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-   -   The 100/10/1 Rule. (http://www.spacebanter.com/showthread.php?t=96795)

kT March 8th 07 05:14 AM

The 100/10/1 Rule.
 
Danny Deger wrote:

"Reunite Gondwanaland (Mary Shafer)" wrote in
message ...
On Sun, 04 Mar 2007 20:46:23 -0600, kT wrote:

However, one can argue that the expendable SSTO approach puts almost an
order of magnitude more mass into orbit, which is what I am suggesting.

Has anyone ever put anything into orbit with a single stage? I know
we've managed SSTS, Single Stage To Space, but I don't think we've
managed SSTO.


I don't think so. SSTO requires engines for efficent than we have and
requires fuel tanks lighter than we have. Both of these technologies need
to be developed to make a SSTO space craft. NASA tried to develop these
technologies a few year ago and failed in both. I don't know if there is
even a concept out there to make SSTO possible.


Er ... no, it should be doable in aluminum and SSMEs. The SSMEs at
propulsive efficiencies in the low to mid 90s is as good as it's gonna
get anytime in the near future. We're years away from full flow staged
combustion. However, there are clear roadmaps to improvement, and thus
SSTO presents no modern breakthroughs, it's just straightforward R&D and
engineering. The necessary structural efficiencies are clearly in the
range of modern materials and modern structural design techniques.

It's when you start adding all kinds of wings and landing gear that
things get iffy, so I propose just starting out with the basics.

I'm shooting for a 35,000 lb. vehicle. Anything more than that and I'll
need GEM-60s, and then the whole thing falls apart rather quickly.

What we really need, a real simple thing : an RL-60.

--
Get A Free Orbiter Space Flight Simulator :
http://orbit.medphys.ucl.ac.uk/orbit.html

Proponent March 8th 07 11:04 AM

The 100/10/1 Rule.
 
Pat Flannery wrote:
The Atlas H 1/2 stage weighed 8,038 lb according to Encyclopedia
Astronautica; payload to LEO is 8,000 pounds, so with a lightweight
aerodynamic nosecone, who knows?


Is it possible that with the booster engines attached all the way to
orbit, the vehicle could fly a somewhat more efficient trajectory,
therefore boosting the payload a bit? On the other hand, the booster
engines might have to be shut down anyway in order to keep the
acceleration from damaging the structure.


Jeff Findley March 8th 07 02:34 PM

The 100/10/1 Rule.
 

"Danny Deger" wrote in message
...

"Reunite Gondwanaland (Mary Shafer)" wrote in
message ...
On Sun, 04 Mar 2007 20:46:23 -0600, kT wrote:

However, one can argue that the expendable SSTO approach puts almost an
order of magnitude more mass into orbit, which is what I am suggesting.


Has anyone ever put anything into orbit with a single stage? I know
we've managed SSTS, Single Stage To Space, but I don't think we've
managed SSTO.


I don't think so.


True, SSTO has not been demonstrated.

SSTO requires engines for efficent than we have and requires fuel tanks
lighter than we have.


False, especailly for an expendable SSTO. An expendable SSTO isn't all that
hard to do, it's just that no one has tried. The "performance uber alles"
philosophy of your typical aerospace engineer makes them *really* want to
drop some of the heavy bits on the way up, even if it adds complexity and
cost to the design because they always think that the performance gained is
worth the added cost.

As Henry has pointed out many times, a shuttle ET with about six SSME's on
the bottom could put (roughly) the same payload in orbit as the shuttle.
And that's with a generous weight allowance for thrust structure, plumbing,
and etc.

Both of these technologies need to be developed to make a SSTO space
craft. NASA tried to develop these technologies a few year ago and failed
in both.


False. X-33 failed due to a combination of NASA picking the technically
most difficult proposal (there were three competing proposals from different
contractors) and due to lack of incentive on either side to actually make
the vehicle fly. The "obvious" choice to me would have been the DC-X like
proposal. Simpler aerodynamics, simpler structure, simpler engines, simpler
flight control software, and etc.

I'm sure Mary can tell you, from an aerodynamics point of view, how hard it
is to design a winged, or lifting body, unpowered re-entry vehicle that's
stable throughout hypersonic flight all the way down to subsonic flight and
landing. As time went on, the Venture Star (X-33 follow-on) design went
from a lifting body with stubby aerodynamic surfaces to a "lifting body"
with aerodynamic surfaces that sure looked big enough to be called wings.
That was very telling.

I don't know if there is even a concept out there to make SSTO possible.


Then you're not looking very hard, are you? If you look at astronautix.com,
you'll likely find dozens of proposals dating back decades.

