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Old Jan 12, 2011, 01:58 PM
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Help!
Control surface size

How big should the ailerons be compared to the plane itself, as in 1/3 the length of the wing or what, and also how "deep" should they be? (Or you can just tell me how big it should be for a 500g, 50" wingspan plane)

Also, how much area should my elevators have?
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Old Jan 12, 2011, 02:47 PM
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For 3D planes, I've seen ailerons take up 40% of the wing surface. For sport planes, probably 10-15% or so.
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Old Jan 12, 2011, 03:05 PM
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Thanks rafe.

I'll try to fit 10% at least.
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Old Jan 12, 2011, 03:52 PM
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Laimis:

A few observations about ailerons you might want to consider.

Ailerons that are not the length of the wing:
  • Put them closer to the fuselage for a slow roll rate (think trainer types.)
  • Put them toward the wing tip for increased roll rate (think war birds.)

Ailerons that are the length of the wing, an Edge 540 for example:
  • Make them the length of wing if you want maximum roll rates (Think sport and 3D planes.)

Obviously longer and deeper ailerons will grab more air. Shorter and narrower ailerons will grab less and have less influence on the plane.

Chuck
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Old Jan 12, 2011, 04:04 PM
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Chuck, I understand the aerodynamics, I'm just wondering what kind of figures we're looking for.

How big do you people usually make elevators then?
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Old Jan 12, 2011, 04:12 PM
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laimis,

Check this out for the basics. You'll notice I said basics.

When you get into the more exotic Edges, Yaks, Sulkois, Sbachs etc...all bets are off.

Regards,

Hankg
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Old Jan 12, 2011, 04:34 PM
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Thanks! That gave me a good idea of what I'm looking for.
The only things I don't understand is what's an H-stab and V-stab.

Thanks again
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Old Jan 12, 2011, 05:11 PM
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Horizontal Stabilizer and Vertical Stabilizer.

Not sure if these terms mean just the non-moving part of the tail, or the moving (elevator and rudder) and non-moving parts.

Dave
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Old Jan 12, 2011, 07:04 PM
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Quote:
Originally Posted by CNY_Dave View Post
Horizontal Stabilizer and Vertical Stabilizer.

Not sure if these terms mean just the non-moving part of the tail, or the moving (elevator and rudder) and non-moving parts.

Dave
Hi Dave,

The non-moving parts. The moving parts are the elevator and rudder.
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Old Jan 12, 2011, 08:33 PM
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Aileron size usually depends on the roll rate needed and the speed of aircraft.
Also, it better to have a larger aileron with less throw, than a smaller one with a lot.
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Old Jan 12, 2011, 09:22 PM
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Quote:
Originally Posted by laimis350 View Post
How big do you people usually make elevators then?
If you're looking for a slow flyer, with docile roll rate, then Hankg's plan is in the ball park.

When I started to design and build my own planes I discovered the attached document. Very helpful. Author unknown. It's full of percents and ratios. The design of your wing is the starting point for the rest of the calculations. You start by determining how wide you want your wing to be then go from there.

Very interesting and easy to work with the ratios and percents on graph paper. I created several successful designs based on these ratios and percents. After that I started to take these figures and experiment.

See if the attached might be of interest to you.

Chuck
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Old Jan 12, 2011, 11:06 PM
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I don't know how I didn't guess H-stab and V-stab.
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Old Jan 13, 2011, 06:51 AM
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Don't know when it got changed but used to be just stab, short for stabilizer, which is what it does, and elevator. Vertical stab was called the fin, even easier to say, and the rudder. So, stab and elev, fin and rudder.

Gord.
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Old Jan 13, 2011, 08:31 AM
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DontTell,

That PDF is going into my documents file.

Regards,

Hankg
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Old Oct 07, 2012, 02:13 AM
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Thanx you guys, excellent information!
I started trying to fly and build stuff 5 months ago and had not specifically thought about an overall set of ratios for the airframe. but I have made at least one aircraft that flew without vices until I took control of the sticks!
I shall send anyone else here that I see asking similar questions. Thanx again.

I see my mum's designs have all but been forgotten about. She had a bunch of birch twigs at the back and a cloak and pointy hat at the front.
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