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Friday, February
21, 2003
I have some correspondence on
SSTO
====
Dr. Pournelle
I have perused some of your writings with regard to SSTO. I spent an
hour of so with a spreadsheet and the solver function to create the list
below following the stated ground rules. I created three types of
winged SSTO, all with liquid oxygen but fueled with Methane, Hydrogen, or
RP. The results are in the tables. I didn't spend too much time
on this little project. I hope this follows the definition of doing
one's homework. I expect you meant homework and not dissertation.
The problem that I have is that SSTOs will just be huge. Even
something that has essentially no payload will be huge, that is the nature
of the rocket equation and structures. I also threw in a development
cost. I gave the development cost a SWAG of $60,000 per pound. What
all this tells me, is that SSTOs are doable, just not within economic reach.
If, on the other hand, there was some kind of market for lots and lots of
stuff, then I could envision somebody forking over the development monies,
until then I doubt it. Now you may discount my weights and say that I
am too conservative. What can I say to that? Anybody can make
anything work if they rely on fantasy. I have seen many a fine concept
die an ugly death at the hands of the weights analyst. I suggest that
anybody taking a promising design to a CEO or Congress better have a
reputable weight guy's approval or it and you will get booted out of the
room.
Gigantism is, of course, no sin. However the bigger the system gets,
the more unwieldy if becomes. Consider some huge rocket that suffers
an engine failure on its way to orbit and aborts to Spain. It lands
there and then what becomes of it? It can't go anywhere. Are
they going to build a rocket pad in Spain to get it home? Then, of
course, if the vehicle is small enough to be ferried home on a 747 like the
shuttle, it can't any payload as the charts below show. Thus, with a
gigantic system, they must build in considerations like it can not land
anywhere else on Earth but at its launch site. Now, the system becomes
more complex, more redundancies must be included in the design. It
costs more, masses more and eventually is killed like Venture Star.
I tell everyone I talk to that we shouldn't talk this design or that design
when we consider space transportation, but that we should focus on providing
the market and the design will create itself according to economics and not
political pork. Thank you.
Ground Rules:
Propellant
All tanks oversized by volume 5%
Lox 71.2 lbm/cf
RP 48
lbm/cf MR 2.6 Engine SL T/W 85 ISP(vac) 340
Methane 26 lbm/cf MR 3.5 Engine SL T/W 80 ISP (vac)
375
LH2 4.2 lbm/cf MR 6. Engine SL T/W 50 ISP(vac) 450
· 30,000 feet per second required for MECO
· 8 per cent extra propellant mass for orbital maneuvering
· Propellant tanks are cylindrical with oblate hemispherical domes
· payload volumeà6 pounds per cubit foot. Payload placed between oxygen
and fuel domes
· Liftoff T/W =1.2
· Entry reference wing loading 70 pounds per square foot
· Wing wetted area = 2.2* reference area
· Wing mass = 7.5 pounds * wing reference area
· Body mass = 10 pounds * body wetted area
· Body length to diameter ratio = 5.7
Methane
Payload
GLOW
empy mass diameter (ft)
dev
cost
250,000
13,966,419
828,124 45.12 $
49,687,455,247
200,000
11,979,772
724,767 42.74 $
43,486,018,400
150,000
9,908,666
614,890 39.96 $
36,893,393,498
100,000
8,060,255
510,829 37.06 $
30,649,721,104
75,000
6,539,521
429,812 34.47 $
25,788,720,419
65,000
6,050,954
402,098 33.52 $
24,125,852,257
55,000
5,547,714
373,250 32.50 $
22,395,026,102
45,000
5,026,399
343,008 31.36 $
20,580,479,376
35,000
4,482,000
310,984 30.10 $
18,659,019,815
25,000
3,906,580
276,565 28.64 $
16,593,878,985
15,000
3,286,059
238,664 26.90 $
14,319,849,167
10,000
2,950,741
217,780 25.87 $
13,066,777,997
5,000
2,590,218
194,949 24.67 $
