A.G. Ufimtsev designed a rotary engine with 6 oscillating star-shaped cylinders supported by the cylinder heads, tilting a few degrees due to rigid pistons and connecting rods.

-Sometimes written as Ufimsev. This is the 100 hp ADU-4 model.

“Ufimtsev ADU-4”

“Copy of the Moscow Museum brochure”

-G. Ufimtsev's ADU-4 engine is currently on display at Hall 1 of the Monino Museum in Moscow and is listed as installed in “Spheroplan Machine No. 2.”

From Appendix 10: The main text states that the ADU-4 radial was installed on Spheroplan No. 2. Ufimtsev designed two aircraft for flight in 1910, numbered 1 and 2.

"Spheroplan nº 1 with rotating wings"

“Spheroplan nº 2”

-A.G. Ufimtsev designed his first birotary engine with two cylinders and a two-stroke cycle.

-One two-bladed propeller was firmly attached to the rotary engine, and the other propeller to the crankshaft. Both rotated in opposite directions. It produced 15-20 hp.

-The next engine was of similar architecture but produced 35-40 hp.

-As a characteristic, it had a compressed air starter supplied by a separate pressure cylinder.

-And in 1912, he built the 6-cylinder radial ADU-4. Manufactured at the Bryansk Plant.

-He also had a period in which he dedicated himself to manufacturing agricultural machinery.

From Appendix 12: We found another photograph of A.G. Ufimtsev's birotary radial engine, model ADU-4, at the Moscow Museum of Monino.

“ADU-4, Ufimtsev's birotary engine”

-The structure that encompasses the cylinder heads serves to hold them by the cylinder head as they oscillate with the movement of the rigid connecting rods and pistons.

This engine, built in 1912, was a six-cylinder, oscillating, birotary engine (the engine rotates in one direction and the propeller in the opposite direction). It produced between 65 and 70 hp.

The birotary design was intended to counteract the gyroscopic effect that made piloting difficult, thus neutralizing both gyroscopic rigidity and the so-called "gyroscopic precession" effect.

Precession has a very curious response: when a force is applied to the rotor support, the response is a 90° vectored movement. This means that if the pilot moved the bank lever to one side, the plane raised or lowered its nose, depending on which way it was going. See the "Rototo" chapter.