty upper stage
with the lunar or mars vehicle attached, and then fueling it
on orbit with separately delivered LOX from a propellant depot.
Using Atlas V 552 or Delta-IVH you get about 12 tons of "payload"
ito LTO or MTO per EELV launch that way. Enough to do a decent
light lander or transfer stage module. The vehicle stack is
completely integrated on the ground. All you have to do is
add about 60 tons of propellant (50 tons of LOX, 10 of LH2)
and you're set.

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.

Your second and third sentences are mutually contradictory.

Either BoeMart's EELVs cost too much, in which case there is market
opportunity for vendors to undercut, or they don't cost too much,
in which case the government is not paying too much to use them.


-george william herbert
/

George William Herbert wrote:


One burnthrough and seven or so near burnthroughs.


"Near burnthough" is a somewhat vague and essentially useless metric.
Something like 840 GEM 40's have been flown, and only lost a few; but
from all reports, the ones that have been recovered, alogn with the
static test units, have spooked the engineers who've examined them.
"Near burnthough" is what they were meant to do. Saves weight.

Pat Flannery wrote:
Ed Kyle wrote:

But I wouldn't be surprised if it requires a
second stage that ends up costing as much as
or more than an EELV core.



You could grab the top stage Delta IVH off of a Delta IV if you
wanted
to; diameter is 5.0 meters. The SRB is 3.71 meters in diameter so you

could fair it in without too much trouble.


It wouldn't be big enough and it wouldn't have
enough thrust. The proposed SRB-J2S launcher
uses a 90-100 metric ton LH2/LOX second stage
powered by an engine with about the same amount
of thrust (90-100 metric tons thrust). The
5-meter Delta IV second stage only weighs a bit
less than 31 tons and is powered by a wonderful,
but wimpy (thrustwise) RL10B-2 that makes 11.23
metric ton thrust.

It might work if you stretched it and added eight
more RL10s! Or, if you can afford to pay for the
development effort, use four RL60s - a combo that
would provide a more impressive ISP than J-2S, but
would weigh more.

- Ed Kyle