Sailplane control surface sizing...

[skyzking]

Hi everyone,

Does anyone know of a good article or website in regards to the size of control surfaces on rc sailplanes. Im currently designing one and would like an expert opinion on the size of primary controls and some secondary controls (especially flaps).

Thank you,
Abdullah...

[eflightray]

No way am I an expert, but this site should help - Glider Aerodynamics (http://www.gliders.dk/aerodynamic.htm), but I would think it's unlikely that there is any formula for control surface sizing.

It could depend a bit on what type of model, and what was expected of the models flight pattern, (thermal soaring, slope soaring, aerobatics, dynamic soaring, HLG, etc).

[eflightray]

There is also The Lift Zone (http://www.liftzone.com/) (advertised top right of RCGroups), they are more glider specific.

Here's a good site on many commercial gliders, Fatlion Gliders/Soaring (http://fatlion.com/sailplanes/other.html) also if you scroll down to the 'Links' on the left hand side, there are plenty of them.

[JetPlaneFlyer]

I'd find an existing successful glider with similar specification to that which you have in mind and copy control surface sizes from it!

Not very scientific i know :o

Steve

[fnev]

The following is not EXACT science, but it should help!

First of, all in general, a profile comes with it best point to articulate a control surface (i.e. an elevator, an aileron/flap, etc). For the “older” wing section it is usually around 20 to 25%. For a modern profile it is generally between 15 to 22%. If it is for a high performance wing it is critical to use the right value. But the influence of the quality of the hinge and the respect of the geometry is most of the time way more critical.

Secondly you won’t go wrong if the area of the aileron is 1/10th of half the total wing area. This should be combined with an aileron length of roughly ¼ of half the total span (unless it is a full span aileron). Be careful: the aileron should NOT go all the way to the wing tip. It would be wise to leave a distance equivalent to the tip chord or less (at least half the tip chord) for a clean flow around the wing tip and to minimize tip stall.

The rest of the trailing edge can be used for flaps. Depending on the span it would be better to stop the flap inboard 1 to 2 inches from the fuselage.

[Flight Engineer]

calculators (http://cmreel.com/?page_id=737)

calculators here.

[skyzking]

Thanks to everyone for their help...