desert aardvark

I just put together an Aquila Speed (Scorpio Kit). There is no reference to setting the stabilizer. The wings have positive incidence. My question is should the stab be set relative to the wing incidence? If so, what would that relationship be?

Lost in the Desert

Tall Paul

Set the horzontal horizontal... relative to the fuselage reference line.. with a flying tail, you iwll trimm it to the proper angle after you fly it a couple times.
A good starting angle would be to place a straight edge on the -bottom- of the wing, and set the horizontal parallel to that.
Possibly trim in a bit of up for the first toss.. be ready to push the nose down.. otherwise fly it and see where it wants the horizontal to be.

desert aardvark

Thanks for your reply. There is no reference line on the fuse to work with. My only reference is the wing. Should I set it at the same incidence as the wing, and give it a try?

Tall Paul

No, do it this way.. setting the tail at the same angle as the wing is putting down elevator into the horizontal.

BMatthews

It's tough setting all flying stabs.

Paul's sketch is a good starting place. But take note of the fact that if the wing has a lot of built in incidence then the elevator WILL look like it's trimmed too far down. The old Hobie Hawk is a prime example of this.

I also suggest you do some run testing with the model. Hold it over your head with a light thumb and two finger grip at the balance point so it sits level in your light grip. Then run into the wind and feel for the model wanting to try to pitch up or down. If you run fast enough or the wind is strong enough the model should feel lighter in your grip than when still but not try to lift out of your grip. Adjust the elevator trim and re-test until it feels like that. Once set it's time for the first high start launch or proper test glide into the proverbial tall grass.

I've done a number of models that way now and it's gotten me close enough to the proper setting that the first test flights only needed a few clicks of trim either way and totally avoided any heart wrenching surprises.

sackie

Hi all, I am just about to set up my first glider as well but not my first RC aircraft. My glider is an Airtronics Sagitta 900 and it too has a flying stab and what I wanted to ask is how much angle (maximum up and down) should I have. The approximate distance between the pivot of the stab and the CG is about 28 ins. The stab on a Sagitta is somewhat up the fin not at the base and not at the top as a T tail. Any assistance/recommendation is greateful.

Andrew

Tall Paul

You don't want or need a lot of deflection with a flying tail. 15 degrees may be all you'll need.
With dual rates, it's simple to have two deflections available..Use the lower value for the first flight's launch. The higher value reserved for landing. Then adjust as flying indicates.

sackie

Many thanks for your reply Paul.

Sackie

ptb

I probably go about it backwards,i put a straight edge on the horizontal stabilizer
pointed toward the wing, and measure the diferance between the leading edge and the trailing edge, and add alittle bit of positive incidance, for a starting point.