C of G

[Tom McDade]

I have just put my ready to fly kit together but have read that I need to balance to plane. I am wondering if I should leave the factory setting as they are (The tail is low) are all plane different and should I try and fly the plane first?

[Myron Beaumont]

Tom
The C.G is THE most important factor in any design.You mention factory setting.If you have to ,it is imperrative that the nose is slightly down (gliding angle )when you balance it .statically.Add weight if necessary but Never Never fly it nose light (unless you are into fly by wire or 3-D .) Just my opinion but I think I'm right !

[Mike Rolls]

Myron may think he is right - I know he is!!

Mike

[Tom McDade]

Thanks guys.
Am I right in saying then that if I balance my plane on my fingers 1/3 toward the tail from the leading edge then the plane should be slightly nose down. Are there different points of balance on different planes or is this a general rule.
Regards
Tom

[Kelly]

Hi Tom
If you have built from a kit the instructions should stipulate the correct C.G for your aeroplane.
Regards
Kelvin

[Tom McDade]

The intructions are of the upmost quality and cover every aspect of initial set up of the aircraft.
"Electrosise the battery firstly before you to fly the plane"????
But I supose whoever wrote that speaks better english than I can speak Chinese...
Regards
Tom

[Mike Rolls]

Tom
There is no general position for the CG - it depends upon the layout of the wing (tapered, not tapered, swept back, swept forward, etc.) the size of the tailplane in relation to the wing and the distance between wing and tail (momnet arm.
Assuming that there is nothing helpful in the instructions you have trhee alternatives:
1. Return the kit whence you bought it as unfit for purpose
2. Guess - possibly wrongly with disastrous consequences
3. Use if the accepted formulae for determing where the CG should be.
If you prefer option 3 let me know your E-mail address and I can send you an Excel spreadsheet whihch can work it all out for you - all you need is a ruler and to input the numbers
HTH
MIke

[Bob Howard]

One point to mention - if the model has an IC engine, check the CG with the fuel tank empty.

The model will then be slightly nose heavy with a full tank of fuel - that is much safer than having a model which is tail heavy when the engine stops because the tank is empty.

You could try moving the receiver battery to a more forward location (under the fuel tank is favourite), otherwise fix weights to the nose area - the further forward the better.

If your model is electric, check the CG with the flight battery in place. If you fit larger or smaller batteries, recheck the CG.

Models which are a little nose heavy are a bit sluggish, but safe to fly. Tail-heavy models are unstable to the point where they can be totally unflyable.

[Tom McDade]

Hi Mike
I think I have it now. I did the 3rd from leading edge test and hand launched her with no power. She glid(?) nice and straight nose down. I then powered her up and she flew great. I could still do with looking at that spreadsheet though.
[email protected]
Many Thanx
Tom

[Chris Hornby]

You can edit the cg in flight sims. It is a good way to find out the way it affects the airframe without doing any damage. I use FSone which is a bit clunky because you have to come out of the sim every time you want to make a change. It would be nice if you could move it around while actually flying the plane.

[Mike Rolls]

Tom
I'll post it as soon as I sign off here - I'll entitle it CG calculator so that you know what it is.
Mike

[Tom McDade]

Thanx Mike
I have recieved it but not used it yet. I'll let you know as soon as I do.
Thanx again.