I was given a Great Planes Bonanza 15E as a present. Since I am not an EP flyer I converted it to GP with an OS25 FP for power. I beefed up the firewall and used standard servos, Futaba S148s, for the rudervators, throttle, and nose wheel. S33s were in the wing for the ailerons and flaps.

To make this story short, on the first day of flying, it took off and flew well straight and level. After a few passes I pulled up for a split "S" turn at the end of the approach. On the bottom of the loop (pulling max Gs) the plane snapped to the left violently and spun in straight down the remaining 50’ to its demise.

Did I over load the airframe? Or is this a symptom of a light EP design that was never meant to move that fast?

Any one else do an EP to GP with similar results?

[]

Sounds like an accelerated stall. Two things, either of which can cause this, aft CG or too much elevator throw. A combination of the two is even worse.

High speed stall usually is caused by a Forward CG condition and/or high wing loading,, A quick 3/4 snap when pulling elevator is the tale-tale sign that's what happened,, it would continue spinning unless you release the elevator.

The extra weight, coupled with the relatively small horizontal of that particular model could be the cause,, especially if it pushed your CG forward..

I was careful with the CG position, in fact I used a heaver battery pack as far forward as possible to get the CG in range. I never considered the smaller surface area of the V tail as a possible issue but that's why I am on this forum. I was pulling lots of elevator when it snapped. When it nosed over and was spinning I don't think I released the elevator. That's not a natural thing to do when the model is heading straight down so I did panic some. I just didn't have enough altitude to recover.

I just wonder if it would have done the same thing if I had set it up with EP power and pulled the same maneuver.

If all the conditions were the same,, then yes,,, what's making the prop spin wouldn't matter.

I had a Yak-9 Warbird racer once, with very heavy wing loading the plane has a relatively small tail,,,
If I pulled full elevator it would just snap to knife edge so fast it would make your head spin. Scariest plane I ever flew