funnotcrazy

Have built a number of planes and usually mark the CG area with some trim tape, then hold my fingers under the wing near the fuse. These were smaller planes up to 60". How do I balance one with a 89" span that is so much larger?

sensei

There are many gimmicks out there to do this but I always mark my C/G range on the wing tips, get a flying buddy and pick them up by the wing tips, even my 55% airplanes with 164" spans.

Bob

flying co

built a stand to assemble the winges out of 1'' pvc have round caps on front end have a small 1/4'' piece of velro on center of cg set the cg point on the round caps if the balance is tail heavy the stand keeps the tal from dropping to far. can use at home for building and at field after attaching wings

foodstick

Sometimes I have drilled small holes on both sides of the fuse right on the CG, when I build it I reinforce that area inside the fuselage so I can put two wires bent like an allen wrench in the holes and lift by those points. you could also have the wires tied to a cross beam above when doing this. Its a good idea for warbirds and certain types of planes, but obviously is not gonna look good on a shiny show plane..Its just another route to go.

STUKA BARRY

I use my fingertips on the CG for my 1/3 scale 32lbs. Fokker D-VIII, 1/3 scale J-3 Super Cub, invert my 28lbs. Stuka and use fingertips, my 40lbs. P-40, etc. I think I'm going to have alittle trouble with my 120" w/s Fork Tailed Devil, but all other are no problem.

Gtarling

Vanessa CG rig - simples! http://www.youtube.com/watch?v=h57T8OXH4qk

flycatch

My Feedback: (26)

Purchase a commercial grade balance stand.

earlwb

Well up to a size maximum that depends on your strength and thiumbs, I just use my thumbs under the wing. But when they get larger than a 50cc plane it is a problem though. I haven't built one that is that big yet. But I would expect to need a CG balancing stand of some sort. But at those sizes you start to need more than one person to help out too. I have thought about using a couple of saw horses with a couple of dowels with semi rounded ends like on a broomstick handle for example. Then see how the plane balances on them. But I haven't gotten that big with the planes yet. So I haven't had to contront the issue.

grosbeak

When I went to 50cc I started using scales to balance the plane - check out this article

raptureboy

Vanessa rig http://www.rcuniverse.com/forum/tips...g-rig-how.html once I tried this I would never go back to balancing on some teter totter device even if you gave it to me. Stores in a drawer and I can hoist up any size plane with ease and not have to worry about it falling off. Your opinion may vary.

Giant_Scale_Gasser

My Feedback: (84)

I used 1" PVC and made my own balance stand. I used a 1 1/2" Tees at the top for the pivot. That is a 104" Span Godfrey Extra 330L on it and it works perfectly.

B Shipp

My Feedback: (13)

Agree with using scales. There are plenty of spreadsheets available to plug your numbers into to determine your CG. You will also get the added bonus of knowing what your aircraft weighs.

retransit

My Feedback: (18)

After purchasing a Great Planes balancer and using it for a few years, it was not up to the job on bigger aircraft. I now use a piece of cord looped around the nose and tail and supported on a substantial hook. A plumb bob is dropped from the apex of the cord at the hook. A small bubble level is placed on the horizontal stab. When the stab is level, the plumb bob will point to the CG. After that, all you do is move your weight or components to get the CG within limits with the bubble level on the stab. The last plane I used it on was a 24lb. Fleet bipe.

gesmale

My Feedback: (40)

I believe in the KISS principle. I have watched Sensei build and fly for the better part of 20 years and he has never had a CG or balance issue. The fingers at the wing tips will always work. All the rest is academic.

SkidMan

My Feedback: (17)

I made a quick Vanessa rig and love it. You can see the C.G. right from the pendulum.

I'm sure that I'll do the scale thing sometime soon. The problem with the procedure that Grosbeak links to is that measuring the weight of the three wheels, with the wheels all level with each other, will result in a C.G. that is aft of the actual C.G. which is measured with the longitudinal axis of the airplane level. The C.G. of full size planes is measured with the lateral axis of the aircraft horizontal, not in a landing attitude (all three wheels level on the ground). Simply stated - the airplane needs to be level (as in flight), not resting on a flat surface.

http://avstop.com/ac/weightbalance/ch3.html
http://members.eaa.org/home/homebuil...%20Safety.html


Paul

Doomking

My Feedback: (38)

Vanessa all the way.......

2walla

My Feedback: (10)

I tape a couple of dowels to the wing along the cg alignment then place it on a couple of sawhorses.

sensei

Now when I balanced the Staudacher @ a hefty 425 lbs. I used a spread sheet and did the math. I will also agree that everyone should know what their airplanes weigh but most I have found do not.

Bob

2walla

My Feedback: (10)

Ignorance is bliss....

retransit

My Feedback: (18)

I use fingers at the wingtips when I want to quickly verify the CG. The initial CG'ing takes something a bit more sophisticated. That is why I use the cord and plumb bob.

GPutt33

My Feedback: (2)

After getting into the 120 size planes and then the gassers, I wanted something larger to help balance while still working in the shop so I built this. Pretty simple and easy to make with a drill press and hand tools. It's HD, does not mar any wings and is user friendly After you get it completely built and want to check things quickly, like the guys said, using a buddy to help at the wingtips works great as well.

sensei

How you doing my old buddy? Hope all is well...

Bob

saintcreed

My Feedback: (205)

like grosbeak, the way to do it alone, scales is the easy accurate way. with very little chance of something breaking, tipping or what ever and damaging the plane..all one needs is a simple digital scale (10 pound postal works fine),tape measure, calculator, pad of paper, 7 pen or pencil. two wooden pads built the same heigth as the top of the scales...

gpoore

My Feedback: (45)

Brilliant! great idea

2walla

My Feedback: (10)

Hey Bob. Been doing ok. Took a promotion and now have 20 or so people to ride herd on. So much for cutting out the stress. Trying to get some time to get my shop in order for winter before the snow flies.
Mike