The 100/10/1 Rule.

I wrote:
No actual SSTOs, yet. There have been several SSTO-capable expendable
rocket stages built... The S-IC and the Titan II first stage were
both in the right ballpark... straightforward Atlas and Delta
variants could do it too.

Addendum: And there have been several rediscoveries of the fact that if
you put six or seven SSMEs underneath an ET, even with generous allowances
for things like thrust structure, it makes orbit with about the same
payload as the shuttle.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

On Mon, 05 Mar 2007 09:42:23 -0600, kT wrote:

Alan Jones wrote:
On 4 Mar 2007 08:29:52 -0800, "Frogwatch"
wrote:

On Mar 4, 11:28 am, "Frogwatch" wrote:
On Mar 2, 4:42 pm, kT wrote:

I've been simulating single stage to orbit (SSTO) launch to low earth
orbit (LEO) in orbiter space flight simulator for a little while now.
In order to increase this payload, the obvious solution is converting
the rocket itself into payload.

BTW, why ssto, wouldnt tsto give better payload ratio?

Certainly, but kT is playing some sort of game with SSTO.

It's not a game, it's a fully qualified space simulator.

I was not referring to the simulator. I have not even looked at it.
Of course even a game or entertainment software could incorporate an
adequate simulator.

If you were even half way serious, you would first state your project
or mission goals, and use that to define requirements. Then you would
evaluate all the available launch vehicles to find the one(s) that
meet your launch requirements at the lowest cost. Then you would do
many launch vehicle design trade studies to see if you could design,
develop, build, test, finance, and use a launch vehicle of your own at
a lower cost than other available launch vehicles. Of course you have
to consider not just the cost of development, but also the lead time
required and the program risks. Your initial trade studies would
likely show that two stage to orbit is cheaper and less risky that
SSTO.

What you appear to have done is exercised a simulation program and
"discovered" that a big LH single use single stage rocket using SSMEs
can achieve orbit, but the payload mass fraction is low. You then play
the game, GIVEN (or considering only) a SSTO vehicle, you contrive a
use that enables you to claim a substantially larger payload mass
fraction. You propose building a space habitat, say Sewerville, from
the orbiting SSTO vehicle(s), and accounting much of the remaining
SSTO vehicle mass as payload to make the SSTO numbers look better.
That is all fine within the rules of your game. However, you ignore
the possibility that nobody may want to live, work, or visit
Sewerville. And you ignore the likely possibility that Sewerville
could be assembled at a lower cost without the SSTO constraint.


SSTO itself is just an engineering challenge, not the most economical
way to achieve orbit. Most SSTO studies postulate a fully reusable
vehicle to achieve some level of economy, but the margins, payload
performance, and real costs just are not competitive. kT's
cannibalistic SSTO vehicle seems pointless.

I'm not cannibalizing anything, I'm designing it all in from scratch.

No you are not. You are designing Sewerville from the remains of your
SSTO vehicle. However, given the game that you are playing,
cannibalizing may not be the right descriptor.

Everything is used as is. At the most, it will require a space suit to
get into the hydrogen tank to seal the ports. All the the pressurization
hardware can be used as is. If anything, I'll be adding hardware to it.

At the most...

What pressurization hardware? Surely the "pressurization hardware"
required for Sewerville, differs from that needed by the SSTO vehicle.
I'm sure you will be adding hardware. Take a look at Skylab, Salyut,
and ISS, and estimate the mass of the additional hardware.

"Reunite Gondwanaland (Mary Shafer)"
wrote:

Has anyone ever put anything into orbit with a single stage?

No.

(I just thought an actual answer ought to be here along with the dozen
coulda-mighta-if ya's...)

Monte Davis
http://montedavis.livejournal.com

On Mar 6, 3:26 am, (Henry Spencer) wrote:

Interestingly enough, both the Titan II first stage and the S-IC had lower
tank mass, in proportion to contents, than the Atlas E did. (Some of the
other Atlas variants may have done better, but I don't have numbers for
them handy. Atlas tank-wall thickness got dialed up and down to suit the
application.) Mind you, the Titan stage benefitted from higher propellant
densities, and the S-IC from sheer scale.

There was a proposed S-IC stage and a half derivative, the S-ID. It
would drop the 4 outer engines (to be recovered) and was capable of
orbiting 22 tons.
I wonder if it would have had a lower cost than 2 stage EELVs.
The up side was retaining heavy lift capacity.
http://www.astronautix.com/lvs/saturnvb.htm

Charles Buckley wrote:

I remember the thread Scott refers to. IIRC, there is an amateur
group out in CA that is using that as its baseline since the
supersonic milestone by amateurs has been met. Spaceflight is
the next amateur milestone.


The article actually had a picture of the rocket; it was pretty
hilarious-looking.

Pat

Henry Spencer wrote:
Addendum: And there have been several rediscoveries of the fact that if
you put six or seven SSMEs underneath an ET, even with generous allowances
for things like thrust structure, it makes orbit with about the same
payload as the shuttle.


What about RS-68s?

Pat

Pat Flannery wrote:

Henry Spencer wrote:
Addendum: And there have been several rediscoveries of the fact that if
you put six or seven SSMEs underneath an ET, even with generous
allowances
for things like thrust structure, it makes orbit with about the same
payload as the shuttle.

What about RS-68s?

You would be hard pressed to get an RS-68 to go single stage.

The T/W ratio is twice the SSME, and the Isp is lower.

Plus it's a ... ahem ... hard starter.

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

Pat Flannery wrote:

Charles Buckley wrote:

I remember the thread Scott refers to. IIRC, there is an amateur
group out in CA that is using that as its baseline since the
supersonic milestone by amateurs has been met. Spaceflight is
the next amateur milestone.


The article actually had a picture of the rocket; it was pretty
hilarious-looking.

I noticed that cool geocities site you posted immediately went over
bandwidth. How long do I have to wait for that to come back online?

Did anybody think to download any images off of it?

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

"Monte Davis" wrote in message
...
"Reunite Gondwanaland (Mary Shafer)"
wrote:

Has anyone ever put anything into orbit with a single stage?

No.

(I just thought an actual answer ought to be here along with the dozen
coulda-mighta-if ya's...)

To be fair, no one has ever tried since an expendable SSTO doesn't make a
whole lot of sense. If you're building an expendable, dropping heavy bits
(like engines or entire stages) makes sense.

I suspect that the first SSTO will either be reusable or will be a
demonstration as part of a program to develop a reusable SSTO.

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)

You would be hard pressed to get an RS-68 to go single stage.
The T/W ratio is twice the SSME, and the Isp is lower.

Isn't the engine T/W somewhat irrelevant? You need a suitable mass fraction of
the whole stage to get to orbit, and the engine mass surely is only a small
fraction of the total dry weight.

Jan