Long retired now, by far the most satisfying time of my entire professional career as an aerospace structural engineer occurred from 1959 through 1963 while working on the XB-70 program at North American Aviation, Inc. It was a time when I’d get up on a Saturday morning (day off) and head in to work just for joy of it and work in relative solitude. My work was mostly in the crew compartment where the airframe used both high strength steel and titanium alloys because of the high temperatures (450F) involved at Mach 3. Aluminum was incapable of withstanding that much heat and was used sparingly in the interiors where the pilots were able to function in a shirt-sleeve environment. The key to that thermal gradient was use of a “transpirational wall” (thin sheet with tiny perforations) that covered the inboard chords of the frames. Much testing was necessary for the design of the jettisonable escape hatches above the pilots who were seated in capsules-on-rails that would seal them in (along with their environment) just prior to jettison via self-contained rocket. Ejection sequences, programmed, took place automatically once selected; pilot and co-pilot could eject separately if necessary. This system was designed for ejection at Mach 3 and 70,000 ft. After the capsules cleared the aircraft, telescoping booms would extend to stabilize the capsules from tumbling until the parachutes opened. Each capsule had in inflatable bag on its bottom to cushion the impact of a landing on terra firma or for flotation during a water landing. It was June 8, 1966 when I was participating in an Ansel Adams workshop in Yosemite that I was shocked to read the headline that the second of the two prototype airplanes suffered a mid-air collision with a chase plane and crashed on the desert floor during a slow-speed photo-op flight. I remember that day as if it happened just yesterday. The pilot was able to eject safely and survived – a harrowing experience as related in an interview to Time Magazine – but he was unable, due to the lateral G’s from the flat spin, to pull the co-pilot back into his capsule so he could eject him and he perished with the plane. Very, very sad.
For those interested, here is a relatively superficial story of the development of the airplane and the aftermath, with lots of pictures.
http://unrealaircraft.com/classics/xb70.php
Bookmarks