sclitheroe

Hi all,

I'm building up my first kit, a 6' wingspan DeHavilland Otter from Unionville hobbies, and it's going pretty good. I was wondering what size tank you'd recommend for installation in a model with a 6 foot wingspan, 8 pounds all up weight I believe, according to the box, being powered by an OS FS-56 four stroke. I have enough room for a 14 ounce tank, but that's probably overkill, right? The Otter is a STOL bush plane, for what it's worth, not a high performance model at all, and I plan on flying it in a scale manner, no stunts.

Thanks,
Scott

oldvet70

My Feedback: (10)

I'd go ahead and put the 14oz tank in. Unless you see some type of finished weight problem, or a CG problem, more fuel is not a problem. As you say this is not a high performance aircraft so the extra fuel should not be a problem to haul. It should give you nice long flight times with fuel to spare.

carlbecker

My Feedback: (3)

The other side of the coin is carry enough fuel for the flight time wanted plus some extra. Don't carry fuel you are not going to use. I like 10-15 flight times, the lighter the better. With a 56 engine 10 ounces should give long flight times.

tstotts

Hey guys these planes have been tested under flight conditions by the manufacturer to give the right performance under various concitions conditions. Fuel weighs and effects the cg so if the plane is properly balanced the plane starts its flight a little nose heavy and if flown to nearly empty it loses nose weight and lands easiest when the tank is empty. Also different engines produce different pressure to the tank. The size of the tank effects the usable pressure. If you want the plane to fly the way it is meant to fly you might want to stick to the plans. Just my 2 cents for what its worth. happy flying..

Charlie P.

Eight pounds of model seems like a lot to expect from a .56 4-stroke. Personally, I'd go with a 10 oz tank.

C.G. Balance is done tank empty. You'd then be adding 7/8 of a pound additional with a full tank. STO(L) in that loading may be optomistic; though you don't HAVE to fill a tank just because it holds a certain amount.

sclitheroe

The recommended engine range is .40 to .60 for four stroke engines, so maybe I'm recalling the weight incorrectly - it might actually be 6-7 pounds all up weight. The plans don't call for a specific tank size, so that's why I'm asking. I'm leaning towards going with the 14oz tank, but not filling it all the way, especially not for a first flight.

-Scott