Earlier, Bruce Hoult wrote:

So what is the pressurized metal sailplane hanging in the Museum of
Flight at "Boeing Field" in Seattle?

As others point out, it's Bob Lamson's Alcor. It's actually not metal,
but rather fiberglass and wood. Weise's book has a lot of great info on
Alcor's history.

The Alcor itself is a pretty fascinating ship. It's one of those
testaments to dedication and ingenuity that find their way into
forgotten corners of museums. it's sort of sad to see it hoisted way
out of sight.

Tony Burton flew Alcor in Canada to explore the climatology of the
Chinook Arch that often spans Calgary. He came down to the Tehachapi
SHA convention several years ago and gave a presentation on the Chinook
project. He'll tell you that he was chosen on the basis of fitting into
Alcor's undersized cockpit, but it's clear from the book and also his
presentation that he's also a damn good pilot and engineer.

If I recall correctly, Alcor's pressurization system is based on an A14
oxygen system in which the mask valves are turned around; the pilot
breathes in oxygen-rich air from the cabin and exhales overboard
through the hose. The cockpit was originally designed around a fairly
small pilot, but apparently turned out even smaller than intended, so
they actually stretched the cockpit laterally after the fuselage was
finished. But even so, it's said to be a tight fit for anyone over
about 5ft7".

I believe that the weak link in the Alcor's pressurization system was
the canopy seal; I think that the Chinook engineers never got it
working and so the Chinook flights were all unpressurized. That's sort
of as you'd expect; even with a pressure differential of only 3" of
mercury (about 1.5 psi) the separation force on the canopy is going to
be several hundred pounds, and it's hard to achieve a good seal under
the distortion you get from the pressure differential. Add to that the
distortion caused by the different thermal characteristics of the
various materials, and it becomes a very tough problem indeed.

Thanks, and best regards to all

Bob K.