I picked up a VT21 at a swap meet a couple of years a go, the chap never got it running because of the fuel line hook-up . I benched
it had in running in a few minutes it was quiet and good idle (and Bill it did have the aircraft head) In a moment of weakness I sold it
to a guy in the UK because I thought it did not have a lot of power for its size. It would have been perfect for a small cub or
similar and it was the Austrian version.At idle all you heard was the prop swish. One of the advantages of the diesel however is you can use a tank of half the size to get almost the same run time as a glow martin