Aileron Thickness

[Bill Reed]

I am building a wot4 style model and about to put a TE on the wing. So I make the thickness pretty much what I want.

The ailerons are 5mm sheet, I read some where (cant find it with a search) that ailerons should be thicker OR thinner than TE.

Can anyone advise please? and does this apply to all styles of model?

Just trying to learn a bit

[wingcoax]

All models i have built have the ailerons matching the trailing edge. Its just like cutting a slice out of the trailing edge of the wing and hinging it.

[Don Fry]

Don't round the trailing edge. A sharp edge gives a clean and predictable breakaway of the airflow. You see all styles re thickness. I'm just putting together a Panic biplane. The ailerons are built up, but 6mm thick, front to rear, centre hinged onto a standard symmetrical wing.

[Bill Reed]

Don, Seen those Panics. When covered with the transparent stuff they look awesome. Go like crazy with a 61 that I see. The guy who had hit built it near perfect. He was a Avicraft regular so in the right place.

[Capt Kremen]

Interesting replies.

I have a American flight school book, ("Airplane & Radio Setup" by David A.Scott), which states do not 'bevel' ailerons but 'round' them. Also ... make the ailerons thicker. Author Mr Scott, who runs a long established R/C flight school and is also a qualified full-size display pilot, describes the advantages/theory of these actions. i.e, re-energize (US spelling LOL!) the airflow over the ailerons to maximise control authority and generate a linear control response. Also ... his 'Rule of Thumb' quote" Raise the aileron, elevator and rudder approx 1/16" each side - 3/32 to 1/8" thicker overall"

You can check out his Flight School books and download illustrated sample pages.

My 'flying field' experience, seal the gaps first and foremost, all the other ideas???? maybe/maybe not, my skills can't deduce any discernible improvement (or degradation!).

[Don Fry]

Capt, sounds like an idiot. You need a clean break. A rounded edge has not got a certain breakaway, and results in uncertain drag on the back of the wing. Sounds like he is stuck with 1950's aerodynamic theory. Remember those round backed cars. Then they went wedge shaped, as they still are.

i think I will put a Asp 75 in mine, trim it, and then slip an OS 91 FX in, same bolt holes.

Edited By Don Fry on 13/09/2019 18:38:47

Edited By Don Fry on 13/09/2019 18:39:27

[kc]

Presumably D.A. Scott was talking about the aileron hinged edge being rounded whilst Don was talking about the TE.

And I also think that Don was talking about the author of the book being an idiot not Capt Kremmen! ,

Edited By kc on 13/09/2019 18:59:46

[Don Fry]

KC is correct as ever.

[Capt Kremen]

Yep, that American was meaning 'Round(ing)' the leading edge of ailerons and also making them (slightly) thicker than the rear of the wing they attach to. As for sharp/straight trailing edges i.e. the very, very end edge of the T.E. taper, agree with Don.

Many an aerobatic type has a 'reverse taper' trailing edge, especially seen on rudders. This, it is suggested assists in preventing 'fishtailing' .... wiggle-waggle, wiggle-waggle!

Meanwhile Don, I hope I'm not an idiot but I think it's a brave person who doesn't admit they've never done some idiotic things in their time, even when flying model aeroplanes!

[Don Fry]

Capt, KC is right in all things. I didn't read your post well.

Mind, the concept of renergising airflow is much misused, and unless your man is describing a rounded front ended, embedded in a matching convex slot in the wing back edge, I can't see it being much different.

Also to be precise, a square edge is good, a knife edge is better. Can be done, but not easy on common or garden models.

[Robert Welford]

Posted by Capt Kremen on 13/09/2019 17:35:07:

Interesting replies.

I have a American flight school book, ("Airplane & Radio Setup" by David A.Scott), which states do not 'bevel' ailerons but 'round' them. Also ... make the ailerons thicker. Author Mr Scott, who runs a long established R/C flight school and is also a qualified full-size display pilot, describes the advantages/theory of these actions. i.e, re-energize (US spelling LOL!) the airflow over the ailerons to maximise control authority and generate a linear control response. Also ... his 'Rule of Thumb' quote" Raise the aileron, elevator and rudder approx 1/16" each side - 3/32 to 1/8" thicker overall"

You can check out his Flight School books and download illustrated sample pages.

My 'flying field' experience, seal the gaps first and foremost, all the other ideas???? maybe/maybe not, my skills can't deduce any discernible improvement (or degradation!).

I suspect the reason for making the thickness of the control surfaces thicker than the adjacent part of wing or tail is to trip the airflow and control the point at which the airflow becomes turbulent. This will give predictable transition to turbulent flow and give better control response and possibly reduce drag.

High performance full-size gliders trigger the the transition point just in from of the flaps and ailerons either by the use of zig-zag turbulator tape, or by using blown air holes. In this case the objective is to reduce drag.

[J D 8]

Made the mistake of having ailerons thinner than the trailing edge once, they just did not work until a lot of movement was applied.

With a new set same thickness as wing TE normal service was resumed.

[Simon Chaddock]

There is no one rule fits all in aerodynamics so the design of an aileron depends to a large degree on what you are trying to achieve.

In a glider drag is more important than control response whereas in an aerobatic plane the requirements tend to be the opposite.

Then throw in the degree of lamina flow and the effects of Reynolds number and the "best" design of any control surface is likely to come down to come down to what best suits your preference.

Personally I go for knife edged and fully sealed using a top tape hinge but then I am an ex full size glider pilot. .