caleb

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I want to design a canard type airplane and I am looking for a good airfoil. Any ideas or airfoil numbers of canard airfoils. I know of a big site that has airfoil coordinates listed as well as .gif images I just need help with airfoil numbers. I was also curious on where the CG is? I think is is just ahead of the wing but does anyone know for sure? Thanks for your help,
Caleb

Mike James

To get one of these to fly well, you'll find that several things are unique about these airfoils and their interaction, and the CG. I'm not the expert, but there is some very good information on carnard aircraft, the forces involved, and their airfoils, in Andy Lennon's book, "The Basics of Model Aircraft Design".

If I had my copy here with me, I'd quote you some numbers, but it's loaned out. I do remember a factoid... The front (canard) airfoil set up to stall before the main wing, for reasons of stability. I believe you'll want semi-symmetrical airfoils for both main wing and canard.

The CG is indeed often in front of the main wing. (Depends on moment arms)

If you can get Mr. Lennon's book, (Model Airplane News has it, Barnes and Noble has it) it will answer all your questions, and then some.

Ollie

Not only must the stall angles of attack of the two wings be coordinated but the zero lift angles must also be coordinated. If the front wing goes zero lift before the aft wing, the plane will experience a violent nose down pitch. This can be very serious if caused by a gust when flying close to the ground or when attempting any negative G maneuvers. The airfoils and decalage have to meet unique requirements for a canard to be safe. Since each wing's stall angle depends in part on the aspect ratio of the wing, it must also be taken into account when selecting airfoils and decalage angles.

mobileraptor

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thought you might like to see my little canard. 40 size.