The HP VT21 4-stroke RC model plane engine
This is a 30 year-old 4-stroke engine which has an Aspin Rotary Valve in the head rather than more conventional poppet valves and camshaft.
These engines are very weak but also amazingly quiet.
The airframe is a very old design from the 1960s I think and it weighs a ton. Flying this engine/airframe combination requires a *very* light touch on the sticks because it'll stall in an instant if you attempt to slow it up or use just a fraction too much elevator.
Still, it makes a nice change from grossly overpowered trainers, 3D machines and pulsejet-powered RC models.
These engines are very weak but also amazingly quiet.
The airframe is a very old design from the 1960s I think and it weighs a ton. Flying this engine/airframe combination requires a *very* light touch on the sticks because it'll stall in an instant if you attempt to slow it up or use just a fraction too much elevator.
Still, it makes a nice change from grossly overpowered trainers, 3D machines and pulsejet-powered RC models.
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