$64 Billion and seventeen years to land on the moon. What's wrong with this picture?

Scott Ferrin wrote:

On Fri, 12 Mar 2004 19:13:59 GMT, (Derek
Lyons) wrote:

Scott Ferrin wrote:

Rockets are not jets.

Yet.

You really need to stop treating todays situation as the eternal
reality.

D.


I realize things aren't going to stay the same for ever but you have
to keep in mind that the market forces that have been driving airlines
and aircraft are not the same as what drives rockets.

Not at the moment, no.

You keep comparing them yet it's not really a valid comparison.

I keep comparing the way folks like you keep treating them with the
way things should, and will be. (Or to put it simply, you make the
same error of treating today's situation as eternal realities.)

Until they find the "killer app" for space launchers they will always be
expensive, low run, vehicles. Just compare the timelines for the
first sixty years of airplanes to the first sixty years of rockets.
Not at all the same.

I point I won't debate. But I don't act like they are going to stand
still and not change.

D.
--
Touch-twice life. Eat. Drink. Laugh.

Jorge R. Frank wrote:

http://hypersonic2002.aaaf.asso.fr/papers/17_5259.pdf

The popular press has, of course, chosen to quote selectively (and
sensationalistically) from this paper:

http://www.usatoday.com/news/nation/...mosphere_x.htm

...and our own Pat has his own selective interpretation, above... :-)


I first ran into a mention of it in Aviation Week and Space Technology,
way back in the late 80's-early 90's; see the posting to Mary Shafer; In
fact the CAIB looked into this during their investigation IIRC, but
quickly dropped it as a possibility.
The description in the first report you cite:
"At hypersonic speeds these clouds may present a corrosion/abrasion
hazard to forward surfaces including
airfoils and windows. These clouds would certainly increase drag and may
result in abnormal operation of
turbojet or scramjet engines. Abrasion of the windshield is possible,
but in the shuttle the windshield would probably
be shielded by the 40-degree angle of attack. Density shear effects – in
this case due to the concentration of ice
particles - could upset guidance, with roll and angle of attack
transients, increased RCS propellant usage and
ranging errors. The magnitude of these effects could vary from trivial
to catastrophic depending on the cloud particle
size, number density and composition. Simulations with extreme density
shears show the vehicle actually skipping
off the cloud. However, these disturbances are more likely to be mild
enough to be survivable. Heating rates would
be unpredictable, because of potentially off-nominal
laminar-to-turbulent flow transition, chemical reactions in
the plasma that might increase the heating by a factor of two, and
energy absorbed by the vaporization of ice.
However, the most severe effect of entry through a noctilucent cloud
would probably be the erosion of the
thermal protection system during the most critical heating region.
Depending on the particle size, sufficient damage
could be done to result in loss of vehicle."
Is a tad disconcerting.

Pat

Jorge R. Frank wrote:

It's possible on the B-2 due to 1) its wings being huge compared to its
(nonexistent) fuselage, and 2) the additional capability to do differential
throttling.

And don't forget the patented Northrop Flaperons on the trailing edge of
the outer wing (Aerilons that can split into upper and lower sections to
act as drag brakes); these probably have a lot more to do with keeping
it pointy end forward than changing engine thrust.
You can see them opened he http://www.sky-flash.com/mildenhall/022.jpg
(The trapezoidal things hanging out the bottom are the landing gear
doors getting ready to close).

Pat

"William R. Thompson" wrote in message
...
I seem to recall that LOX will react explosively with
some organic subtsances even without a source of ignition, but I'm
drawing a blank on the names at the moment.

Sucrose?

(Derek Lyons) wrote:
[...]
And here we have the bias... The confusion between Shuttle MK1M1, (or
MK2) and STS-II. But you are in good company, as NASA fails to
realize the difference as well.


No, I think the confusion is in naming the critters. *I* was using
STS-II the same way older threads have referred to OV-20x's. And
without being able to leverage existing tooling, I don't think it is
worth it.

[...]

STS-II should be a new system, designed an integrated from a clean
sheet.

X-33, OSP winged variants, ... These are all interesting ideas, but
I'm not convinced that we have the technology in hand to make these
critters more practical than the shuttle is, which has big impacts on
how much it costs to maintain and operate them (okay, I think we have
a fighting chance with OSP-W, but it wouldn't be easy).


(And need not be limited to a single type of vehicle.)

Ooops, did this slip out?

[...]
The problem is capsules don't even remotely meet current or projected
requirements. To do so requires EELV capsules *plus* EELV cargo
vehicles.

but capsule people *must* be limited to a single type of vehicle?

Capsules are cheaper than the Shuttle for passengers, but
it's not clear that EELVs can actually replace the full range of
Shuttle capabilities and still be substantially cheaper.

For that matter it's not entirely clear what the required range of
capabilities actually *is*.


If you're just taking mass up, then we have a range of possibilities
that doesn't need wings.

If you're taking mass down, then the choices are more limited, but
there are other ideas than WVs. Lifting bodies, for instance, which
share some of the advantages of WVs for cross-range and g-force, but
without the Leading Edge issue. Parachutes aren't out of the
question. I never got up to speed on Roton, so I don't know if that
was supposed to be cargo-return-capable. Delta Clipper?


And you've still got the launch burden of carrying wings that aren't doing
anything for you except reducing your up-truck capacity.

