A civil-registered R-5 at Kastrup, Copenhagen, in 1934.

An Aeroflot R-5 (P-5) at Khorog in the Pamir mountains of Tadzhikistan.

The P-5bis conversion of the R-5, in this case Aeroflot's SSSR-L3816.

Yet another variant of the Polikarpov PO-2 (NATO: "Mule") utility two/three-seat biplane, this time used by the Polish Red Cross. Note M-11 radial's Townend ring, also cabin-type fuselage.

A U-2S2 ambulance - SSSR-K82.

The simple “shove him in a box” U-2 (Po-2) in wartime use.

An AIR-6 (Ya-6) with M-11 engine.

The KhAI-1 fairly closely resembled the Lockheed Orion. Production totalled 43.