I am wondering on how I go about adding weight when balancing for the CG and the wings. How do I add weight if I need to to the wings?

For the CG, I was just planning on measuring and drilling holes in a 2x4. Then insert pencils with the v tipped add on erasers to set the plane on and balance. Doing this for a 63" wingspan extra 300s.
1st plane I will be completing from start to finish. Just bought and flew RTF's till now.
So please shower me with your knowledge and tool reccomendations.

Adding weight to the wings? Don't bother, it won't make a bit of difference to the way any plane flies for you for a long time. IF your skills EVER rise to the level that wing weights matter, by then you will know.
As for weighting the fuselage, get some stick-on weights from your LHS and place then as FAR forward or aft as possible. It takes less weight that way.

why waste your time? i just completed my first arf and i plan on building more so invested $30 on great planes' cg machine. its pretty dead on as far as cg goes. it even has little rulers so all you do is set them to the planes specs, put the plane on the legs and there are little posts in front of the ruler that just touches the leading edge of the wing. plane dips forward- nose heavy, backwards- tail heavy. you can adjust your weight while your planes on the legs. just be careful and ALWAYS keep the plane within hands reach- if its bumped or if it dips, it may fall off. my 2 cents cory

I disagree.

If you're not laterally balanced, you're compensating with aileron input to create level flight and this creates unnecessary drag in level flight. A balanced plane is a happy plane. It's a good habit to get into.

This is what I did to add weight to a wing tip on my Sig Somethin' Extra. I covered my wings last after balancing.

somegeek

Balancing spanwise is worth your time. But don't balance just the wing alone. After all, either your muffler is off to one side, or the engine and muffler is, right. But don't knock yourself out trying to get the span balanced perfectly. But do check to see how badly it might be. The fore-aft CG is required to be close, however.

The two pencils balancer is a perfect example of "modeler in action." Excellent tool to make. And it costs you what?
But if you're a beginner, do some reading about fore-aft CG location. Don't expect your ARF mfg to suggest even a correct CG. There are lots of cases where the manual information is from another model, not there, or flat wrong. And most of them don't actually report how wide a range the CG can be in.

If you're a beginner, keep in mind that for most of our models that're 40size on up, the CG has a safe range that is quite a bit more than 5 or 10mm wide. Learn to use something like Geistware's CG locator application and teach yourself how this mysterious CG actually works. And don't get hung up busting your butt trying to get the CG to one spot. Learn to move the battery or equipment to get most of the job done, and expect to have to do it. But do find out what the fore-aft range is for each of your models. Take control. With understanding comes control. And it's actually pretty simple.

BTW, a 2x6 is quite a bit more stable than a 2x4 for a balancer.

And a bit of string is the cheapest and best.

Your fingers do a pretty good job of measuring the CG. Just measure back from the leading edge of the wing to the point where the plans say to.. usually over the spar, and then draw a straight line parallel to the leading edge close to the fuselage. Then put your fingers on the line and pick it up. Empty tank, of course, with battery, engine, RX, and servo's in place. If it tends to move toward the tail, then add some stick-on lead weights to the nose as far forward as you can. If it perfectly balances, add one small weight to the nose on each side to make it slightly nose heavy. If it is really nose heavy, then you will have to do something about that like move the battery pack back. If all else fails, then you will have to add some weight to the tail. This is unusual. It usually needs weight in the nose.

As far as lateral balance is concerned, well, some say yes some say no. It's totally up to you. You can check it by having someone help you. Use your finger and pick the plane up by having someone put his/her finger right on the prop nut and someone picking it up right below the rudder at the rear. Use your head. If it goes sligthly to one side or the other, forget it. It won't make a bit of difference until you are way beyond trainers. If it goes heavily to one side or the other, you will have to put some sort of weight on the light side until it gets close to balanced. The same stick on weights will work, but you have to make sure you put them on a solid part of the wing tip and not on a place where the covering is stretched over a rib or something.

I'm sure others will have something to say about this. This is just a guide. Just be sensible about all this. The main concern is CG. If it isn't right (tail heavy), you will not have much longevity with that plane. The lateral balance, on the other hand, is pretty much controllable by the aileron trim.

I also disagree with Bigdaddy. If lateral balance is out enough you can't do a simple manuever like a loop. The aircraft will want to roll out of the loop to the heavy wing.
I do believe in CG machines, a pencil is a very small area to put the weight of your aircraft on. Possible to send the pencils spearheading through the balsa sheeting.
Try not to add weight, instead move your battery and reciever around. if all else fails then add weight. I will cut open the monokote and use stick on weights then dab drops of epoxy to help hold the weights in place, if nose heavy. If tail heavy I'll put the weights around the fuel tank.
For lateral balance I cut the monokote open at the wingtip, and place a weight on the cg line on a rib or spar and secure with drops of epoxy.

I use the same CG technicque as "fellers" with no problems. He and I place "V" shaped add-on erasers which work well up to about 9 pound planes when balancing on balsa sheeting. I do recommend tapeing a small square of 1/16 ply at the CG area when balancing heavier models.

After many years of balancing in other ways I have used a cradle for the past couple of years. The string costs about 5 cents, all airplanes can be balanced in this manner, lateral balance can be checked at the same time, and the airplane does not fall. In addition it is easy to move servos and other parts on the airplane as a rough check during construction.

Bill

Read these:

http://www.rcuniverse.com/magazine/a...?article_id=84

http://www.rcuniverse.com/magazine/a...article_id=601

Here's my homemade CG machine, i have measuring cups over top of the dowels that way it spreads the wieght out a bit and doesn't put holes in my plane

thanx rock

I put a small drop of epoxy on the wing bottoms near the fuse at the recommended CG location, after finishing. I can feel these with my fingers so I am sure they are in the right place

so then what do you do with the bumps after you've balanced? scratchonly

You leave them there for checking again at a later date

I use a little trick ,MinnFlyer showed me. I use 2 pieces of stipping tape, you can feel them good with your fingers. Works so well , I use this on all my planes.

WoW! Guys thanks for the very useful information. I have learned much, much more than I expected.
Awesome site.

Like minn said leave them they are about the size of a pin head