3-4 years ago I put together the Abbra with a 40 cc ZDZ engine. I put together the same model using OS-160, YS-160 and Hacker C-50 since that time. Here is what I found:

1. Gas version was over 11 lbs about 4-5 oz. ES Carbon pipe with custom made soft mount. Initially the engine was hard mounted. The model was almost lost due to flutter in one aileron. The soft mount fixed the problem but added some more weight making practically impossible to get it under 11 lb. The OS model was a little below 10 lbs. The YS-160 was a little over 10 lbs and the electric is ~10.7 lbs.
2. Power. I could not do the Master schedule using the gas engine in the same way I was able to do with all other models. It was very difficult to make the upper radius due to lack of power (or additional weight). The gas engine could very well work for lower levels but I don't think is very practical for Master and F3A.

In conclusion, I tried and found that a gas engine is not feasible for pattern (higher classes). However, lower classes probably could do it but the additional work to find equipment could be a problem. I don't have anything against gas power. If fact I fly IMAC plane using 100 cc and I really like it.

Vicente "Vince" Bortone