11,696,963,252
Hydrogen
Payload
GLOW
empty mass diameter
develop cost
250,000 12,201,648
1,175,064 55.23 $ 70,503,828,370
200,000 10,702,232
1,049,943 52.76 $ 62,996,577,165
150,000
9,132,970
916,665 49.91 $ 54,999,872,103
100,000
7,462,352
771,548 46.49 $ 46,292,909,556
75,000
6,570,811
692,423 44.45 $ 41,545,377,339
65,000
6,199,597
659,068 43.55 $ 39,544,071,520
55,000
5,818,011
624,501 42.58 $ 37,470,084,784
45,000
5,424,118
588,498 41.54 $ 35,309,856,198
35,000
5,015,281
550,748 40.40 $ 33,044,906,262
25,000
4,587,741
510,815 39.15 $ 30,648,885,753
15,000
4,135,796
468,031 37.73 $ 28,081,852,949
10,000
3,897,961
445,254 36.94 $ 26,715,210,024
5,000
3,650,015
421,295 36.09 $ 25,277,715,602
RP
Payload
GLOW
empty mass diameter develop cost
250,000 21,164,156
1,015,062 48.32
60,903,743,570
200,000 18,286,173
893,034 45.90
53,582,060,834
150,000 15,280,673
763,384 43.08
45,803,047,771
100,000 12,086,031
622,428 39.65
37,345,691,699
75,000
10,380,508 545,483
37.56 32,728,953,595
65,000
9,669,273 512,969
36.63 30,778,160,308
55,000
8,936,837 479,189
35.61 28,751,331,335
45,000
8,178,576 443,865
34.50 26,631,880,276
35,000
7,387,843 406,600
33.27 24,395,972,987
25,000
6,554,452 366,785
31.87 22,007,076,485
15,000
5,661,257 323,395
30.24 19,403,697,758
10,000
5,182,968 299,806
29.29 17,988,348,303
5,000
4,674,735 274,427
28.22 16,465,605,363
(name withheld)
I pointed out that the total
weights he comes up with are absurd: while we are not sure that a 600,000
pound GLOW will have a payload to orbit at all, it will certainly be
close, and it may even have up to 6,000 pounds: it depends in large part
on drag and engine efficiencies, and all those numbers are in the third
decimal place. We need to FLY things to see.
The late Max Hunter was willing to be that if you
fly a 600,000 pound GLOW VTOL system he could "nickel and dime"
it to orbit, and then design a better one that would have the 6,000 pound
payload. I never say anyone win a rockets argument with Max, and that
includes me, and I tried.
USAF/SDIO Project Have Region established that we
know how to build structures that can achieve the mass ratios required to
get a 600,000 pound VTOL ship to orbit, and they are strong enough.
I said as much to my correspondent who replied:
Dr. Pournelle
I spent a brief time attached to an IRAD product development team. We
looked into different types of launch configurations. Unfortunately
money ran out after about a year and I went back to more mundane
endeavors. However, during that time, I was a great--in my opinion--creater
of concepts. Unfortunately, my bane and archnemisis was the weights
guy. I could show him my calculations on the mass per square foot of
pressurized isogrid aluminum with matching FEA and he would show me his
statistical database on weight trends in all kinds of vehicles going back
to the Wright brothers. I couldn't go into a meeting and tout my
concept unless I got Mr. X's ok. Hence, I learned to include a
certain amount of conservatism. Nobody wants to invest billions of
dollars in a SSTO to discover late in the game that you've got weight
growth. As you know, a little bit of weight growth in a SSTO means
that it comes out of payload. Too much weight growth and you've got
zero payload and money down the drain. I was not involved in X-33,
but I watched their oscillations and I knew they were adding mass and
losing capability every time they did a loads/weight iteration. I
may be too conservative in my estimates, but that was just beaten into me
by people who literally laughed in my face. You may say a 5,000
pound payload with a 600,000 GLOW, but get someone to invest $50 million
on a full up design study and see what kind of final GLOW comes out.
P.S.
It's all your fault you know. I was just a kid that liked to read
science fiction until that issue of Galaxy came out crammed with rocket
and orbital mechanics equations. For me, it was a step farther out.
