I have more 4-strokes than 2-strokes in my hangar and I have to say that the 4-strokes sound like tractors.

There is no way they sound anything like a full-sized aircraft, and I should know, I work at a full-sized airfield most days.

The reason I have 4-strokes is because for the type of flying I prefer (3D) they have very real advantages over a 2-stroke (able to swing a larger prop, better spool-up and lighter per pound of thrust -- yes, that's true with Saitos).

I also have a 4-stroke in a P51 mustang and despite pushing it to 10,800 RPMs and running without a muffler, and despite it flying just as fast as a friend's 2-stroke-powered identical model, it's just not a scale sound.

In fact, his ST90-powered P51 sounds just insane with an MAS K-series prop with its tips sizzling and crackling as it does a low pass. I may pull the 4-stroke out of my P51 and put a 2-stroke in it -- much more realisitic.

However, the *most* realistic sounding planes are those powered by gas motors. A good 35%-45% model with a 100cc-150cc twin sounds *very* realistic (to me anyway).