W. Rupert Turnbull was a Canadian aviation pioneer, and under his direction, Duryea in ​​the USA developed the engines he used.

-In 1905, he made a prototype. It was a horizontally-opposed twin-cylinder that gave 2 HP at 1,200 rpm.

-Later, a 16 HP, 4-stroke engine was developed, water-cooled, with automatically opening intake valves and mechanically operated exhaust valves, without a central crankcase or exhaust pipes.

-It was installed on Turnbull's hydroplanes. The result is unknown.