We will get to space eventually, but it will take a market for lots
of launches, and whether that market is tourists, refueling laser ABMs or
something completely different I don't know.
(name withheld)
To which I can only reply, we DID that. The
result was DC/X because the big doubt in those days was whether you could
control a VTOL ship at low speeds and altitudes (you can; we flew it); and
HAVE REGION, which was intended to determine if structures that would meet
the strength and weight requirements for SSTO were possible (they build
them and they were).
The next step was the full 600,000 pound vehicle,
which would have cost in the $1 billion range if that. The DC/X team
thought they could do it for hundreds of millions at most. But the project
was hijacked by Lockheed which promised the Moon and sixpence and
substantial company investment in the winged abortion X-33 which had
irregular shaped tanks, wings that required all kinds of dynamic flight
adjustments because as fuel is consumed the CG changes and other things
happen, and a linear aerospike engine that never worked properly.
The $50 million full up design study isn't the
problem. Much of that was done in SDIO where they ended up with a 1.4
million pound GLOW vehicle to assure some 15,000 pound payload to meet
some mission requirement. Dan Quayle wasn't able to get enough money to
build anything that large, so the result was DC/X which was a 1/3 scale
model of the SSX that Hunter, Graham, and I sold him. That story has been
told here often enough.
The X-33 experience was expensive but not
instructive: nearly everything that happened was predictable and predicted
at least by me.
You do not want wings on an experimental
development X project space ship. You want pure rockets. You want VTOL.
You want to fly.
You want
- Savable
- Reusable
- Fly Early
- Fly often
- Fly higher and faster
And mostly you want to fly. From that we can
learn things about optimum configurations.
X-33 was none of the above.
As to the X-33 people laughing, if I had just
taken all the money and eaten the dream to achieve nothing, I might have a
slightly different emotion. They ought to be ashamed.
The problem is that we do not have enough flight
data to establish what we need to have a savable and reusable ship. And
everyone seems to have forgotten that SSX was an X SHIP, intended to help
us learn how to build an orbiter that would be Savable, etc. Along
came X-33 to siphon off all the money on a final design and which was to
an X ship as a rabbit hunter is to a rabbit.
Jim Woolsey replies
Jerry,
1. I see that the GLOW estimates are based on the
not untypical 1.2 - 2% payload fractions which one might expect from many
SSTO designs. Wasn't the Delta Clipper series anticipated to have a better
payload fraction than that? From somewhere my backbrain has dredged up 3 -
4%.
2. The thing that scares me more is the estimated
$60,000 /pound GVW (?) cost for development of the vehicle. Where on EARTH
did that number come from -- is that what Lockheed was estimating to get
the X33 into operation? Looking at his figure for RP-1 and 150,000 lb
payload, that's 12 Mlb GLOW (70% more than the Saturn V) and an estimated
development cost of $45.8 G to get a Saturn V class payload capacity back
into operation. If that's not at least 5 dB high.....? Note that your
correspondent's estimate (presumably in 2003 dollars) for the planned
15,000 lb payload capacity of the Delta Clipper is almost 15x the
development cost you estimated. (Hum..take the $15 G estimated for
(mid-'90's) R&D of the Boeing 777 (Business week article about Boeing
last summer), divide by the empty weight (from OL sources) of 310,000 lb,
and we get $50,000/lb. IS that the right ball park for R&D of new
aerospace systems?)
That is REALLY the critical question. It looks like
we get the $60,000/lb figure (plus/minus) if Boeing or Lockheed does the
work. Why shouldn't it be $6,000/lb? Inquiring minds want to get to orbit
without having to worry about high g's.
Jim Woosley Jimwoosley@aol.com
If Boeing or Lockheed does it, we may expect it
to cost a lot more. In fact it will cost as much as you have. And the
result will be little to nothing. X-33 was the demonstration of that. For
all that money we got bupkis, zilcho, nothing flew, nothig worked. But it
sure paid some expensive people for a couple of years.
