Xref: utzoo rec.aviation:12855 sci.space.shuttle:2527
Newsgroups: rec.aviation,sci.space.shuttle
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: SR71 to be retired October 1st.
Message-ID: <1989Mar13.172841.1014@utzoo.uucp>
Organization: U of Toronto Zoology
References: <1659@trantor.harris-atd.com> <5527@cognos.UUCP>
Date: Mon, 13 Mar 89 17:28:41 GMT

In article <5527@cognos.UUCP> roberts@cognos.UUCP (Robert Stanley) writes:
>However, one of the reasons that Boeing put forward their SST proposal was
>surely because they had exactly the experience that was needed.  The XB-70
>(Valkyrie) was the pioneer in this respect, and didn't it make extensive
>use of epoxy-bonded, honey-comb titanium sandwich?

The XB-70 used brazed stainless-steel honeycomb sandwich, actually, with
some titanium in the forward fuselage.  It was built by North American, 
incidentally, not Boeing, although some of the technology may have been
common property.

>In the same time-frame, Lockheed built the A11 (where this thread
>started!) with Titanium as the primary skin material...

A-12, please.  "A-11" was another of LBJ's verbal typos.

>... As an aside, I believe that stainless
>steel has always suffered from being too dense, and that is what has
>excluded it from consideration, rather than the difficulty of working the
>material.

Stainless steel *is* heavy, although it's been successfully used in some
experimental aircraft (notably the X-15).  The stainless-steel honeycomb
sandwich panels used in the XB-70 would be ideal for high-speed aircraft,
as they are light, they are strong and rigid at high temperatures, and
incidentally they are moderately good thermal insulators, but they are
*horrendously* expensive.  The cost of the first XB-70 exceeded the
aircraft's weight in gold, and this was a half-million-pound aircraft.
-- 
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