And increasing your cross range, which increases your number of
landing opportunities and widens your landing windows. The benefits
of this are arguable, but it's existence is not.


Cross-range may be important if you're in a hurry, but what cargo is
in a hurry?

Yes, NASA used the shuttle's cross-range. Because it was there. Does
that mean they needed it? After all, *they* weren't doing the AOA
from the west coast.

/dps

In message , ed kyle
writes
(Mark) wrote in message
. com...
(ed kyle) wrote in message
e.com...
It is enough to provide a 98% first-order Bayesian estimate
of mean predicted probability of success for next launch
attempt.

Agreed, but any viable reusable vehicle should be designed for a
success rate much higher than 98%.

Challenger was lost due the failure of a reusable SRB*.

SRBs are not reusable in any meaningful sense of the word. It's about
as sensible as claiming that SSMEs would be 'reusable' if you kept the
outside of the nozzle and replaced everything else for every flight.


Recovered SRBs include the motor case and structure as well
as flight instrumentation, recovery avionics, the parachutes,
the thrust vector control system, and the range safety
destruct system. The TVC system includes redundant auxiliary
power units and hydraulic pumps. This system and other avionics
are located in the aft section. The forward section also
contains avionics for the recovery system. Both forward and
aft avionics include multiplexer/demultiplexers.

But how much of that is actually re-used?

Pat Flannery wrote:

Except that in this case, you are pancaking into them at multiple Mach
numbers in very thin air.

I think Mary means, is there any reason why tiny ice crystals wouldn't flow
along the shock boundary of the supersonic flow rather than impinge on the
orbiter? Because to actually strike the orbiter, the object would first
have to cross the shockwaves from the nose and possibly the wings, too.
Given the temperature and pressure changes at the shock front, it's hard to
imagine tiny ice crystals from clouds surviving, even if they didn't simply
flow around the vehicle following the shock waves instead.

But that's just my two cents. I hope Mary follows up to correct me if
necessary.

--
Herb Schaltegger, B.S., J.D.
Reformed Aerospace Engineer
Remove invalid nonsense for email.

Pat Flannery wrote in
:

Jorge R. Frank wrote:

http://hypersonic2002.aaaf.asso.fr/papers/17_5259.pdf

The popular press has, of course, chosen to quote selectively (and
sensationalistically) from this paper:

http://www.usatoday.com/news/nation/...mosphere_x.htm

...and our own Pat has his own selective interpretation, above... :-)

I first ran into a mention of it in Aviation Week and Space Technology,
way back in the late 80's-early 90's; see the posting to Mary Shafer; In
fact the CAIB looked into this during their investigation IIRC, but
quickly dropped it as a possibility.
The description in the first report you cite:

OK, let me boil it down into essentials:

may present a corrosion/abrasion hazard
would certainly increase drag
may result in abnormal operation of turbojet or scramjet engines.
Abrasion of the windshield is possible
in the shuttle the windshield would probably be shielded
could upset guidance
could vary from trivial to catastrophic
Simulations with extreme density shears show the vehicle skipping off
these disturbances are more likely to be mild enough to be survivable.
Heating rates would be unpredictable
most severe effect would probably be erosion of thermal protection
sufficient damage could be done to result in loss of vehicle."

Is a tad disconcerting.

Especially if you translate all the "mays" and "coulds" to "wills", and the
"possiblies" and "probablies" to "definitelies", like you did in your first
post.

I stand by my point. Your interpretation is selective.

--
JRF

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check "Organization" (I am not assimilated) and
think one step ahead of IBM.

Pat Flannery wrote in
:

Bizzaro pAT talk back now.
Him say wing gone, him say tiles gone, him say landing gear gone, him
say whole crew gone, him say about 1/4 to 1/2 weight Shuttle now still
there!

OK, sorry, confused your two vehicle proposals together.


--
JRF

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"William R. Thompson" wrote in
:

Jorge R. Frank wrote:

"William R. Thompson" wrote:

ET-

Drawing a blank here. If launch operations expand, though, how
many ETs can Michoud build? I understand that the limit now is 24
per year.

Correct. That's always been the limit, according to the testimony
Robert Thompson gave to the CAIB.

As a historical footnote, the Shuttle was originally sold with the
idea that it would lower launch costs by flying fifty or so missions
per year.
I wonder if the costs of expanding the Michoud plant were factored
into the lower cost claims?

I actually doubt it. There seems to have been a major disconnect between
Mathematica (which authored the original "50-flights-per-year" report) and
the space shuttle program office, which Thompson headed.

Orbiter-

1: A smaller, redesigned wing. They've never used that crossrange
landing ability inherent in the present design, so eliminate the
mass and drag.

As others have said already, this is incorrect. The shuttle uses its
crossrange capability routinely to maximize daylight landing
opportunities. The maximum crossrange actually used is 791 n.mi.,
compared to the flight rule limit of 800 n.mi., and historically the
entry crossranges have been fairly evenly distributed within the
flight rule limits.

Thanks to you (and the others) for pointing that out to me. I had
understood that the wing had excess capabilities required by the
military but not used by NASA.

I'll grant that NASA has never used the crossrange for the *purpose* the
military wanted (a single-orbit mission with launch and landing at the same
site).

--
JRF

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