Re: Reentry shielding - was: should space shuttle be cancelled?

Pete Lynn wrote:
> "Len" <len@xxxxxxxxxxxxxx> wrote in message
> news:1123945874.509713.308740@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> >
> > Radiation from the bottom heat shields--plus our patented
> > TPS insulation--should get cope with nearly all of the heat
> > transfer within a thickness of perhaps 2 cm. The problem
> > is to keep a good temperature gradient across the lower
> > surface insulation. Prior to your suggestion, I guess I was
> > relying primarily on conduction into an internal heat sink,
> > rather than radiation and convection to the uninsulated
> > upper surface skin panels--which could then serve as
> > radiators. I thought about insulating the truss members;
> > however, this would be quite complex because of the
> > relatively intricate nature of the truss, which may be a
> >"truss of trusses" to achieve ultra-light quality. Like
> > composites, the superb stiffness of Be/Al/Mg allows the
> > truss structure and sandwich cell structure to "open up."
>
> I think I have finally figured out the reason why you mentioned that
> small scale hurts, (below around 80 ton GLOW for upper stage orbiter).
> Shielding, insulation and skin weight is relatively fixed - probably in
> excess of 10kg/m^2? This becomes prohibitive at smaller space transport
> scale. This got me to thinking, here is another one for you:
>
> A single metallic skin similar to a hang glider is possible for most of
> the wing area. This should be capable of L/D in the 10-15 range if
> necessary, which should be more than sufficient for this task. This
> eliminates the mass of the top skin and provides direct heat transfer to
> the top surface, the bottom surface could still be insulated. A leading
> edge tube or truss section would still require the double skin highly
> insulated more conventional approach. The trailing edge would require
> rounding or a similar double skin approach to avoid the heat
> concentrations there. Reinforced battens or ribs should also be fairly
> straight forward, perhaps acting as radiator fins on the back side of
> the wing - back of the leading edge tube? Such a single skin metallic
> wing might look something like a bat wing or yacht sail.
>
> My guess is that this approach might potentially reduce wing weight by
> as much as 50%, depending, though the primary advantage might be
> simplicity of construction. The single skin approach does seem to
> preclude composites, except in double skin areas where there can be an
> internal heat sink and lower internal temperatures, far more insulation
> would be required at these points. Wing spars, trusses, etcetera might
> also be largely locatable above the single skin, where they could be
> shielded from the direct heat of reentry. It might be possible to use a
> relatively simple lower surface insulation coating on the single skin,
> which might be a high temperature stainless steel, or nickel-alloy.
>
>
Let me say at the outset, that I think there are a number
of good ways to get to orbit a lot simpler, cheaper, more
reliably, and more frequently than what we are now doing.
It's just that the ways on which we have spent a lot of
money aren't very good.

For our very low planform reentry, the upper skin (back a
ways from the leading edge and excluding primary truss
structure) tends to be a lot lighter than the lower skin
plus insulation--perhaps as little as 1.2 kg/m^2--compared
to perhaps 5 kg/m^2 for the lower skin and insulation. As
for eliminating the insulation, the choice between hot
structure and insulated primary structure is, IMO, a push.
That was one of the primary differences between our 1971
Windjammer and the follow-on Boeing RASV. It seems to be
primarily a trade-off of different types of complexities.

Bottom line: I think you may have a good approach--as described
below. However, I expect it may be more complicated operationally,
without a significant increase in payload or cost-effectiveness.
But, as I mentioned, I think there are a number of ways to skin
CATS. I think we both agree that--after four-and-one-half decades,
we still haven't spent enough time and money on conceptual
approaches. And, by conceptual study, I mean addressing some
basic mission need as directed by OMB A-109--not some bureaucrat's
preconceived solution, often couched in a hidden agenda. The big
money has been spent on concepts that were never well thought out
in the first place. What little amount of conceptual exploration
money has been available has been wasted on preconceived solutions,
rather than wide-open studies that address specific mission needs.

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

> I had just come up with a nice tank layout, all reentry surfaces, except
> control surfaces, would be backed by a pressurised gas - active heat
> transfer and heat sink. Basically it would look like an inflatable
> boat, with the propellant tanks up the sides and around the nose. The
> cabin pressure vessel would be shaped to exactly fit within this "U"
> shaped tank, well protected. Control surfaces/wings at the back would
> add sufficient L/D and cross range control. The tanks are the
> structure, CoG management should be good and even water landings might
> be possible.
>
> I am now thinking it is better to reject the reentry heat directly
> rather than go to great lengths to insulate against it, absorbing the
> remainder into the internal structure. Using tanks as heat shields my
> result in a fluffier design with lower heat loadings, but their double
> skin nature also prevents one from re-radiating that heat away, it has
> to be absorbed.
>
> Pete.

.

Relevant Pages

  • Reentry shielding - was: should space shuttle be cancelled?
    ... > Radiation from the bottom heat shields--plus our patented ... > TPS insulation--should get cope with nearly all of the heat ... > surface insulation. ... > upper surface skin panels--which could then serve as ...
    (sci.space.policy)
  • Re: Light weight Euro-diesels
    ... > turn the skin of the aircraft into the heat sink. ... > You could end up with a deicing system instead of a radiator! ... De-ice takes a lot of heat to do a decent job. ... > there is not enough heat in the gas to thaw out a wing. ...
    (rec.aviation.homebuilt)
  • Re: Light weight Euro-diesels
    ... turn the skin of the aircraft into the heat sink. ... You could end up with a deicing system instead of a radiator! ... De-ice takes a lot of heat to do a decent job. ... there is not enough heat in the gas to thaw out a wing. ...
    (rec.aviation.homebuilt)
  • Re: Ping Morris
    ... insulation needn't be costly - and are certainly less costly in the long ... almost exclusively geared towards producing homes with walls and roofs ... whatever room temperature (any temperature you care to choose that might ... Physics help please - heat storage ". ...
    (rec.woodworking)
  • Re: New boiler installed System 2000
    ... What temp does the 2000 heat water to, does it vary with outside temp ... 1978 I've added attic insulation. ... The water goes to about 180. ... Unlike gas or oil fired, there is no stack for hot air to leak from. ...
    (alt.home.repair)
Quantcast