PropSpinner, After using an OS .61 FX for the last six months I couldn't fathom using anything less powerful or dependable. I had a ST .51 on more than one Twist and although it could hold a steady hover...it would never have the thrust to play on the deck in even moderate winds. The .61 can recover in its own length 4ft off the ground! Now I'm not saying that any other engine won't fly the Twist around, but what I am saying is that once you try it you'll never go back to anything smaller. I've witnessed Jack's .82 Saito on his Twist and it is special in its own way, but it doesn't have the throttle responsiveness that the .61 does. To date I've watched Twists fly with .40,.45,.50,.51,.82 4s, and .61 mounted on their noses and I can say without reservation that this combo is something very special to me. Each engine mentioned above will fly the Twist, but the OS.61 FX can turn it into a magical bird! I just received the video from the other weekend and as soon as my son edits it for me I'll post it for everyone to see what I've been up on my soapbox hollering about! Throttle responsiveness is the key, without question...if you're big into 3D. I use an inch and a half Dubro heavy duty servo arm and I can pogo my plane just a few feet off the deck.

Peace,
Downtrodden.