Repost: Len Cormier's Space Van 2008 (was Hydrogen peroxide helicopter)

My earlier responses on sci.space.tech seem to have vanished.

(James Graves) wrote in message ...
I found the Space Van 2008 proposal interesting. I had some
comments/questions:

What is the TPS? The slides imply they're not trying for a lifting
reentry. But a cheap, reliable throwaway heatshield isn't going to work
for that design, I don't think. Too much area to cover. Are we back to
RCC for the leading edges? We've all seen how well that works.

Like most of our designs, the TPS is an integrated design that
depends upon low-planform-loading, moderate-skin-temperature,
lifting reentry with metallic heat shields with a thin ceramic
coating--plus our patented insulation and heat sink to absorb
the 5 percent of heat flux that does not get radiated
(U.S. patent 4,919,366).

A very important part of the kite approach is the limitation
on peak dynamic pressrue. The orbiter never sees more than
2500 Pa anytime during the launch and reentry. This is
greatly relieving with respect to panel bending loads and
panel flutter--as well as overall aerodynamic bending and
other loads.

The orbiter is relatively small, with relatively thin wings;
accordingly, one approach is to sharpen the leading edges and
accept very localized higher heating. The density of the leading
edges is up, but the area is way down--with the result of an
acceptable penalty for leading edge mass. I have never advocated
throwaway heat shields--or throwaway anything--for a space transport.
Or any type of TPS requiring a lot of maintenance.

I think the 1st stage ascent engine(s) should be part of the gondola.
Is there any reason to carry them up to orbit and back? The attachment
between the orbiter and gondola has to take that kind of stress anyway.

This is an option. In fact, we are looking at a 1/20th scale
version called the "MicroVan" or "MiniVan." With scaling,
the orbiter tends to want to use all LOX/LH2--rather than a
tripropellant combination. Thus the kite/gondola is separaately
powered. (The payload goal for the MicroVan is 20 kg at very
low cost per flight).

For the full size vehicle, the AJ26 used for takeoff and climb
is just about right to continue the acceleration after separation
from the kite. This saves a restart; restarts are a significant
part of operational costs because of cycle fatique and eventual
need for a major overhaul. The assumption in the slide presentation
is series burn for the RL10A4-1 engines. However, parallel burn
may decrease gravity losses (essentially no more drag losses)
sufficiently to more than compensate for the extra LH2 tank mass.

A kite that size is going to be very unwieldly for ground handling.
I'm not sure what would be more practical. It might be easier to keep a
parafoil flat and not flopping around in the breeze than a more rigid
glider.

Ground handling is a legitimate worry. However, the kite
has a much better lift-to-drag ration than any parafoil
that I have considered. Peter Lynn Kite's "Arch" does hold
promise for a decent L/D.

Related to that...

The SV2008 is also more sensitive to wind conditions. This could cause
launch window problems. Ideally, you'd have a giant circle, with the
winch in the center, so that you could launch into the wind in any
direction.

That's the main drawback to a low wing loading. No easy way to escape
this, AFAICS.

True. But all launch systems have launch restrictions.
I don't look at the Space Van 2008 as being an ideal
"launch-on-demand" system. Rather, it is intended for
low cost transport of cargo and people--with an acceptable,
occasional launch delay.

Winds, and winds aloft, can delay ELV launches. I
understand also that one Atlas was lost to a lightning
strike when it was launched in high potential voltage
conditions that contra-indicated a safe launch.

James Graves

Best regards,
Len (Cormier)
PanAero, Inc.
(change x to len)
http://www.tour2space.com