Shuttle delta-V without drag.

Does anyone happen to know how much drag the atmosphere contributes to
a shuttle launch, and the delta-vee that might be possible without it?
(assuming for the moment that you can light it off in vacuum)
Trying to get a number for a graph on size vs drag.

"Ian Stirling" wrote:

Does anyone happen to know how much drag the atmosphere contributes to
a shuttle launch, and the delta-vee that might be possible without it?
(assuming for the moment that you can light it off in vacuum)
Trying to get a number for a graph on size vs drag.

In first stage the drag coefficient (axial force coefficient, zero alpha) is
about 0.7, with a reference area of 2,690 sq. ft. Approaching mach 1 it goes
to about 0.26, and then slowly decays to about 0.2. At second stage the
loss of the SRBs and the associated attach struts lowers by about 0.20 the
coefficient.

Jon

Does anyone happen to know how much drag the atmosphere contributes to

I have read its much worse just at liftoff because of the thicker atmosphere at
sea level.

It often made me wonder if launching from the highesr mountain on earth would
be a improvement

(Hallerb) wrote in message ...
It often made me wonder if launching from the highesr mountain on earth would
be a improvement

Theoretically, yes, other than the obvious logistical problems of
launching from the top of Everest. AFAIR the atmospheric pressure
drops by about 50% by that altitude, significantly reducing drag.

This is, for example, why Kistler's original K-1 plan called for the
spacecraft to be lifted to 80,000 feet or so on a very simple and
basic rocket or jet-powered platform before the main engines ignited:
in a sea-level launch a lot of fuel is burnt getting to that height
through the dense atmosphere, so just lifing it to that height, even
without providing any horizontal velocity, would have reduced fuel
requirements enough to make an SSTO theoretically feasible without too
many exotic materials.

Mark

This is, for example, why Kistler's original K-1 plan called for the
spacecraft to be lifted to 80,000 feet or so on a very simple and
basic rocket or jet-powered platform before the main engines ignited:
in a sea-level launch a lot of fuel is burnt getting to that height
through the dense atmosphere, so just lifing it to that height, even
without providing any horizontal velocity, would have reduced fuel
requirements enough to make an SSTO theoretically feasible without too
many exotic materials.

Mark

I have often wondered about a OVERSIZED jet, say 10 times the size of a 747
used to take a smaller shuttle like vehicle to say 100,000 feet. then detach
the space vehicle single stage to orbit. light boosters and your on your way.

the airplane part which was refuled repeatedly in its way is refuled again and
flies back to base.

(Hallerb) writes:
I have often wondered about a OVERSIZED jet, say 10 times the size of a 747
used to take a smaller shuttle like vehicle to say 100,000 feet. then detach
the space vehicle single stage to orbit. light boosters and your on your way.

the airplane part which was refuled repeatedly in its way is refuled again and
flies back to base.

This idea has been toyed with repeatedly over the years... for
one recent example,
http://www.andrews-space.com/en/corporate/NGLT(200311).html

shows a system in which a large air-breathing jet engine takes off,
circles around to generate LOX from the atmosphere (so the weight of
the oxider isn't needed to take off on the ground), and fires off a
second stage.

This is just one example, there are countless variants out there.

--
Richard W Kaszeta

http://www.kaszeta.org/rich

"Mark" wrote in message

(Hallerb) wrote in message
It often made me wonder if launching from the highesr mountain on earth
would
be a improvement

Theoretically, yes, other than the obvious logistical problems of
launching from the top of Everest. AFAIR the atmospheric pressure
drops by about 50% by that altitude, significantly reducing drag.

This is, for example, why Kistler's original K-1 plan called for the
spacecraft to be lifted to 80,000 feet or so on a very simple and
basic rocket or jet-powered platform before the main engines ignited:
in a sea-level launch a lot of fuel is burnt getting to that height
through the dense atmosphere, so just lifing it to that height, even
without providing any horizontal velocity, would have reduced fuel
requirements enough to make an SSTO theoretically feasible without too
many exotic materials.

Mark

That might be an interesting simulation study. The engines would be a bit
more powerful, you'd have a head start in potential energy, etc. Still,
(OTTOMH) I think it wouldn't be that much of a performance gain, since the
sum of the energy needed for orbit is almost all kinetic.

Jon

"Jon Berndt" wrote in message ...
That might be an interesting simulation study. The engines would be a bit
more powerful, you'd have a head start in potential energy, etc. Still,
(OTTOMH) I think it wouldn't be that much of a performance gain, since the
sum of the energy needed for orbit is almost all kinetic.

Well, the two reasons they gave at the IAF presentation I saw were
that the altitude significantly reduced drag losses, and allowed them
to use engines optimised for vacuum flight rather than have to worry
about compensating for big pressure changes from launch to engine
shutdown... that alone was supposed to give a decent boost in ISP.

Mark