It was nicknamed the Flying Banana, but the Piasecki H-21 was no joke. With its distinctive shape and tandem rotors, this helicopter played a key role in military operations from Korea to Vietnam.

In eight months, the “flying egg beaters” plucked 1,700 ... is in the hands of young men and new companies: Piasecki Helicopter Corp. was founded by Frank Piasecki, 31, with four helpers ...