"Tom Sherman" <[email hidden]> wrote in message
"]news:[email hidden]...
Quoted message said:Dave Larrington said:If one is referring to the failure which caused numerous
Comet aircraft
to
Quoted message said:Quoted message said:crash in the 1950's, these were fatigue failures
propagating from the corners of the windows (which had
fairly sharp corners - bad idea) and /were/ due to p/d
cycles.
Only 2 or 3 of the Comet crashes were due to fatigue -
several other early crashes were due to excessive angle of
attack while attempting takeoff, and the remaining crashed
were due to pilot error.
However, fatigue failure would have eventually affected
most of all of the Comet 1 and 1A models if they had not
be retrofitted or scrapped.
Tom Sherman - Quad Cities (Illinois Side)
I was thinking that some of the early Vickers, (Viscounts?)
had a problem too but my brain turned to sawdust years ago
so I'll let others research that if they wish.
Aircraft builders did have experience with p/d cycles by the
time the Comet was built and other, piston powered, aircraft
had square corners which did not tear. Work hardening of the
aluminum skin from H.F. vibration combined with the
additional stress of higher altitudes and higher speeds
resulted in failures, often starting in corners, that
obviously were not expected from causes that were little
understood. Failure was occurring not only in sheet metal
but also in castings and machined aluminum parts.
Good thing those intelligent engineers figured it out
and fixed it or we might not even have an airline
industry today.
Jack
