Welch Aircraft Motors of Anderson, Indiana, developed a horizontally-opposed twin-cylinder engine around 1934, primarily for use in its own aircraft.

-Known as the O-2, it had a displacement of 135 cu in.

-It actually produced 41 hp at 2,300 rpm and 45 hp at 2,500 rpm.

-It was manufactured until 1941. It featured single ignition.

“Welch O-2”

-The Welch O-2 was designed by the company's president, general director, and owner, Orin Welch.