I changed the prop. The previous prop I balanced by grinding off the tip. The prop was statically balanced but not dynamically balanced which caused the
foaming. We flew friday with the filter clunk and had a few bubbles on first run up but none on subsequent run ups. On landing I hit the outer plastic barrier
and knocked off the tail skid ( Sky Raider Mach I - hi wing ). I was told that this was a weak spot with the Sky Raider and you should just leave it off. I bought
some Dubro wind skids and will put one on the rear to protect the covering.