Re: How Rockets Differ From Jets


Brad Guth wrote:
> >tomcat; Two things really impress me about basalt fabric:
> >it's insulative properties and it's psi.
>
> That's but two good points. Here's a few more;
>
> 3) it's thermal range isn't anything to sneeze at.
>
> 4) it can be made into large(cm3), medium(0.1 cm3), small(1 mm3), sub
> mm3 sizes and even nearly micro sized spheres of less than 0.001 mm
> balloons that'll can contain just about anything from a vacuum to good
> old and 100% safe H2.
>
> 5) it's rock cheap, and as such can be found just about anywhere,
> including upon the moon.
>
> 6) did I mention being essentially fire-proof and non-toxic, at least
> up to the point of melting.
>
> 7) it offers damn low density potential, as it can get down to less
> than 1 kg/m3 if need be.
>
> If the outer skin of the shuttle were of a basalt composite (which
> could also include titanium or tungsten fibers), chances are fairly
> good that if unprotected it would have been badly damaged but otherwise
> a whole lot more survivable for the crew, especially if there was a
> reasonable thickness and subsequent degree of R-factor involved.


Aluminum, which the Shuttle has for it's inner skin, is a very bad
material for anything that has to undergo the blast furnace
temperatures of hypersonic flight.

Most metals are meltable and flexible, two poor properties for a
waverider's skin. Ceramics can take the heat. Composite can be made
very stiff and strong.

Since ceramics are brittle and they must form the outer portion of the
skin, stiffness and strength are very important for the inner skin, to
prevent skin flexing. It also means that the internal ribs and
backbone of the spaceplane must be very strong as well.

Both CNT and basalt fabrics meet these needs. CNT falls a little short
on the thermal conductivity scale. While 'thermal conductivity' is
great for moving heat from the leading edges and forming the hull into
a heatsink, it is bad for stopping heat flow into the ship itself.

Best then, for the outer hull, would be a layer of basalt fabric,
followed by several layers of CNT/basalt composite, finished off by a
layer of CNT. Then, on top of that, Corelle/silica tile composite
ceramic clamped and cemented to the skin.

The binder should, in all cases, be graphite epoxy because it is stiff
and can take the heat.

The internal ribs and backbone could be hollow titanium tubes laminated
with basalt fabric. Again, the use of graphite and/or boron epoxy
would add the necessary stiffness and heat resistance.


tomcat

.

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