Try prizes. That might work. My name withheld
correspondent is one of the better people involved with Big Aerospace, and
I welcomed his entry to the discussion for precisely that reason.
Now you see what we face.
Try prizes. But of course Big Aerospace will
fight that.
As witness:
Dr. Pournelle
The most daunting criticism of my homework was that
I had too much weight. I must tell you that's a first in my experience and
quite refreshing. The HAVE REGION Program was brought forward as the
talisman of a new era in structures. I admit I don't know much about HAVE
REGION but let me throw in this little story. Several weeks ago they had
the Joint Strike Fighter story on PBS. One of JSF's requirements was short
field take off and vertical landing. The JSF program was a BIG DEAL for
Lockheed and Boeing. Winning it would be worth tens maybe hundreds of
billions of dollars. Yet there wasn't that much talk about advanced
materials. Weight is critical on vertical takeoff airplanes. Boeing tried
to make a wingskin out of thermoplastic material and failed. These weight
critical birds represented the promise of a lot of money to the respective
contractors. Yet they were built with the basic Aluminum, Titanium, and
thermoset composite. Nobody said anything about metal matrix composites,
exotic composites etc. I would have thought that the HAVE REGION materials
would have percolated down to such important programs. Also, two rockets,
the Delta IV and Atlas V have been developed since HAVE REGION. These
vehicles are made from machined Aluminum. I can conclude that the promise
of HAVE REGION remains a promise. Why hasn't the industry utilized these
vundermaterials? I don't know. If anybody has an answer to this, it would
be very interesting.
You talked about DCX. I must tell you that I have my
reservations about VTOVL vehicles. I do like some concepts more than
others. Kistler Aerospace demonstrated a vertical landing concept for a
rocket without using one cent of government money. It is called a
parachute. One could say that a thirteen-year-old kid with a model rocket
demonstrates a larger flight envelope than DCX. Of course a single stage
vehicle will be too big for a parachute and thus will need the exotic
landing method. The exotic landing method makes the vehicle capable of
being a single stage. Is this an example of a tautology? Kistler decided
on two RP stages with parachute landing for both. And their web site
doesn't talk about exotic materials either.
I never liked the Douglas X-33 version because it
looked like it re-entered with its center of mass behind its center of
pressure. In the world I know shuttlecocks don't fly backward. I know that
they would work this problem with lots of exotic control authority, but
that's just one more thing to go wrong. I've always liked the backwards
re-entering versions with the plug nozzle engines like ROMBUS et al. The
back end is hot on ascent, it might as well be the same on descent. Then
we could have extra hydrogen in the tanks to run through the engine
coolant lines on re-entry and we would get the classic "ablator in a
tank." I think you guys were too hot on DCX to get something done
when in reality you needed to develop the plug nozzle first.
Finally, you did lose a rocket fight. You may not
know it though. When it became obvious that the government was not going
to fund the 600,000 GLOW test vehicle, did anyone approach Douglas with
this proposal? "Let us built it ourselves. Sure it will cost us a
Gigabuck, but if we do it ourselves, we own the technology and will be a
step ahead of everybody. Once it rolls out the door, the government will
feel obligated to fund the test program. The second version will give us a
revenue stream. It will enable us to be first in space
transportation."
If nobody made that presentation then you lost by
default. If that presentation was made, you still lost because the
flinty-eyed money men didn't believe you. Or maybe the corporate types
were too addicted to NASA largesse to make that kind of brave decision. If
the answer is the later, we need to get rid of NASA or find new
corporations.
(name withheld)
In other words, if a small program like DC/X
which was designed to show you guys were full of it when you told us it
couldn't be controlled, gets built on time and in budget and does what it
was supposed to do, it is useless because it didn't solve all the other
problems.
As to the rest of that, ye gods.
It's all my fault. I didn't talk Douglas into
building it on their own, in competition with Lockheed which was getting subsidized
to waste money on X-33. Ye gods man, OF COURSE the
corporate types were too addicted to NASA largesse to make that kind of
brave decision. Who in the world ever
suspected otherwise? But it's my fault. Thanks.
