This morning I flew my propane powered airplane for the first time.

I have seen full-size powered paragliders powered with propane, but I have not seen anyone else fly a piston engine R/C plane on propane. I think this is a first!

I converted a new 40cc Briggs to R/C, then adapted a Lehr propane carb and regulator. (I had converted a Lehr 24cc engine first, but it had no power, so I moved the carb to this engine.) Power is moderate, 7000 rpm on 18x6 for a static thrust of 14.5 pounds. (20x8 yielded only 5300 rpm) A standard 14oz propane cylinder resides in the fuselage area normally used to house an expansion exhaust. It can be swapped out in a couple of minutes, and can be refilled at home.

The airframe is a 30% Yak that came up for sale cheap. (I hope to build more of a "floaty" airframe for this engine someday.) The all up weight of the Yak is 19 pounds 8 ounces. Take offs look just like the Spirit of St Louis, but it does fly! The engine starts easily, and runs reliably. With propane, throttle response is instantaneous.

The purpose of this exercise was merely to see if I could make it work!