Adjusting CG
 

I've just finished putting together a Hanger 9 Alpha 60 trainer, and the CG is off by about .75 inches (nose heavy).

Using coins on the tail I can easily move the CG to the proper spot, but it's taking a bit over 4 oz. to do so and have the plane perfectly level. Since it's such a simple aircraft the only internal option I have is to shift the battery towards the tail, but without cutting the covering I'm not going to be able to move it very far, and it's fairly light anyway.

Is this an excessive amount of weight to bring it into balance?

The engine location is spot on with respect to the firewall and thrust washer, and in any event there is virtually no room to move it back slightly anyway. With a simple aircraft like this I figured that the CG would be almost correct right out of the box, so I'm a bit surprised. This is my first plane, though, so I don't really know if this is typical or not.

Thanks,
Bob

RE: Adjusting CG
 

It's not uncommon to have a wooden airplane need some balancing, especially ARF's. When we build a kit, we can select the wood we want based on it's weight to help our balance come out right, but the ARF makers can't afford to do that at a price we're all willing to pay.

It's pretty simple to cut a small hatch in the underside of the tail to relocate your battery, some here have good photos of how to do that. It can be quite seamless and clean!

If you don't want to cut covering, you've still got a few options. You can try to remove weight from the front (lighter front tire, wooden instead of plastic prop, lighter spinner, etc.). Once you've exhausted all those options, add weight. For the record, 4oz on an Alpha 60 won't be noticed. Huge wing area, lots of power. Don't sweat it if you must use weight.

My first trainer is a kit bashed S-ray 25 size 3 channel job. Built and bashed by a friend. It's nose moment is so short it took almost 1/2 pound of lead to balance. This is a .25 size plane! Flies great, slow, fast, good climb out, fine handling. It is far more important that the CG be correct than that the plane be lighter than light. Make what efforts you can to keep the weight down, and then do what you must to correct the CG.

J

RE: Adjusting CG
 

Adding four oz. of weight to the back will work fine if that is all you can do to get it to balance.

RE: Adjusting CG
 

Nah, that's fairly common to have to adjust the CG. Did you try to move the battery further back in the servo compartment? That may do it for you.

CGr.

RE: Adjusting CG
 

As others have stated. Four ounces isn't a lot of weight. I put a 7oz camera on my 63" 40 sized trainer. It made no difference (to me) in how the plane flew. The weight might make a difference on a 3D plane in pulling vertical or not, but a trainer..... no sweat.

That being said, I'd rather find that four ounces by moving stuff around. If not, I wouldn't worry about it.

Plastic spinners are lighter (and cheaper) than aluminum ones.
Sometimes, depending on the location of the servo, the throttle servo can be changed to a micro and save a timy bit. That's only really worthwhile if you have one laying around.
Sometimes you can glue/velcro the battery inside the tail by using a dowel to stick it down there. Mine is located about 6" behind the wing just for that purpose.
Lighter nose wheel
I'm sure there's more tricks.

RE: Adjusting CG
 

I usually balance trainers with the nose a little heavy. 2 to 3 degrees down angle on the fuse. That way when you run out of fuel, it is easier to dead stick in. When I train, dead sticks are not uncommon from using all of fuel flying. As already stated, 4 oz in a 60 trainer won't be noticed.

RE: Adjusting CG
 

I agree i put a 7oz camera on a GWS slow stick and i think it flew better, and it's just a light stick and foam trainer.