What in the world does plug nozzles have to do
with development of savable reusable ships? Other than the standard
nonsense that if a project doesn't solve all problems and fix the problem
of contamination in the mess kits and athlete's foot in desert troopers,
then it's not worth doing?
The SSX program was intended to demonstrate some
concepts and prove some technologies. The X-33 came along and said
"spend a lot more and we'll solve all the problems at once, and that
incremental approach is a waste of time and money." So the SSX
was abandoned and we got X-33, VENTURE STAR, and I wish everyone well of
it.
And note that parachutes are now, somehow, the
solution to landing problems, as if anyone would use them for routine
operations.
As to us "losing a rocket fight," just
who the heck do you think was on my team? The Citizens Advisory Council on
National Space Policy is a volunteer organization that paid its own way to
conferences, and was fed at them largely through the generosity of Larry
Niven. We put up some of the participants at our house to help save on
hotel expenses. General Graham's High Frontier was supported by voluntary
contributions, and Dan Graham not only didn't take a salary but put some
of his pension into the organization. We didn't have any big government
organization or any NGO paying our bills, and the only way I participated
in the "summit" in DC, and presented my case to the Congress,
was if I paid for a ticket to DC on my own credit cards, and stayed with
friends like Wayne Rash and Barbara Marx Hubbard when I was in DC; or
sprang for grand accommodations in the Army/Navy club.
We did get the DC/X built and for a while there
it looked like they might actually fund some real X projects, SSX among
them. Had that been done, I suspect we would be a big ahead of where we
are now.
But it wasn't done, and we got X-33, Big
Aerospace's answer to the X programs.
So far have we come. So far have we come.
The first chart (methane, I believe)
contains the following line:
Payload GLOW empy mass diameter (ft) dev cost
25,000 3,906,580 276,565 28.64 $ 16,593,878,985
Compare this to the Shuttle.
Loren C Wilton
Indeed.
/Enter irony mode
But of course that approach can't be
tried. Too big and too heavy and we all know Shuttle is better because it
employs the Standing Army. After all, 20,0000 jobs are at stake.
/leave irony mode
Continued below:
Rod McFadden asks
Now why aren't there any pictures of Jerry Pournelle
wearing a costume like this? http://www.ghg.net/redflame/super1.html
To which I can only say Deo Gratia...
And we have
What Drudge doesn't discuss is the relative
vulnerability of the US vs Iraq infrastructure to such weapons.
>From http://www.drudgereport.com
Pentagon Leaning Against Use Of E-Bomb Against Iraq
Thu Feb 20 2003 10:16:46 ET
The U.S. military has developed a weapon that can
permanently disable electrical and telecommunications systems and has
debated the possibility of using it in any military assault against
Baghdad, the WALL STREET JOURNAL reported on Thursday.
MORE
The new weapon -- known as the 'e-bomb,' for the
high-velocity electromagnetic pulses it discharges -- hasn't yet been
tested in battle. But some midlevel Air Force commanders have said that
using such a weapon, which was long in development but veiled in secrecy,
would give the U.S. a decisive initial advantage in a war with Iraq.
Top Pentagon and military-service officials are
leaning against using the e-bomb, though.
They are concerned its use could alienate the Iraqi
populace by crippling Baghdad's phone and electrical systems and, hence,
the city's hospital and emergency-services infrastructure.
Developing...
I would think the conclusion here is obvious.
Dan Spisak:
It's come to my attention recently that model
rocketry, something I grew up with as a child, is now in danger of being a
casualty of the Homeland Security Act. There is a bill embedded in the HSA
called the Safe Explosives Act which would require transportation
companies to license their employees under new regulations with the ATFE
requiring more stringent background checks. The problem with this is
employees currently working who don't pass would have to be reassigned or
restricted to access to their companies shipping, storage, and receiving
areas. Shipping companies simply do not want to take on the additional
legal burden and so are dropping the cargo that is causing them problems.
