RE: HP VT21 worth using?
Chuck:
The VT-21 is supposed to be a very nice running engine, but heavy for its power.
If you put it on a "Cub type" plane it should do well, but it's not going to be much more than a "Fly around the airpatch" engine.
Collectors? The last one I saw change hands was the VT49, the bigger version, and it went for $150.
You are aware the VT21 and VT49 atre both available brand new, made in the USA?
Bill.