"Bob Kuykendall" wrote in message
ups.com...
Earlier, Bruce Hoult wrote:
snip----
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.


Sealing a conventional canopy would be difficult but there might be another
way. Gary Sutherland's MOBA
(http://esoaring.com/pastarticleprojects.htm#moba) has a cockpit that opens
with the entire forward fuselage shell sliking forward relative to the seat
and the rest of the fuselage. That design could use a simple O-ring at the
separation line. Once properly sealed, the energy required to maintain
pressuration isn't too bad.

Bill Daniels