On Thu, 08 Nov 2007 09:46:52 -0500, Dudley Henriques wrote:

Jay Honeck wrote:
I've just finished reading the tale of the first round trip coast-to-
coast flight (which was accomplished by mid-air refueling,
occasionally from milk cans) from Spokane, WA to the east coast and
back, way back in 1929.

Hmmmm....interesting definition of "coast to coast." Spokane is "on the coast"
the say way Pittsburgh is (e.g., hundreds of miles inland).

One of the pilots, Nick Mamer, went on to a career with Northwest Air
Lines. The author of the article states that he was killed in 1938
flying a Lockheed 14 Super Electra over Montana when the plane crashed
after suffering structural failure due to harmonic vibration. All
passengers and crew were killed.

Do a search for Lockheed Electra, Tell City Crash, 1960 I believe.
Reference that with propeller whirl mode, and you should come up with
all you'll ever need to know about resonant frequency as relates to
destructive force.

Wrong Electra, Dudley. Namer died in 1938 in the twin recip, twenty years
before the four-engine turboprop.

Wikipedia says, "Later, an investigation revealed that the tail structure had
failed on the new design from what is known as "natural resonance, or period of
vibration." Sounds like the natural frequency was too low....

Ron Wanttaja