Ursinus Leichtmotorenbau of Frankfurt manufactured small, opposed-twin-cylinder aircraft engines giving 21 hp at 2,500 rpm in 1927, known as the U-2 model, and the 15 hp U-1.

“Ursinus U-1”

“Ursinus U-2”

Both engines were for motor-gliders. See pressure gauges.

From Appendix 12: Two drawings of the Ursinus twin-cylinder engine (U.1). One of the engine itself, and the other as installed on an airplane.

“Two drawings of the Ursinus U-1"