Balance weight.

[David Barker 2]

I have got ARF SIG 4 Star 64, my first low wing plane. The engine sizes they quote to use is glow power 4-stroke .60-.90 or 2 stroke .60-.75. I have a spare 4 stroke .60 to fit. This has been assembled as per instructions Battery fitted right up front under fuel tank. Starting point for c of g is 3.5 inches from leading edge. Engine weighs 450grams. Now find I have to fit 12ozs of weight up front, which seems to be a lot to get the c of g correct. The standard servos in fuselage are as near to c of g as you can get. Do I go ahead with ballast weight, of would it be easier to get a bigger engine and put less ballast in. Thanks Dave.

[Alan Pennington]

Hello David,

I look at this way, you could put a bigger engine in to increase the weight on the front to get the cg right. But that could mean going out and buying another engine, or adding 12ozs. Me I would see how it fly's with 12ozs up front first.

[Denis Watkins]

As Alan says Dave, try it

But double check the C of G with the Sig Inverted

A bigger motor is only a few oz heavier anyhow

So try it, but don't add 12 oz to the cowl, it would break the cowl on heavy landing

Get the weight taught against timber

[Peter Miller]

I am extremely surprised that a Sig model needs so much ballast. Sig are normally excellent models.

Mind you I am going by the kits but I did review their big ARTF Rascal many years ago and that was excellent ans needed no ballast

[Jon H]

As you are at the bottom end of the engine range a bigger lump is an option here, but it wont give you 12oz thats for sure.

It has to be said that i have never been that worried about adding lead for balance. If i have done all i can to minimise the dead weight then thats all i can do and as it must balance to fly i fit it and forget it.

[cymaz]

A 91 four stroke will be in the region of 650g. Useful and usable weight up front. That's about 7 oz extra.

Is the quoted CG correct..?

Edited By cymaz on 02/03/2017 19:31:06

Edited By cymaz on 02/03/2017 19:32:07