new topic

>
> Ref:[pokchoy@... Mon, 24/06/02 @ 17:51 -0400]
> > Hello again
> > Since my personal 'hot button' is relative low tech
> projects that we
> > non-NASA types can try, I want to propose another old idea.
> > Why not suspend a rocket from a huge balloon? Take to
> 150000ft and drop it
> > into parabolic trajectory.
> > Sounds equally doable.
> > Any thoughts?
>
> Why would this be that much better than a standard launch?
> You gain 28 miles in vertical ascent, but you're not
> moving at all, you still have to get up to around 7km/s
> for orbital velocity, so you shouldn't be saving that much in
> terms of energy expended to reach orbit: but you're adding
> complexity in terms of needing good weather, good wind
> prediction, a release mechanism that absolutely won't fail
> (I'd hate to see what happens if it does and you have to
> launch *through* the balloon) and probably half-a-dozen other
> things too, like cold-starting an engine 28 miles up!

The are some rocket efficiency advantages to this approach; & of course you
significantly reduce the negative impact of friction by launching from
50+kms; this is why many amateur rocketeers aiming for height records use
the approach; & some of the big agencies - including NASA & the DLR - are
studying the concept. I doubt, thought, that our high altitude
balloon/rocket technology has reached the point where it was really feasible
to even consider using the approach at this stage, though.

> I'd personally prefer to see something like the DC-X project
> restarted and funded as an X-project properly, and to see the
> aerospike engine used "in anger". Or did I miss something
> from the SR-71 test they ran with it? Even in 1965 the
> numbers said that SSTO was the cheapest way to orbit with
> chemical rockets.

The SSTO numbers are theoretical based on technological capacity which even
now doesn't really exist; & as i recall, never integrated developmental
costs into the equation, giving a very distorted picture of the real numbers
which advocates have been trying - & failing - to match in the real world
ever since. A largely or fully resusable two-stage-to-orbit is probably the
current best bet; but that assessment assumes that the technology
development costs isn't disproportionate to the market - an awkward
financial fact which buried Kistler's intriguing concept amongst others.

Frankly, though, the DC-X project was basically a technological joke with
only one real value for space development (its low-cost mission
administration; which may or may not have been scalable to a plausible
flight vehicle). There are WWI biplanes still around with better flight
characteristics than the DC-X; & the high-risk active descent mode is
generally not considered a plausible way of bringing real craft down from
orbit... for reasons the ultimate fate of the DC-X rather eloquently
demonstrated.

Live in peace
Robert.Clements@...
endeavour2 project http://www.geocities.com/robtclements/endeavour2.html>