The first of these companies to do this is UPS, with rumors of FedEx
considering doing the same. If other transportation carriers follow suit
it would mean that all solid rocket motors would be nigh impossible to
ship legally within the US. The would include even the very small Estes
model rocket engines and motors under 62.5 grams of propellant. More
information and detail can be found here at:
http://www.space-rockets.com/arsanews.html
It really gets me mad when I see stuff like this.
Something like model rocketry has nothing to do with terrorism nor does it
have any ability to truly threaten American's safety when they are used. I
wish stuff like this wouldn't happen but I guess airline safety was just
the precursor to far more stupid restrictions on our lives.
-Dan S.
The purpose of government is to hire and pay
government employees; why are you astonished that they will think of ever
more ingenious ways to show they are needed and need to hire their friends
and relatives and increase the size of the payroll?
Freedom and liberty aren't Heaven and don't solve
all problems. They're just freedom and liberty. And they don't pay
government payrolls.
And Paul Walker
I could be wrong, but isn't this a little over the
top?
http://www.kansas.com/mld/kansas/5198721.htm
No comment needed.
....Niven's imagination made
manifest.....
Chris Christopher CAPT Chris Christopher, USNR Staff
Director, Navy Marine Corps Intranet Office Deputy Director for Future
Operations, Communications, & Business Initiatives 703-685-5510
chris.christopher@navy.mil
NMCI Web Site: http://www.nmci.navy.mil
------------
'DENIM' SOLAR PANELS TO CLOTHE FUTURE BUILDINGS By
Jenny Hogan New Scientist February 15, 2003
http://www.newscientist.com/news/news.jsp?id=ns99993380
Buildings of the future could be "clothed"
in a flexible, power-generating material that looks like denim. The
Canadian company developing the material says it can be draped over just
about any shape -- greatly expanding the number of places where solar
power can be generated.
The inventors hope their power-generating material
will enable architects to design complex, curvy buildings that can
nevertheless carry solar cells. One day, consumer products such as
personal stereos and cellphones might also harness "denim-power"
to charge their batteries.
Unlike conventional solar cells, the new, cheap
material has no rigid silicon base. Instead, it is made of thousands of
inexpensive silicon beads sandwiched between two thin layers of aluminium
foil and sealed on both sides with plastic. Each bead functions as a tiny
solar cell, absorbing sunlight and converting it into electricity. The
aluminium sheets give the material physical strength and act as electrical
contacts.
<snip>
Well, gee, I thought I had a hand in that book,
in fact, I thought it was me who went down to my neighbor Ed Begley's
house (which is covered with solar cells and even includes a two-axis
steerable collector) to tell him we were naming the cloth after him. And
it may even have been Steve Barnes who actually wrote in the roll-out
cloth although the concept was pretty obvious from other technologies we
had given Beowulf's Children...
But I'm used to this sort of thing....
Again no comment needed:
Dear Dr. Pournelle:
Thank you, thank you, for
your link to the NY Times Magazine article by Ms. Johnson. Never,
EVER, have I had my outlook on life so shaken, my pre-conceived opinions
held up to such a scathing light, or my prejudices laid out for my own
uncomfortable re-examination. This article was absolutely brilliant. At
once kind, scathing, non-judgmental, philosophical and open minded, it
stands as a monument to rational thinking for all of us everywhere.
Reading it made me ashamed of the thoughts and opinions that I have held
regarding disabilities. Thank you, and all blessings upon Ms. Johnson.
Larry McGinn
=================
Subject: Domestication
I was under the impression that there were a number
of species that were still in the process of full domestication.
The one that comes to mind first is Sugar Gliders (Petaurus
breviceps), which are marsupials from Australia. In nature, they are
gregarious, which means they have good potential for domestication,
unfortunately, nobody has figured out how to litter-train them yet.
More info on Sugar Gliders: http://home.earthlink.net/~boakes1/index.html
I think the question of what purpose domestication
of a given animal has is a much more compelling argument. Who WANTS a pet
wolverine? For that matter, evidently skunks are good pets, but I don't
know many people willing to keep one.
Anne Guglik
Gotta be a hard charger, 'cause life is smokin'.
Heh.
g
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