I am just getting into larger scale airplanes and I have problems trying to balance them on my own. I hate to wait around for someone to help me, is there a CG device for giant scale or an easier way to do it. I also have a large biplane and would like something that would work with a monowing also. The old finger under the wing at the cg point with a 16lb and up plane is pretty hard. Thank's

Usually need two people to do this. Just raising by the wingtips. If you don't have an assistant, you would have to get a scale, pencil and paper, and a calculator and use this method:

https://www.flyinggiants.com/forums/...our-plane.html

Good luck

If it is supposed to balance on the tube, there us an easy way to do it. Slip the wings out just enough to get a piece of string around the wing tube. Tie a loop around the tube and slip the wings back on. Pick up on the string.

Go to the giant scale forum on RCU and do a search. There is a way to do it by weighing the wheels and some simple math. It's the same way full scale are balanced.

Vic beat me to it. We musta been typing at the same time.

What I do is run a string from the behind the prop to a hook in the cealing back down to the rudder. Now hang the plane so that its level. Drop a plum line from the hook to just above the plane. The plum line is showing you the cg. One man job.

I pick up the fuse by the wing tube without the wings on. If the nose comes down that is close enough to go fly it. 28- 40% planes can be safely flown with a very wide range of cg.

Some where in this forum is the formula for using scales to balance your plane. It works great.

I do what Rolling Thunder says for the initial flight. I then fine tune the balance until it flies like I want. I have no idea where any of my planes are balanced using measurements, i.e. x" from the LE, etc.

Ryan

I use the EZ BAlancer II and also the string method, I like the EZ Balancer because I can do it alone
http://www.ezbalancer.com/
But when I Have to move things at the field and want to see what changes in balance I make I run a line around my wing tube and lift it with a digital fishing scale, that way I can see if I got it too tail heavy and it gives me a good all up weight.

The EZ Balancer Lite says up to 14 pounds.
EZ balancer 2 says quarter scale and larger.

Has anyone used the larger version on 150cc aerobatic planes in the 40 pound range?

Happy Holidays!
Bob

Originally Posted by bob_nj

The EZ Balancer Lite says up to 14 pounds.
EZ balancer 2 says quarter scale and larger.

Has anyone used the larger version on 150cc aerobatic planes in the 40 pound range?

Happy Holidays!
Bob

At $230 , how many are being used?

I use a variation of the pencil paper trick that Vic3d referenced. The math is alot simpler if you use the main gear as your reference point.

Step1: weigh the airplane.
for big planes, put the scale under each wheel in turn and prop up the other wheels the height of your scale so the plane stays level. I use CD cases for this. Magazines work well too. Add together the weight measured under each wheel and you get the total weight of the plane.

Step2: Measure the distance between where the main gear touch the ground and where the and the tail wheel touches the ground.

Step3: The CG is located at the following distance aft of the main gear ground contact position:
CG position = (Weight of the tail X Distance between the mains and the tailwheel) / The total aircraft weight.


The beauty of this system is that you can reverse the equation in Step 3 like this:

Weight of the tail = (CG Position X Total Weight) / distance to the tail wheel.

Now, if you know where you want the CG to be, and you know the total weight, you can move things around inside the airplane until the scale under the tail reads the value you just calculated. Once it does, the CG is where you want it. I like doing this for figuring out the final position of batteries. If the scale under the tailwheel reads too low, I move things in the fuse aft. If the scale on the tail reads too high, I move things forward. It makes it really quick to do find adjustments.

Hope this helps,
Tom

I just made my own balancer with scrap wood and a couple dollars worth of hardware.

I agree with Tony and Ryan. If i check them at all, I pick them up by the tube with the wings off. If the nose drops slightly, or stays level, we are good to go. I will then fly it and adjust it to how I want it to fly rather than worrying about measurements. My last 2 40% arfs, I didnt even check the CG before the maiden, as I built them using common equipment, put in the factory positions or more forward than factory, and to be honest, I have flown some severely tail heavy airplanes and they were never squirrley in the air, landings were just a little different.

I like all of the answers I am getting. Atleast now I have advise that I can take to our club and help others out. I especially liked the homemade balancer by Aerobat. I will try all of them and see which helps the most. Appreciate the quickk response. I fly a QQYak that is slightly tail heavy and it flies perfect. Thank's again.

Originally Posted by bob_nj

The EZ Balancer Lite says up to 14 pounds.
EZ balancer 2 says quarter scale and larger.

Has anyone used the larger version on 150cc aerobatic planes in the 40 pound range?

Happy Holidays!
Bob

Yeah I use the balancer 2 on my 40s and bigger.

Originally Posted by TheTank

I agree with Tony and Ryan. If i check them at all, I pick them up by the tube with the wings off. If the nose drops slightly, or stays level, we are good to go. I will then fly it and adjust it to how I want it to fly rather than worrying about measurements. My last 2 40% arfs, I didnt even check the CG before the maiden, as I built them using common equipment, put in the factory positions or more forward than factory, and to be honest, I have flown some severely tail heavy airplanes and they were never squirrley in the air, landings were just a little different.

Tank, you can slide the wings on and pit about 4 threads on the wing bolts where you have just enough room where the string will slip, this gives a better idea of where you are, and you can still do the digital fishing scale to see how heavy it is.