RE: Balancing low-wing plane
 

Just read your powt #20. That makes the most sence to me. thx.

RE: Balancing low-wing plane
 

Another thing occurs to me. What about wings that are not constant cord? Where is the CG at the wing tip? If the LE is straight, I suspect that it would not change, but a swept wing would change, would it not? What do you think?

RE: Balancing low-wing plane
 

.... or screw an eyebolt in on the CG if possible, upside down if it is a low wing.

Ernie

RE: Balancing low-wing plane
 

garcay, There is a formula for figuring out where a wing should balance.

RE: Balancing low-wing plane
 

excellent, thank you!! I am an architect and in structural enginnering we refer to this as the geometric center of a given area. Or so it would appear.

RE: Balancing low-wing plane
 

Now, I have one for a good argument that is controversial in nature. Measuring the CG with the Retracts Down or in up positions ?

I have seen many argue the point to death.

What do you all think ?


In my knowledge, gear down and locked. The A/C is most unstable at the time of low speed and dirty on take off and landing. It's my understanding also, the real aircraft are also cg checked in down and locked configs.

Comments please :)

RE: Balancing low-wing plane
 

It depends on how much drag you get from the gear and if the gear retract parallel or perpendicular to the leading edge. Parallel gear will have little effect, perpendicular might if your wheels are heavy. If you balance with the gear down you'll fly slightly tail heavy with the gear up. That's becasue he wheels will swing from in front of the CG to behind the CG. I always balance only slightly nose heavy to eliminate any doubt. That's just me.

RE: Balancing low-wing plane
 

If you want to avoid nasty surprises, always balance the airplane in it's most tailheavy configuration. You should be able to figure out which configuration that is for your airplane. Since nosewheels usually retract rearward and taildragger mains are usually raked forward when extended, most airplanes will be more tailheavy with the gear up.

Jim

RE: Balancing low-wing plane
 

OK I figured I'ld include my version of a plane balancer, all you need is a 2x6, a couple un sharpened pencils, and to drill a couple holes.
But now I have a question. I just finished putting the plane in the pics together and checked the balance. The instructions say that it should balance anywhere from 3.75" to 4.33" back from the leading edge. Mine balances right at the front mark of 3.75". After the first flight yesterday, it seemed like it wasnt real steady flying, controls were sensitive, wouldn't level itself out. I've heard that if the planes balanced to far forward or rearward, that it will not fly very good. Can someone please tell us how this works. ie .. balance toward the front mark and it's more stable, or towards the rear mark and its more stable???? I always tryed to balance other planes in the middle of the 2 marks, but this plane is perfect without no weight at the front mark, so I left it alone.

NOTE: This is my first aerobatic plane, have had high wings before this. How will this plane handle differently then the high wings??

Thanks.

RE: Balancing low-wing plane
 

Ok, first off, balance towards the front of the range means it's on the nose heavy side, so it will be more stable - toward the back means it's on the tail heavy side, so it will be more sensitive.

Regardless of where you have it balanced, you will find a CAP to be EXTREMELY sensitive compared to most High Wing planes

RE: Balancing low-wing plane
 

Airplanes with a symmetrical airfoil and a low wing like your CAP are not self leveling like a high wing. They will go exactly where you point them and if you let go of the sticks the airplane will follow it's present course all the way to the ground. That is why they are good aerobatic airplanes; they do exactly what the pilot commands and nothing the pilot didn't command. If you are looking for high-wing-like stability in a CAP, you won't find it.

Still, you should be able to get comfortable with the way the CAP flies. The first thing you should do is reduce the elevator throw by 50%. You may also want to reduce the aileron throw. That will make the airplane much more docile. As you get used to the plane you can increase them again. Leave the CG at the front of the range for now. Moving it back will make the elevator more sensitive.

Jim

RE: Balancing low-wing plane
 

Mike and Jim,
Thanks for your input, it helps alot. I will leave the plane balanced like it is. The first thing I did when I got back from flying it was to reduce the throws on the elevator and rudder. The ailerons only have 3/8" throw to begin with, so I think they are fine. I guess it will just take some flying to get used to it, and I hope I get plenty of flying on it. :D Have a good one.

RE: Balancing low-wing plane
 

Make sure on a symetrical wing that the ailerons are centered also. If they both droop a bit for example, the plane might hunt or hop at high speeds.

Ernie