Horrendous Catastrophe During Demonstration Flight

This is the Boeing 307 Stratoliner:

"The maiden flight of the first Boeing 307 Stratoliner (not a prototype, as it was planned to be delivered to Pan Am following testing and certification), registration NX 19901 took place from Boeing Field, Seattle on December 31, 1938.[8]

This aircraft crashed on March 18, 1939, while being demonstrated to representatives of KLM. After takeoff the aircraft climbed to an altitude of 11,000 feet. At this altitude, longitudinal stability tests were made. The next tests, as outlined by the flight plan, were side-slip tests. The aircraft went into an inadvertent spin subsequent to a stall at an altitude of approximately 11,000 feet. It made two to three turns in the spin, during which the engines were used to aid recovery. In recovering from the dive subsequent to the spin, the wings and horizontal tail surfaces failed upward apparently due to air loads in excess of those for which the aircraft was designed. The ten people aboard, including the KLM technical director, a representative of the Dutch Air Ministry, a Boeing test pilot, the Boeing Chief Aerodynamicist, the Boeing Chief Engineer, and a TWA representative were killed.[9][10] Subsequent wind tunnel testing showed that the addition of an extended dorsal fin ahead of and attached to the vertical tail prevented rudder lock. The redesigned vertical tail and fin were tested on NC 19903.[11] This was incorporated into the 307's rudder redesign, while also being incorporated in Boeing's rear fuselage redesign for their models "E" through "G" B-17 bomber."

Don't see how it could get any worse. And what does it mean for wings to fail upward?

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Reply to
Fred Bloggs
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I'd assume that - rather than being more or less flat - they 'd have bent in the middle into a V-shape. Spin recovery does seem to involve putting the spinning aircraft into a dive, which apparently meant that it ended up going faster than the airframe had been designed to cope with. Lift goes up as the square of the velocity through the air, so they presumably ended up with a bigger bending moment along the length of the wing than the wing spars could cope with.

Nasty, but that's why test pilots get paid a lot and end up dead from time to time.

Reply to
Anthony William Sloman

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Reply to
Edward Hernandez

We are always grateful for your morning cheer.

Reply to
jlarkin

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Reply to
Edward Hernandez

The John Doe troll stated the following in message-id <sdhn7c$pkp$ snipped-for-privacy@dont-email.me:

And the John Doe troll stated the following in message-id <sg3kr7$qt5$ snipped-for-privacy@dont-email.me:

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Reply to
Edward Hernandez

...

I suspect it meant the wings folded/collapsed upwards...not much to do with electronic design though.

John

Reply to
John Robertson

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