Among the novelties of the 1922 Paris Air Show was a small two-stroke rotary engine designed by Paul Petit.

“Petit 2-stroke engine cross-section”

-Analyzing the shape of the piston, we observe that it has an upper “skirt” with ports and which is also inserted into a long cylinder head.

-According to the information that accompanies this illustration, the intention was to save the complicated and fragile system of piston head valves that radial rotary engines had at that time.

-This also saves weight with the two-stroke cycle and gains in simplicity.