This is similar to another post just made regarding a Pitts Bipe. My Reactor bipe has the similar problem- I require a dle20 to balance it, not the FS110 I am using, so i am guessing the weight difference is nearly a 150grams. With the 110 it balances at or just after the rearmost mark of the CG range given. Really, how do you get these to balance?


Also, my bipe seems much heavier for the size. Its 48" span and weighs 3.6-3.7kgs dry. Its got total 1100sq.in wing area as per GP, but I am not sure how that helps if its split up into two wings. Is it just me or is it really overweight?

Ameyam

I can't help you with calculating the CG thing, but I can tell you that on bipes, you do use the combined wing area with the weight to get wing loading. Your numbers would indicate the wing loading on that plane is not excessive at all. That thing should fly great with either engine?

I can also share that the CG listed on the plans of most planes (anything I've ever been involved with, especially GP!) is VERY conservative. Generally being well forward of where an experienced flyer might end up when messing with it. Based on that, what you're describing is something I wouldn't hesitate to fly at all? -Al

Yes but this is my first bipe and I cant risk it porpoising and being uncontrollable. Thanks for the infor though

Ameyam

remember, use leverage to your advantage... add weight as far FORWARD as you possibly can... (heavy washers behind the (weighted) prop nut)
if there is any chance of lightening the tail, do so (without compromising the structure... lighter hardware, etc, every little bit helps)
also if at all possible, try mounting the lighter engine as far forward as you can get it....
Move the battery as far forward as you can.
get the CG where it was with the heavier engine and fly it.
you can then work on removing some weight little by little.
at the end of the day, ~ 6 ounces is certainly not unheard of