Originally Posted by GorillaToast

Ok!

I maidened the rebuilt Yak this morning. CG was workable, but I had other issues. First was the tendency for it to roll right constantly. Even adding 10 clicks of L Aileron didn't help. I had to keep inputting L Ail to fly level. I'll recheck the wing / stab incidences and adjust if necessary before next flight. I'll also check the lateral balance.

Second issue was the tendency to continue rising at cruise throttle. Could be related to the 1* of stab incidence or I need to add 1* of down thrust. I'll try adjusting the stabs first, although they don't have adjusters. I'll have to elongate the anti-rotation pin holes to do that.

Thirdly was a motor case temp issue. In ground testing, I had to limit the throttle to 75% to keep the case temp below the recommend 65*C max. Ok, doable, but on a 20.5 x 12W APC prop I wasn't able to get much vertical. I switched to a 20 x 15 (which is the Himax 6330 Pro recommended prop), let the throttle go to 90% and was able to do a half reverse cuban at full throttle, but I'm guessing the case temp had to be over the max at that point. I landed and taxied over to my station and immediately checked the temp with an infrared gun and it read 47*C. Knowing how quickly the temp returns to 47* from 60* in bench testing, I'm guessing I was near the max.

Both of those props show overlimits on wattage and temp in propCalc, but a 20 x 10 does not. Just wondering if it would have enough thrust for precision aerobatics. I'll have to order one and see. I know that propCalc gives all kinds of thrust data, but I haven't studied about that enough to have it mean anything practical to me. Like how do I know what static thrust, stall thrust, specific thrust numbers are necessary for my Yak to do a decent vertical for a hammerhead?

Anyway, any opinions welcomed.
Thanks

Edited for: spelling / puncuation