Re: Reasonable Space Vehicle

From: Tom Kalvelage (tomkalvelage_at_sio.midco.net)
Date: 09/06/04 

To: sci-space-tech@moderators.isc.org
Date:  5 Sep 2004 18:37:39 -0700

Thanks, everybody! I don't think I'm getting all the posts (I
certainly can't see my original post), but here's my thoughts on those
who I did see.

On previous implementations of the reusable TSTO idea:
The nearest almost-flight example is SpaceX's Falcon, I think,
although it only reuses the first stage and that by parachute. Bob
Truax's various two stage boosters are the earliest design example I
can think of. There is a web-only fiction story (The Rocket Company
by Patrick J. G. Stiennon & David M. Hoerr) that is very similar.

On Kistler Aerospace:
It's not obvious that their first stage will land on land, or anywhere
near the launch site, based on their site. They do show a picture of
the second stage on land. They also use parachutes and airbags, not
propulsion, to land. It is close, thanks for the tip.

On idling the engines during reentry:
I've heard of this idea, too. I picked hatches because they are known
technology, and we have already bought into the risks (if the Shuttle
landing gear doors don't open, it's a problem). If the US had a
program to try out near-term reentry technology or operations this
engine-idle technique would be high on the list. A small TSTO like
the one I mentioned, with a very small payload, could be used for this
sort of technology exploration, and only risk the second stage.

On NASA doing the Moon, but not this TSTO idea.
I agree that NASA won't do this, but I don't think it has anything to
do with the Moon and CEV. NASA had Congressional consensus and over
$4B to do launch technology (SLI), and didn't do a launch program like
‘my' idea, the DC-X, or even Saturn-I (the X-37 looked at on-orbit ops
and reentry, not launch). So they don't appear to be looking at
launch testbeds, even in the best of situations.

On <20% of fuel spent on horizontal velocity:
That something like <20% of the energy goes into the horizontal
component of velocity is a good point. My spread*** model showed
the first stage provided something like 22% of the delta V, if I redo
it to about 15%, the first stage is a smaller fraction of the vehicle
(down from 72% to 55% of total mass), and results in a 10% smaller
payload. Just for grins, my model assumes the BDB first stage is 26%
structure and the SSTO second is 12% (not counting payload), which
should be beatable in the real world. This was worth my post by
itself. Thanks!

On the flyback booster:
By doing land propulsive VTVL I was hoping to keep the number of types
of staff that have to be paid to a minimum, and total costs down. The
vehicle takes off from land using rocket engines; since you need those
folks for take off, you might as well use them for landing. If you
add parachutes and put it into the water, you need those types of
people and engineering. If you use wings, you have to bring in
aeronautical engineers and technicians for the wings, aerodynamics,
landing gear, engines, APUs, and so on, and that's expensive (not that
it shouldn't be looked at, too). Truax addressed this by both taking
off and landing in the water.

Thanks again!

Quantcast