I'm balancing a 4*60 with a osfx61 engine turning a 13x6 wooden prop I have to ad 9 oz. of weight to the nose the question is , Is this to much weight? my cg is 3 3/4 inches from leading edge of the wing. here is a pic of the plane[img][/img][img][/img]

You have to add what it takes I would try a heavy hub to get it as far forward as possible and move the radio as far forward as possible. Should ballance on the spar just about. Ballance it upside down so the wing is on top to give you the most reliable reading.

Do you have your battery under the fuel tank all the way up against the fire wall?

Randy

I think the 4*60 just builds tail-heavy to begin with. I am just completing mine, and with everything as far foward as possible, including the engine, battery, and servos, it will still need quite a bit of lead. I am also using a relatively heavy aluminun spinner nut.

Mine had 4 oz of lead in the nose with the battery under the fuel tank against the fire wall. It did not seem to affect the flying qualities. It has such light wing loading that I wouldn't worry about it!
John

I wouldn't worry about 9 oz. but I do question all these results. I fly my 4*60 originally with a YS91AC 4 stroke and now a TT .61 2 stroke and added no weight to the nose. It balanced perfectly with the battery under the tank.
Or are we talking the ARF??

I have both the ARF and the kit version and I had to add no weight to either one to get them to balance. The ARF has a GMS 76 engine on it and the battery is under the fuel tank up aginst the fire wall. The kit built plane has a Magnun 91 4 stroke on it and the battery is back aginst the rear wing mount bulkhead. Both planes fly great and I love flying them. The GMS engine is the best running 2 stroke engine that I have ever had. It ran perfect right out of the box and only needed minor tuning. It gives the 4* unlimited vertical performance. The magnum also flies the 4* really good and it sounds so sweet. The vertical performance is not as good as the GMS but it still hauls the plane vertical pretty good. It will not hurt to have to add a little weight it will still fly great.

Rick

My battery was a 600 mAh with an O.S. 61 FX. Maybe that had something to do with the differences?

Thanks everyone , The plane was a kit built type, and the battery is located in the servo bay area up against the 2nd former . I will move it farther forward up to the firewall and check the balance again. Also I'm balancing with the plane upside down. I'll let you all know how it balanced tonight sometime. Thanks again

It looks like you have made your decision, but just wanted to add that I had to add weight forward as well. The battery is under the tank, I have a weighted prop nut, and have added lead in the engine well. I have a OS91 surpass, and even the extra weight of it still did not help that much. BTW: Mine flies great, it is one of my favorites to fly. One thing it did though, I replaced the inner ny-rod with a steel one. I found that temp changes did affect my trim on both the rudder and elevator.

Sometimes you can mount the engine a little farther forward in the engine mounts to help with the CG. Also, when building a plane, it's a good idea to check CG before covering it. At that point it's easier to make changes.

Also, wooden props are lighter than the nylon ones. That's an ounce or two there.

Hi again, Just wanted to let everyone know that I've moved the battery up against the firewall below the fuel tank,and again checked the balance of the plane, by doing this it reduced the nose weight from 9 oz down to about 4 oz of weight I will have to add.I feel this is a safe amount I will have to add. I could move the engine farther forward on the motor mount, but feel this is not necessary for only 4 oz of weight difference. I will put on a alum. nose cone instead of a alum. nut, and I could add 2oz prop weight, to the engine. Thank you All for the advice, it made a difference, This is what makes R/C universe what it is with so many nice people like yourselfs helping other people. Thanks again

I think someone beefed up his 4*60's tail end...

Mine balanced correctly with a O.S. .91 FS (weighs less with muffler than my K&B .61 with its muffler) and the battery was over the TE of the wing. No lead anywhere...

The 4*60 can handle having some added weight. I added retracts to mine just to add weight to it. (Well... I wanted to "play with" retracts too...) And it was still a floater.

BTW.. with the retracts pulled, and the stock landing gear installed... the battery had to be move back 5 more inches.