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| Torpedo test |
The United States Navy requested we test the effect of attaching two 500 pound torpedoes to the sides of a HUP helicopter. The weight was not a problem, however, after launching one torpedo the lateral center of gravity would be displaced by the one remaining torpedo.
It seemed like a simple test to be performed so the
aircraft was configured for the test. The pilot taxied to the end of the ramp area and attempted to
lift off to a hover. The aircraft
immediately rolled on its side, with rotor blades pieces flying in all
directions.
What Happened?
The test engineer, Chuck Vandusen elected to mount a
ballast box on the landing gear structure with proper weights installed to
simulate the 500 pound torpedo. The landing gear incorporates an oleo strut as
most heavy aircraft do. With this installation the weight was on the landing
gear and not the airframe.
The pilot could not detect the displaced center of
gravity as he slowly added power, but when the wheel came off the ground he
suddenly encountered a roll that he was not prepared for and could not
control. As a result the helicopter
crashed. No injuries, we repaired the helicopter, mounted the ballast box on
the airframe and successfully completed the test program.
From
thereafter Chuck was known as “Lateral Vandusen.”
Charles Kessler is a retired flight test engineer for
Boeing’s Vertol helicopter division (formerly Piasecki Helicopter Co.). He
joined Piesecki in 1947, in the company’s fourth year, and retired from Boeing
in 1983. During his 37-year career he took part in the testing of prototypes
and alterations of such models as the CH-47 Chinook and Sea Knight, the H-16,
HRP-2, and the V-107. He taught the stability augmentation system to the German
Luftwaffe. He has written about his experience in a blog called “Early
Helicopter Years,” which can be found at http://helicopterstory.blogspot.com/.
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