Balancing technique.

[Perry Rose]

 I deceided to recheck the balance on all my fleet and kept wondering how is the best way to set the plane on a two pin balancer, up right or inverted. Upright is real touchy and inverted is more stable on low wing planes. Does it really matter as long as the end result is correct? Should I check them both ways?

[Busby]

It should make no difference although it could indicate that your vertical CG is off.
Busby

[Leo Mehl]

It should make no difference although it could indicate that your vertical CG is off.
Busby

I don't think it makes a lot of difference but I do the final balancing when i get the plane in the air and that is one of the trim issues when trimming. I like my plane to turn with just a little pressure on the handle. Some like it more on the nose heavy side. I have always found that if you built the plane strait it will still fly good a little on the tail heavy side.

[Larry Fulwider]

Or you can get Vanessa to help

Larry Fulwider

[Glenn (Gravitywell) Reach]

I'll bite....what the heck kind of Rube Goldberg gadget is that!?

[Dave Rountree]

glen it is a devise to find center of gravity. Hanging from the dowel rod is a plumb bob, which points directly to cg. Rotate the dowel rod until the wing is level( incidence meter is you want to get scientific about it), plumb bob will hang at cg. add weight to the front or rear to get the plumb bob to hang at your cg preference. here is a link to get more info and diagram. http://www.manateerc.com/cgfixture.html                                                   
                                                                                                      Dave R

[Perry Rose]

Thanks Dave, I remember seeing and reading about that gadget years ago.

[Larry Fulwider]

. . .  Rotate the dowel rod until the wing is level( incidence meter is you want to get scientific about it), plumb bob will hang at cg.  . . .                                              
                                                                                                      Dave R

Dave --

Correct. Note in my pic, the little yellow thingie in front of the cockpit is a level. The level is a string guide leveler normally used for masonry work -- light. The trick on some airplanes is finding a place near the cg that is parallel to the wing 0 incidence line on which to put the level. On some planes I tape a shim to one end of the level so that it sits level at 0 incidence on the sloping top of the fuselage. Oddly, eyeballing level with the plane close to the floor is way more difficult than you would think. I eyeballed one, then checked the level, and found I was off by over a half inch at the nose!

I think the device is more useful as the plane matures than for for the initial setting. After the plane is trimmed to your satisfaction, bring it home and see where the CG actually ended up, and record that. If you change props (APCs, for example, are a lot heavier than wood props), spinners, wheels, tanks, or repairs, you can put the CG back where you liked it with absolute certainty. Also, if after several flights, you decide it is a bit too twitchy, or a bit too sluggish, make a field change, you can also record the new number for reference, go back to the previous number, or whatever.

Larry Fulwider