SSTO - what's the point?

Is there any point in SSTO technology? It seems SSTO means any flight
you have a lot of dead weight with you on orbit?

Best,
Vello

vello wrote:

Is there any point in SSTO technology? It seems SSTO means any flight
you have a lot of dead weight with you on orbit?

The whole point is creating a craft so strong and so lightweight, that you
don't have to carry a lot of dead weight into orbit. An SSTO vehicle would
be truly reusable, which, hopefully, would reduce costs considerably. I
believe it was Robert Zubrin who said: "Imagine the cost of an airline
ticket from New York to Paris if the aircraft was built only for this one
trip, and was disassembled after landing never to be used again."

Reusable vehicles make for higher reliability as well.

/steen

vello wrote:
Is there any point in SSTO technology? It seems SSTO means any flight
you have a lot of dead weight with you on orbit?

Best,
Vello

Steen wrote:
vello wrote:

Is there any point in SSTO technology? It seems SSTO means any flight
you have a lot of dead weight with you on orbit?

The whole point is creating a craft so strong and so lightweight, that you
don't have to carry a lot of dead weight into orbit. An SSTO vehicle would
be truly reusable, which, hopefully, would reduce costs considerably. I
believe it was Robert Zubrin who said: "Imagine the cost of an airline
ticket from New York to Paris if the aircraft was built only for this one
trip, and was disassembled after landing never to be used again."

Reusable vehicles make for higher reliability as well.

/steen


That's for sure, reusable thing is at least in theory much less
expencive. But my problem was about SSTO idea - no matter reusable or
not, multistage composition will give much less dead weight on orbit?

"vello" wrote in message
oups.com...
Is there any point in SSTO technology? It seems SSTO means any flight
you have a lot of dead weight with you on orbit?

Who cares about "dead weight"? What matters is cost per lb to LEO.

Fuel to get that "dead weight" into orbit is cheap. LOX is one of the
cheapest fluids on the planet, since it's literally made from air. Even at
today's prices, kerosene is a pretty cheap rocket fuel and the Rusians have
some pretty efficient LOX/kerosene engines.

If you look at today's launch prices (i.e. cost pr lb to LEO), fuel costs
are a very tiny percentage of the overall launch costs.

Jeff
--
Remove icky phrase from email address to get a valid address.

In article . com,
"vello" wrote:

That's for sure, reusable thing is at least in theory much less
expencive. But my problem was about SSTO idea - no matter reusable or
not, multistage composition will give much less dead weight on orbit?

"Dead weight" in orbit is a good thing if it gives you greater
reliability and lower system costs. Propellants are the cheapest part
of getting to orbit and back; losing 1% or so of your vehicles and
payloads to staging-related accidents is ruinously expensive.

A launcher using two parallel stages that has all engines running at
liftoff is nearly as good as SSTO, with the enormous benefit that no one
doubts that it can be done (because it has already been done).

"richard schumacher" wrote in message
...
A launcher using two parallel stages that has all engines running at
liftoff is nearly as good as SSTO, with the enormous benefit that no one
doubts that it can be done (because it has already been done).

And if you're willing to play games like in flight propellant transfer, when
you do drop your empty parallel stage, the other could be completely full of
fuel. This scheme has the advantage that all your engines are started on
the ground, so you can abort the launch if any of the engines shows signs of
trouble at startup.

Jeff
--
Remove icky phrase from email address to get a valid address.

Jeff Findley wrote:
"vello" wrote in message
oups.com...
Is there any point in SSTO technology? It seems SSTO means any flight
you have a lot of dead weight with you on orbit?

Who cares about "dead weight"? What matters is cost per lb to LEO.

Nope. What matters is cost per lb of REAL CARGO to LEO. With SSTO most
of your lb-s will be the plane itself. It's not (just) about fuel. But
for the same weight of real cargo you must have much bigger launch
vechile itself (coz with cargo, all thing must be lifted to LEO) - for
sure much more expencive in construction?

Fuel to get that "dead weight" into orbit is cheap. LOX is one of the
cheapest fluids on the planet, since it's literally made from air. Even at
today's prices, kerosene is a pretty cheap rocket fuel and the Rusians have
some pretty efficient LOX/kerosene engines.

If you look at today's launch prices (i.e. cost pr lb to LEO), fuel costs
are a very tiny percentage of the overall launch costs.

Jeff
--
Remove icky phrase from email address to get a valid address.

"vello" wrote in message
oups.com...

Jeff Findley wrote:
Who cares about "dead weight"? What matters is cost per lb to LEO.

Nope. What matters is cost per lb of REAL CARGO to LEO.

That's what I mean when I say "cost per lb to LEO". If you take the shuttle
as an example, only what's in the payload bay (and cargo on the mid-deck,
and the astronauts themselves) is payload that would counted in the "cost
per lb to LEO" calculation. The mass of the orbiter would be ignored, as
would the dry mass of any upper stage or the dry mass of an SSTO.

My point is, who cares how much dry mass is taken to LEO and back as part of
a reusable launch vehicle? That "dead weight" quantity does absolutely
nothing to impact the cost per lb (of cargo) to LEO.

An SSTO would clearly place more "dead weight" in LEO (compared to a TSTO
with the same payload), but could still cost less to launch, making the cost
per lb (of cargo) to LEO lower. Certainly it would burn more fuel than a
TSTO, but as I've said before, fuel costs are a very small percentage of the
total cost to place payload in LEO.

How could an SSTO be cheaper to operate? There are no staging events to
worry about, so all your engines are started on the ground, so you don't
have to invest time and money to insure that your upper stage engine
actually starts. Also, while the SSTO may have more dry mass than a TSTO,
you've only got one set of hardware to maintain (e.g. engines, TPS, landing
gear, control surfaces, electronics, and etc.). So while much of the
hardware itself would be bigger on an SSTO, at least there is only one copy
to maintain, not two. This reduces maintenance costs considerably, since
you don't have to pay two teams of maintenance crews.

Jeff
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Remove icky phrase from email address to get a valid address.

"vello" wrote in message
oups.com...
Is there any point in SSTO technology? It seems SSTO means any flight
you have a lot of dead weight with you on orbit?

Best,
Vello


Not if you have the right sort of engines - essentially the spacecraft
becomes a spaceplane. The Skylon designed by Alan Bond in the UK works ...
but nobody with fund the thing.

See the site -

http://www.reactionengines.co.uk/mai...tent=downloads