Adding flaps - proportions needed please
 

Hi guys,
Hopefully this should just be a quick question for you experienced people ;)

I want to add flaps (specifically for landing) and I was just wondering what percentage of the wing(s) they should be. In an English magazine I saw a figure of 20% chord and 30% span - does that sound about right? The original model was/is designed with full length ailerons so will the remaining 70% span ailerons still be o.k. (it's a 'stick' design)? Increase aileron chord to give original area or just wind up the throws a little?

Thanks!
Steve

RE: Adding flaps - proportions needed please
 

20% chord/30% span are reasonable numbers.
The remaining surface for ailerons will be -more- effective, as the centroid of the area has been further from the fuselage, increasing the moment arm of the aileron. You will not notice any degradation in roll response.

RE: Adding flaps - proportions needed please
 

You can size the flaps smaller or larger... depending on how much effect you want. the 20% chord X 30% span is pretty close to scale for a Cessna 182. There are full scale designs with somewhat less flap area, and there are many designs where actuating the flaps can nearly double the wing area, such as on most modern airliners.

"Playing with" assorted flap designs on the models can be interresting. ;)

How you hinge them can make a lot of difference in how they make the model respond. Hinging the flaps below the bottom of the wing and a little behind the place the flap meets the fixed surface makes the flap rotate back as it deflects down and the LE of the flap is raised. This is a "sort-of-fowler" method that is easy to do and generally gives good results.

The simple method of cutting the ailerons 70/30 will work well. (especially if the hinges are already placed right for the modification) But you don't HAVE to do it that way. [8D]

RE: Adding flaps - proportions needed please
 

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RE: Adding flaps - proportions needed please
 

Here's quite a bit of info on flaps, slats, spoilers, etc., largely contributed by RCU members.
http://homepage.mac.com/mikejames/rc...ite/index.html

(Always looking for new contributors, by the way.) This is free, and if you contribute, I will credit anyone who contributes appropriately as the author.

RE: Adding flaps - proportions needed please
 

Here's a great source of modeling information that I should have suggested... Check it out!
http://www.angelfire.com/indie/aerostuff/index.html

RE: Adding flaps - proportions needed please
 

Thanks Guys! Great info and much appreciated, Mikes links especially!