ORIGINAL: flaminheli
I personally love just the sound of the engine, especially a big gasser or radial. Try to shoot it when there is no wind so you don't hear all of the wind noise.
If you view my videos I do for my reviews you will notice that I do put down a low music soundtrack. I do this to mask wind sounds and the sounds of my breathing on tape. Unfortunately with the position of the microphone on my camera it picks up my breathing a lot of the time. So I put down a music track to cover that up. However, I lower the volume of that so that people can still hear the engine sound of the plane in flight.
Ken