In article ,
(The Enlightenment) wrote:

No. You don't understand creep strength. The rate of creep is not
such that it should deform significanty and as I point out Sanger's
silver bird re-enetered at far less than orbital velocity.

I understand it quite well, thank you, the problem is that you're
severely underestimating both the heat and stress on the Silverbird (as
I've pointed out about a half-dozen times so far).

All hypersonic aircraft, like the SR71 irrespective of material don't
have fatique problems becuase the heat effectively heat treates
(aneals) any work hardening metal. Titanium, inconel, austenitic
steels all are the same.

The problem isn't long term fatigue, it's short term falling apart
because it gets really bloody hot in a very short period of time. The
high wing loading of the Silverbird would just make things worse, and
comparing it to an SR-71 (made out of tougher alloys) that flew about
1/4 the speed is just sad.

Duh, Stainless steel IS a high temperatue alloy.

The one you quoted as your first example (boiler-type stainless) is
*not*, in this case high-temp enough, by about 600 or 700 degrees.

There were several German companies around at the time that could
produce high temperature refractory alloys and sold them commercialy.

....and that might have been enough, if the plans had called for
high-temp alloys. They did not, as you've been ignoring. PLain old
stainless.

He did Hypersonic wind tunnel testing.

...on tiny little models of the Silverbird, for less than 30 seconds at
a time, with *no* heat testing, and could not have done any different
with the equipment he had during the war.

Thirty seconds (even 30 milliseconds) is plenty of time to get L/D
ratio data, stability data, center of pressure data and to use
Schlierian photography to image shock waves and to place a few
thermocouples in the model.

Except that, as photographs of the models have shown (readily available
on the net and in books), there was no place *on* the model to place
thermocouples. They did *not*, again, do this. You can keep hoping
they did, but it's just plain not so. They got the gross aerodynamic
data, but not the sort of detailed stuff they'd need for a successful
program.

You assume NASA tested the shuttle near full scale at hypersonic
speeds.

No, but they tested smaller scale models at hypersonic speeds in all of
the ways that Sanger did *not*, and they had a couple of decades of
practical experimental data (X-15, SR-71, Apollo) on high-speed flight
and reentry.

Clearly the Silver bird concept allowed incremental testing and
development at progressively higher speeds. In many ways it was a
highly testable designe. Everything from sled acceleration, Sled
seperation, and rocket motor lightup at progressively higher speeds.

....and given a decade or so, Sanger might have had a chance to fill in
all of the blanks he didn't do in his first attempt. The Silverbird
was, again, a nifty idea with very little engineering data behind it,
like so many of the German "superweapons" that were never built.

--
cirby at cfl.rr.com

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Slam on brakes accordingly.