Back in November 2019 I bought this high wing Sonic from https://towerhobbies.com (item PMMA1125). The model aircraft came with the option to use electric or gas and I went with a O.S. .25 glow fuel engine that a friend donated to the project.

The kit went together easy and fast. The .25 glow fuel engine with a 9x5 prop ran it pretty good but needed quite a bit of runway to get it in the air. The plans actually recommended a .35 glow fuel or a Rimfire 32 electric so we knew in advance it was under powered. 


It needed more power to launch quicker and tackle them breezy days. An O.S. .46 LA came along at a good price, pic above with the 11x6 Masterairscrew prop.

The upgrade made a noticeable difference with launch, landing and aerobatic performance. It won't do unlimited vertical but gets way up there now. The .25 needed over 2 ounces of lead and the .46 made it possible to remove all that lead and give it a "little nose heavy" ....perfect!
Timber