I purchased a Goldberg Ultimate that was already built. It was an excellent job. I checked the CG and thought it was on the manufacturers recommended location. But I am not liking the way this plane flies. It has only been up maybe 4 times. I have two major problems. It seems it needs way more elevator throw than what is recommended. Unfortunitely CG ongives out degree throw which I don't have, but I tried 3/4" as recommended by some one. Not near enough. I now have 1 and 1/8" of throw and this is just barely enough to retain elevator response when landing. The other problem is that this plane needs full forward stick to retain level flight when inverted so it looks like the CG is way to far forward. The engine is a 1.08 OS. Any comments/suggestions. thanks.

Get a piece of cardboard. Line up a protractor on one edge and mark the degree of deflection that is needed. Lop the angle off and now you have a template to accurately measure the deflection on your stab.

I've had a couple of CG Ultimates w/120s and I absolutely loved them. We used to quickly check the cg with the wings off by lifting the plane by the horizontal part of the cabane with one finger about 1/2" back from the front.

This is a great flying plane when set up right. Check your incidences and engine thrust too. This is where an incidence meter is worth its weight in gold.

You will probably need more throw for take off and landings than their reccomended flying throws. And you will definately need more for 3D

The reccomended flying throw is actually porbably more than you need if you are wanting to fly a smooth pattern with it. They tell you that throw so you can be flying full speed pull full up elevator and not snap your plane into the ground. Smaller planes like these will tend to snap with too much speed and too much throw(thats what rates / conditions are for). Hope this helps.

The plans [original old kit] shows the CG to be 1 to 2 inches in front of the rear cabane . You may want to go back father , but this should be a good starting place .
Hope this helps
Maj. Crash

I fly in a dirt runway, in low throws it take a full charge to break ground, lows are about 60 % of high rate!;
I now use high throws only on elevator, however first 4-5 flight didnīt.
I fly with a OS 91 FX & 15X6 zinger-pro wood prop. so is not that fast and no snaping trends happens at full up!
I went to maximun rudder and ailerons are as recommended.
It is a hair nose heavy but it īs o.k.for my flying skills level
this ultimate is my favor plane so far.-

I have checked the CG very carefully and determined that the CG was at the forward edge of the range (1&7/8) with an oz of weight in the tail. The plane flew real tail heavy. I have had to raise the tail weight to 3.25oz to get the CG back to the rear of the CG range (2&7/8). Will not be able to flight test until this weekend.

I am going to try the elevator at 1&1/8 (HR) and this CG to see how it goes.

I am kind of thinking this plane was sold because the owner just never took the time to adjust this CG problem.

Moving the CG back is the right way to go. BUT it's not a great idea do jump all the way back in one move. I would go back perhaps 1/2 or 3/4 the distance. Test fly it and then go back more if needed. If you know it takes 3+oz to get the CG to where you are now you could test fly by adding only 2oz at first and then if needed tape another oz at the air field and fly again. See if that is the right place.

The Ultimate is such a short fuse that once you go back too far by just a little, its too late.

If its nose heavy it will land hot, if its tail heavy you don't need to worry at all about landing, quick thumbs may save it, but not worth the risk.

tonyc

Tonyc. Actually you are correct. Since posting my last I had backed off an oz in the tail until I could fly here at that intermediate change. I had remembered that I had crashed a Majestic because I had moved the CG just 10mm to far back difference between a great flyer and a wreck. I'm hoping to fly her after work today if the winds go away for the first time in a couple of weeks.

I have an ultimate i built a while ago...I had a supretigre 91 on it and now im adding a servo for the wing and sheeting the elevators. I think i will try two servos for the elevator halves. Does anyone have suggestions or comments? I only have a Saito 1.80 4 stroke left to put on it. Is it going to rip it apart? Its lighter than the 1.20