RE: yak 54 (50)
If you're thinking of buying one....go ahead. A buddy at my flying field has the Extreme Flight .60 size with a YS 110 installed. It goes into a wall then instantly into a hover and sits there 10 feet over the middle of the flying field for 5 minutes...then pulls out vertical. It's the most amazing thing I've seen with this plane...but it also does all the other stunts.
Cheers.