I once saw and heard a Mazda 20B 3 rotor motor. Whole motor minus intake and exhaust bits was smaller than a pony keg. Had well over 500hp in a 1900lb homebuilt, birdcage tube frame, two seater "sports" car. 12000rpms and smooth, I mean really smooth, with the most Gawd awful noise you can imagine, and flame out the straight pipes. However, like all roto's, it only took one overheat and it was toast, or more accurately, the various rotor housing and end/middle plate pieces of the engine sandwich looked kind of like potato chips instead of nice and flat and all sealed up. And there are 3 tips per rotor, and nine tips per engine, and I think I remember that the tip seals each have about 9 parts. That's 81 little finicky thingy dingys, each of which has to be installed just right, and you haven't even touched the edge seals yet, or the lobe seals either.

It's sort of like a good old piston engine Cessna 172, and a solid fuel rocket. The rocket is fast as stink, and makes a glorious smoke column all the way up to clean out of sight, and the sound of the engine is so loud it can kill you, but you can only fly it once. The old slow and ugly Cessna will fly, and fly, and fly, and fly.