Hello. Just finished the construction and covering of the SIG Kadet LT-40 and I need help to get it properly balanced. The instruction manual set a balancing point for beginners of 3 1/2 inches from the leading edge. There is no way I can get it balanced there. I moved the battery pack and the receiver all the way up front to no avail: still too tail heavy. (the balance I got was one inch to the rear of the balancing point). Adding weights to the front was my next step, however after adding about 8 oz the balance was still way back. Now I am perplexed since I followed exactly the plans and instructions and I can't get it right. The engine is an OS LA 40. Is it the culprit because maybe the plane was designed for a heavier engine? Any ideas on how to correct this? Thanks!

The CG is between 3 1/2 to 4 1/4 behind the leading edge of the wing. You might want to move the engine forward some if you have the room. I have a OS .46 FX in mine and have no weights added for balance. I have a metal spinner which adds weight to the front of it. Instead of one of the plastic ones.

I have the Kadet LT-40 also with a OS 40 FP engine on it. My plane is balanced about 1/4 inch aft of the main spar. I also have a heavey hub prop nut on it as well. Put your C.G. to the aft limit or you will need alot of lead in the nose and when t comes time to land the airplane just keeps flying by with the fwd C.G. Even with the C.G at the aft limit the airplane has a gentle stall and flys much better and slower landings.

Wow! That sounds like a lot for a trainer to be out of balance, especially one made by Sig. Of course it's difficult to say why without actually seeing it. You can do as the other contributors mentioned, you can also add a Higley Ultra Heavy Hub. That adds 4oz. of weight out where it will be the most effective. Basic rule of thumb for balancing, fore/aft is 3 to 1. Meaning, for every 1 unit of measure added to the tail you must add 3 to the nose to balance it. I would go back over the plans and compare it to the aircraft very closely to see if you can locate the problem. Are you certain the main gear are in the proper place? It's not difficult to make some sort of mistake like that. Don't ask me how I know that either.

I built the LT-40 kit and put an OS 40LA in it. I had to add 5.5 oz of lead to get the balance in the center of the main spar. Where did you put the weights? I put them inside the cowl cheeks. It helps to get them as far out front as possible. Andy

My LT-40 balanced well with a ThunderTiger Pro 46 in it. The positioning of the engine is critical and the best way to balance the bird. Move the engine around until you get the best balance. As suggested, prop nuts and weights can do wonders but I would take a good look at the receiver battery. Mine is positioned under the fuel tank.

Hud

I built the Kadet last year and had the exact same problem. Very tail heavy aircraft. I have put an OS .46 fx in it now but didn't help much. I am going to move it way out forward and remove the weights I put in the tank area. Fly's ok. At least when the servo arm screws are in place[sm=crying.gif]

Thanks for all the sugs. I had to put about 9 oz of weight on the front to get it balanced. I read that this kit was designed for a heavier engine (Magnum?) that weights almost double than the OS 40 LA. No way I could move the engine forward, so I decided to add weight although I dislike a bit this solution.

I had to add 9 oz. to mine and asked the same question. It flew great right up to its expiration date.
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