Plane is very tail heavy. Plans show cg at center spar. Is this too far forward? I have a saito 82 4-strok mounted.

What are the symptoms? If it is unstable in pitch then it is tail heavy. If it just needs down trim, give it some down trim. Also check your ailerons to make sure they are not a little bit down and functioning as flaps. That could cause a need for down trim.

I balanced mine at the rear of the suggested range and like it that way.

Jim

Edit: Re-reading it sounds like you haven't flown it yet and are just trying to get it to the specified CG. I balanced mine with an OS 70 FS, but I had lightened the tail some, and also got the battery well forward, under the tank, I think. I also used an aluminum spinner, which helped.

Don't fly it tail heavy. Use a heavy hub if you need to. Then you can carefully try moving the CG back, a little at a time, depending on how it flies.

They come out tail heavy. One I built used the Saito 100 and took a lot of work to get the CG set as shown. I don't recall but I think I had to add lead. Last one I built had a .75 two stroke and needed lead in the nose. I try to never add weight to any of my builds but sometimes it is required even with all the gear placed forward of the CG. Fantastic plane even with the added weight though.

Yeah, the thing about the 4-stars is that they're floaters, so you don't have to worry about the added weight. My Venture 60 (similar to the 4-star and designed by the same person) came out two pounds heavy and is still a floater. Midstar-40 with clipped wings, lead in the nose, and a .35 for power, still a floater. 4-star 40 with lead up front, floater. There's a pattern here.

Mine has a butt load of weight in the nose, balanced where it shows on the plans. You can't miss as they all fly like they are on rails. Mine has a Saito 80 on it. Good Luck, Dave

I have exact same plane and motor with the same problem.took 10 oz. hanging off prop shaft to get cg in range. I figure I will need 12 under motor.very unhappy about that.i read they come out tail heavy and was careful while building tail.looking four a 90 2-stroke now.power is better than lead.

Maybe a DLE 20 would help to balance?I think that would be a good combo.

I think a dle 20 would be great also and would solve balance problems .i have considered the engine but I have never run a gasser.the worries I have are prop clearance ,learning curve,and if air frame would hold up to that much power.i am sure all these problems could be overcome.thanks for the suggestion .

Mine balanced perfectly with no extra weight. I tapered all control surfaces with a razor plane, made a balsa cowl at the front, OS 70 FS, covered with silk and dope. Jim

Mine was/is good with a Thunder Tiger .91 fs up front. I did add leading edge sheeting.