RE: GSP Spitfire ARF build
Hello,
Noah, I have a Saito 100 in mine, which pulls this plane fine with an APC 14X8 prop. I think my max RPMs are around 9600 using Cool Power 15%. It does not have a lot of extra power on take off, but low passes at full throttle are spectacular! This engine is light (19.4 oz) and the slimline pitts muffler probably only adds a few ounces, so I am not surprised that I had to add a pound or so of lead to get it to balance while you didn't with your YS 120. I recently made some minor changes to remove weight from the tail, e.g., removing the antenna tube, etc., but added an on board glow driver. I was able to remove some lead from the nose, but given my last experience with the way it flew--with some tail heavy characteristics, want the cg more forward.
Noah, when you say yours balanced on the recommended cg, where was it? Are you planning on moving your cg? The manual states a range of 120-130mm from the leading edge and I now plan to balance mine towards the front end of that range, probably around 122mm. I recall that Richard L said his balanced in the middle of the range, presumably around 125mm, and that it flew fine there.
Travis