Popular Science ( April 1933 )
That the speed of an airplane may be increased from thirty-nine to
140 percent by putting a ring around the propeller is the
discovery announced by two Compton, Calif., inventors.
The circular cowling is said to straighten out the air blast of
the propeller and increase its effectiveness.
Vanes within the ring, which the inventors are indicating in the
picture, may be adjusted during flight to increase the air drag
and so serve as brakes in landing.
US Patent 19611214
Aircraft Propeller Cowling
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