The 100/10/1 Rule.

"Jeff Findley" wrote in message
...

"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.


Does it? I mean with a SSTO you know everything is working at lift-off.
You eliminte staging issues and can save mass on interfaces.

Not sure that really makes it a winner, but it's not 100% clear-cut to me
that it might not be worth it either.


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)


--
Greg Moore
SQL Server DBA Consulting
sql (at) greenms.com http://www.greenms.com

Jan Vorbrüggen wrote:

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.

You can easily simulate this in orbiter to first order approximation. I
just haven't bothered to do it yet, because the way it stands right now,
if I want to fly either the RS-68 or the RL-10, I can fly the Delta IV.

In my SSME based test vehicle, engine weight is 20%.

Everything that has mass is relevant to SSTO.

--
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kT wrote:

Jan Vorbrüggen wrote:

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.

You can easily simulate this in orbiter to first order approximation. I
just haven't bothered to do it yet, because the way it stands right now,
if I want to fly either the RS-68 or the RL-10, I can fly the Delta IV.

In my SSME based test vehicle, engine weight is 20%.

Everything that has mass is relevant to SSTO.

Actually I mispoke, the RAW mass of the RS-68 is twice the SSME.

You're right T/W is somewhat less important here. I think it's in the 50
to 1 range.

--
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"Jeff Findley" writes:

To be fair, no one has ever tried since an expendable SSTO doesn't make a
whole lot of sense.

It could make sense by cheaper production and easier testing, since you
need only one set of tanks, engines, navigation soft- and hardware and
no staging equipment. Something like a "big dumb SSTO" might make sense
when you're planning to do a lot of launches and require cheap
production. The GLOW will be much larger for a given payload, but since
this is mainly fuel and tankage...

Nothing of all this really matters in the real world right now, though.

Jochem

--
"A designer knows he has arrived at perfection not when there is no
longer anything to add, but when there is no longer anything to take away."
- Antoine de Saint-Exupery

Jeff Findley wrote:
"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.

So what are you gonna show up in the ISS in?

I'd prefer to bring an engine, an oxygen tank, a hydrogen tank, a
complete GNC and RCS, a fuel cell, electrolyer, some solar panels and
some sort of radiator and an control moment gyro system. Plus food. Even
the pressurization system can be almost used as is. It's all good to go.

If you're building an expendable, dropping heavy bits
(like engines or entire stages) makes sense.

Not if all you have is one engine. A fully throttlable full flow staged
combustion engine with a channel wall nozzle would be great. I'm stoked.

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.

Of course it is, that's what I've been saying all along - incremental
development. I see an awful lot of people yukking it up here who are
just plain unwilling to take that first step. I don't know if that is
intellectual laziness, apathy, ignorance or good ol' US irrationality.

--
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"Reunite Gondwanaland (Mary Shafer)" writes:

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.

Would you count the 1958 SCORE (Signal Communications Orbit
Relay Equipment), allowing that the Atlas B didn't shed a *whole*
stage on its ascent?

--
Joseph Nebus
------------------------------------------------------------------------------
Can we argue the definition of 'stage' until all comprehension
is lost and only nitpicking remains?

In article ,
Joseph Nebus wrote:
Has anyone ever put anything into orbit with a single stage? ...

Would you count the 1958 SCORE (Signal Communications Orbit
Relay Equipment), allowing that the Atlas B didn't shed a *whole*
stage on its ascent?

Alas, realistically, the classical Atlas -- which launched the orbital
Mercury flights and several other things, in addition to SCORE -- has to
be deemed a two-stage vehicle for this purpose.

It didn't drop a whole stage, no, but it dropped most of the heavy parts
of one. (And some parts of the "upper stage", too -- notably, the entire
tank-pressurization system departed with the booster engines! The gas
left in the mostly-empty tanks was sufficient to keep them pressurized
thereafter, aided by hydrostatic head from high acceleration.)
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

In article ,
Pat Flannery 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?

Haven't done the analysis, but my gut feeling is, not so good -- this is
one place where the RS-68's lower performance really does hurt.
--
spsystems.net is temporarily off the air; | Henry Spencer
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In article ,
Jeff Findley wrote:
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.

An expendable SSTO is not a ridiculous idea, if you're building a new
expendable from scratch (rare), understand that gross liftoff mass is not
an important figure of merit (also rare), and are willing to consider an
aggressive and unconventional design for the sake of secondary advantages
like simplicity and not dropping bits downrange (even rarer). If I were
funded to build a new low-cost expendable and given a free hand on the
design, I'd seriously consider making it SSTO or very nearly so.

Mind you, I'm inclined to agree that it's not likely to happen. Most of
the people who are willing to contemplate aggressive, novel launcher
concepts will be more interested in reusables, and most of the people
building new expendables are constrained to be risk-averse.
--
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"Charles Buckley" wrote in message
...


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.

Does SpaceShipOne qualify?