Jeff
--
"They that can give up essential liberty to obtain a
little temporary safety deserve neither liberty nor
safety"
- B. Franklin, Bartlett's Familiar Quotations (1919)



Pat Flannery March 8th 07 03:18 PM

The 100/10/1 Rule.
 


Proponent wrote:
Is it possible that with the booster engines attached all the way to
orbit, the vehicle could fly a somewhat more efficient trajectory,
therefore boosting the payload a bit? On the other hand, the booster
engines might have to be shut down anyway in order to keep the
acceleration from damaging the structure.

I assume they carefully worked out to the second when the boosters
became a net deficit to the ascent, and jettisoned them at that point.
Although they each generated over twice as much thrust as the core
engine, their Isp was inferior to it.
290 vs 316 in vacuum respectively:
http://www.astronautix.com/engines/lr895.htm
http://www.astronautix.com/engines/lr1055.htm

Pat

Pat Flannery March 8th 07 03:45 PM

The 100/10/1 Rule.
 


Jeff Findley wrote:
False, especailly for an expendable SSTO. An expendable SSTO isn't all that
hard to do, it's just that no one has tried. The "performance uber alles"
philosophy of your typical aerospace engineer makes them *really* want to
drop some of the heavy bits on the way up, even if it adds complexity and
cost to the design because they always think that the performance gained is
worth the added cost.


You can see the germ of Atlas in North Amercian Aviation's HATV design
from 1946: http://history.nasa.gov/SP-4202/p1-10.jpg
You can just see an engineer looking at that, and thinking: "Now , if we
could jettison the eight small motors once a lot of the fuel was burnt..."

Pat

Danny Deger March 8th 07 04:18 PM

The 100/10/1 Rule.
 

"Danny Deger" wrote in message
...

"Reunite Gondwanaland (Mary Shafer)" wrote in
message ...
On Sun, 04 Mar 2007 20:46:23 -0600, kT wrote:

However, one can argue that the expendable SSTO approach puts almost an
order of magnitude more mass into orbit, which is what I am suggesting.


Has anyone ever put anything into orbit with a single stage? I know
we've managed SSTS, Single Stage To Space, but I don't think we've
managed SSTO.


I don't think so. SSTO requires engines for efficent than we have and
requires fuel tanks lighter than we have. Both of these technologies need
to be developed to make a SSTO space craft. NASA tried to develop these
technologies a few year ago and failed in both. I don't know if there is
even a concept out there to make SSTO possible.


I stand corrected on this. An expendable SSTO is very feasible. The X-33
had problems in large part because it also was attempting to do an
atmospheric entry. The entry requirement added a lot of mass to the system.

Danny Deger




Herb Schaltegger March 8th 07 04:28 PM

The 100/10/1 Rule.
 
On Thu, 8 Mar 2007 09:18:31 -0600, Danny Deger wrote
(in article ):

I stand corrected on this. An expendable SSTO is very feasible.


But doesn't really serve much purpose - staging is a very mature technology
and allows huge improvements in upmass.

--
You can run on for a long time,
Sooner or later, God'll cut you down.
~Johnny Cash


kT March 8th 07 04:40 PM

The 100/10/1 Rule.
 
Herb Schaltegger wrote:

On Thu, 8 Mar 2007 09:18:31 -0600, Danny Deger wrote
(in article ):

I stand corrected on this. An expendable SSTO is very feasible.


But doesn't really serve much purpose - staging is a very mature technology
and allows huge improvements in upmass.


And we are all so grateful for the astronomical increase in costs
associated with staging. All those engines, so little time.

--
Get A Free Orbiter Space Flight Simulator :
http://orbit.medphys.ucl.ac.uk/orbit.html

Herb Schaltegger March 8th 07 05:17 PM

The 100/10/1 Rule.
 
On Thu, 8 Mar 2007 09:40:58 -0600, kT wrote
(in article ):

And we are all so grateful for the astronomical increase in costs
associated with staging. All those engines, so little time.


The "astronomical costs" of hardware are insignificant. The real expense is
the payload, which benefits greatly from being allowed to be bigger than a
grapefruit and mass more than 100 kilograms.

--
You can run on for a long time,
Sooner or later, God'll cut you down.
~Johnny Cash


kT March 8th 07 05:37 PM

The 100/10/1 Rule.
 
Herb Schaltegger wrote:

On Thu, 8 Mar 2007 09:40:58 -0600, kT wrote
(in article ):

And we are all so grateful for the astronomical increase in costs
associated with staging. All those engines, so little time.


The "astronomical costs" of hardware are insignificant.


No wonder space has been so thoroughly colonized already then.

Good job people, kudos all around.

--
Get A Free Orbiter Space Flight Simulator :
http://orbit.medphys.ucl.ac.uk/orbit.html


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