castaway_bill

I recently acquired a "Little toot" biplane. Its 57" span which I believe makes it 1/4 scale.

Naturally I'm keen to get it in the air, but I need to know the centre of gravity location, and also recommended control throws would be nice. If anyone knows this info, or could read it off a plan, I'd be most grateful for their assistance

Regards

Rob

BobH

My Feedback: (2)

Try this link. 22-25% of the MAC (mean airfoil cord) should be a good place to start.

http://www.modelaircraft.org/newsletters/0903_15.asp

castaway_bill

Thanks for that.

I know that for a single wing, the C of G is somewhere like 25% to 30% of the MAC. So your figure of 22-25% would suggest that for the biplane the C of G is generally set a bit further forward?

Also I found this http://users.adelphia.net/~pjburke1011/cg.htm , which has a link to a MAC calculation program.

Regards

Rob

BobH

My Feedback: (2)

Rob there is also the amount of stagger of the wings needs to be considered. Some place I have a good explaination of determining how to figure that out and then where to place the CG. If I can find it I'll post it.

castaway_bill

Thanks Bob, I'd really appreciate that

regards

Rob

EF

Rob

I have the plan for the same size Little Toot (from RC Model World).
The CG range is shown at 120-130 mm measured back from the L.E. of the top wing at it's centre.
The control throws are shown to be:
Rudder 1.25" each way
Elevator 1.75" up and down
Ailerons 1.25" up, 0.75" down.

Good luck!

castaway_bill

Hi

Thats just the information I needed - many many thanks!

Regards

Rob

castaway_bill

I fitted a saito 125 4 stroke, and set the C of G to about 125mm, as discussed above. Flew the model over the weekend, and the results were great - it looked and sounded pretty damn good, if I do say it myself!

If anything is still feels a little nose heavy, also the wooden pushrod for the elevator is less than precise, I'll maybe convert to closed loop or more likely fit a couple of direct acting servos at the rear. I might need to move the battery forward a little to compensate for the latter.

So I just wanted to say thanks to both of you for being so helpful.

Regards

Rob

BobH

My Feedback: (2)

Rob glad everything worked out for you..