Hey,

How big should the ailerons be on a flat bottom airfoil like the one used on telemaster? Depth (% of chord) and width (% of wingspan).

Cheers

For chord...... Don't go less than 10% of the overall chord. They usually write that as .10C. And you don't need to go greater than 25% of the overall chord for barndoor type ailerons.

For span........ If you go with the barn door type ailerons that're a major portion of the wing chord, you don't need to use more than 40% of the half-span when they are .25C. So for example, if your wing had a 10" chord and 60" span, those ailerons would be 2.5" chord with 12" span.

If you go with strip ailerons that're 10% of the overall wing chord, on that same 10"x60" wing, the strip ailerons would be an inch wide and wouldn't need to go more than 18". However, most everyone usually goes full span for convenience.

Keep in mind that with a cambered wing, it's sensible to rig the ailerons with differential. The one going up moves about 2 to 2.5 times as much as the one going down.

That is interesting info. I am scratch building a 60 big stick from plans and I have decided to build it with flaps to. Seeing that it is a scratch build it will be easy to change the design as I go. It will be about a 65 inch span and I plan to make the flaps about 10 inches by 2 inches and the ailerons the rest of the span [strip type as the original ,about 17.5 inches by two.What do you think of this plan,darock? These are thick wide wings and I bet it would still fly at 5 mph[with the flaps down]. What do you think ?

Ailerons on most aircraft only take up about 10% of the total wing area. Use darock's proportions, and you are into that range. Larger aileron area is found on aircraft that are more aerobatic. On some very small and very slow 3D-type models the aileron area is almost 50% of wing area. With slow speeds, you need large area for the control surface to be effective. Very fast models don't need large surfaces with large deflections to be very effective...witness pylon racers and jets.

Hey,

What are 'barn door type ailerons'? Are they just ailerons that use the outer portion of the wing, compared to the strip aileron alot of .40 size planes use (aileron goes from wing tip to wing root).

Cheers

Yes.
Evan.

Strip ailerons are typically 7 to 12% chord for trainer to sport models. Obviously the new 3D movement has taken this to extremes but that's a whole other deal.

"Barn door" or conventional outboard ailerons are from 15 to 22'ish% of the chord and from 1/3 to 1/2 span.

If you're looking at adding working flaps then going for the 15 to 20% option and just make the inboard area the flaps is a good way to go.

Hey,

I ended up building the ailerons .20C and about 45% half wing span. At the moment, my control throws are 25 degrees aileron up and 12.5 degrees aileron down.
Do i need more/less throw, or is what i have ok?


Cheers

Depends on what you want the airplane to do. Also, if the airplane is a Telemaster and going to be flown like most of those airplanes, you've maybe got about twice the deflection you'll ever use.

What you're doing really isn't going to have pat answers up front. You're simply going to have to flight test and go from the results. Do you have a picture of the airplane? There are a ton of variables that come into play. Like the wingspan. And maybe more important when wondering about aileron effectiveness would be the wing aspect ratio. And it'll still probably come back down to fly and try.

I've got a Sukhoi that'll snap stall with 15degrees of elevator. Fly a buddies 4star that won't stall with 45degrees. Way different airplanes and WAY DIFFERENT safety margins (CG to NP).

What you will probably find is that ailerons on a Telemaster look good, flap up and down, and the aeroplane still turns as well as ever with rudder. It's the wrong sort of aeroplane to effectivly use aileron for turn control. (Which is what we want the ailerons to do).
Evan.

ailerons on that plane are like a saddle on a sow
just link the rudder from th aileron channel and fly it - -it will work right
here is an example -my Seniorita - everyone flys it any mode as the thing just rolls into and out of turns in nice co ordination
ailerons CAN work on the std Telemaster but not as well as the rudder .