I balanced a Goldberg Eagle 2 as per the directions, 4 inches behind the leading edge. I have a Hanger 9 alpha that was balanced at 3. I understand that different aircraft have different characteristics, but the flight characteristics of the Eagle were a bit troubling on maiden. I took off three times and each flight I noticed that as soon as I tried to turn the nose went up, the tail dropped, and the plane stalled. It held level on approach, but seemed to be a bit tail heavy upon touchdown, as it would bounce from tail no matter how mellow of an approach. The turns could be completed with a little work, but it seems to me that the tail is a bit heavy. Any balancing tips, and explanation of what happens with a tail heavy vs nose heavy aircraft would be appreciated.

IMHO. If the tail drops bad in a turn that is too tail heavy and 4" sounds too far back. I have not had this model just speaking in general. I have a World Models Trainer and I like it. I had a 4*60 and it flew better than my trainer. Maybe cause it was bigger..

ANYWAYS>. The trainer I had was 3" back. I had it just a bit tail heavy like 3.25 but that made it fly better after I done that..

I would check it again and move it forward a bit. Jsut a little at a time. .25 max each time.. That is how I do it. With a trainer it seems the large wing would be forgiving in this area but I guess it is just as important as any other model..


LATER

Were the instructions written using a 4 stroke? If you move the Cg up (toward the nose) you're going to make it more tail heavy. If you're at 4 inches and the tail is still heavy, you might have to add weight or put your radio and battery in front of the cg. my Ultra Sport and Ultra Bipe were the same way They call for a .40 - .60 2 stroke or .70 4 stroke. The .70 4 stroke is about the same weight as a .60 2 stroke.

The motor makes no difference as far as where the CG should be. I don't think you fully understand what CG means. CG (center of gravity) is not some imaginary line on the wing of an aircraft. The CG of an aircraft is where it balances on the chord of the wing. To move the CG Fore ("up"), you add weight to the nose. To move the CG aft ("back"), you add weight to the rear of the aircraft. The instructions are written with a range within which the plane will fly like it is supposed to, as long as the plane balances within that range. So, in other words, if the instructions say that the CG should be set at 3 1/2 to 4 inches back on the wing at the fuse, that means your plane should balance somewhere within that range. If you plane balances at 3 1/2 inches, then that is the CG of your plane. If it balances at 4 inches, then that is the CG of your plane. If your plane balances at 5 inches, then that is the CG of your plane, and you should move the CG forward to within the acceptable range by adding weight to the nose of the plane.
The best way to move the CG fore or aft is to move the weight that you already have around--i.e. the battery, receiver, and servos (if possible). Also, adding a larger, heavier engine is acceptable if the plane is too tail heavy. However, the CG range recommended within the instructions has nothing to do with what engine you are going to put on it.

MAN ARE YOU SELLING AIRPLANES TO BEGINNERS?

BEGINNERS LISTEN UP: If your airplane has a straight rectangle wing, then simply measure the chord, Leading edge to trailing edge, including ailerons, and use 25 to 30% of that distance as the balance point along the lateral axis - the axis parallel to the wingspan -- located at about 25% of the mean aerodynamic chord (MAC) measured back from LE. On any subsonic airfoil the center-of-pressure will be at 25% MAC which is an ideal stable Center of Gravity (CG). Your model will become more unstable as you exceed 30% of MAC aft from LE, and probably a bear at 35%. If the chord is 12" then the 25% point is 3". More than 3.6" (30%) and you're flirting with dangerous instability.

OTOH due to the design parameters some Pattern models can tolerate 40% aft CG, however those pilots are expert pilots using the very minimum control throws. When you get there you will not need this conversation.
Most kits are in the ball park however I have found several that promote a CG too far aft. Maybe something gets lost in the translations.

For straight taper wings, the MAC will be just outside the AVERAGE chord of the wing panel, however the use of the average chord will provide an excellent place to start for a good flying model. There are several places to find the computations for finding the exact aerodynamic chord.

Last year I assembled a Hobbico trainer for my grandson, and both the GP Lil Toni and the Shoestring. Using the graphic methods to find the MAC, and computing my own CG, I found GP's marks to also be at 25% MAC. They did good!! Both models flew/fly excellently. On the trainer I added a couple ounces up front to make it a tad more nose-heavy and make him work a bit harder to learn to make a good round-out for landing. He did.

Way TMI,,,,
If the plane is tailheavy, move the battery back more forward until it balances. On a Trainer like yours its going to balance on the wingspar.
1. Get someone to help you and find the wingspar, with the fuel tank empty each of you get on a wingtip and put your finger under the wingspar out towards the tip. Lift the airplane with you fingertip under the spar.
2. If the tail drops a little its tail heavy, if the nose drops its noseheavy.
3. Move the battery pack forward or back until the plane balances.
4. Thats it!

There are lots of possibilites that can cause your problems. CG and being out of trim are the two most likely. Theres a real good chance that you just need to add some down trim in the elevator.

Turn on the radio and reciever in the plane and look at the elevator from the end. The elevator and the horizontal stab should be in line with one another. If the elevator is deflected slightly upwards then either mechanically adjust it by shortening the pushrod till its straight, or if its just a little bit. GO ahead and add some downtrim to make it line up with the stab.

If you have a larger engine that recommended in your plane and you assembled it otherwise according to the instructions it is very unlikely, almost impossible that you are tailheavy.