# Low speed airfoil

physicsCU
OK guys, I need some help.

I need to find a low-speed airfoil, about 30 mi/h.

the plane will only be like 12-14 lbs of takeoff weight.

just a basic airfoil or a source so i can get the drag.

Take a look at this report. Even though it is for high speed testing, you will get some NACA airfoil numbers that you can research for low speed applications. I would recommend looking for something with a decent camber on the top and a relatively flat bottom. A symmetrical wing is not what you are going to want if maximizing lift is what you are after. If all else fails and you can't find anything, take a look at basic R.C. airplanes at a hobby shop.

http://naca.larc.nasa.gov/reports/1935/naca-report-492/

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physicsCU
Thanks!

I was looking at something with a deep camber, but it doesn't matter yet, I am just trying to get a basic drag number from it.

sid_galt
physicsCU said:
OK guys, I need some help.

I need to find a low-speed airfoil, about 30 mi/h.

the plane will only be like 12-14 lbs of takeoff weight.

just a basic airfoil or a source so i can get the drag.

Just make sure the wing area is big enough.
E.g. if you take an eppler 61 as your airfoil, it has lift coefficients (2d) between 0.5-1 between angle of attack 0-5 degrees[1]. Taking 0.75 as the coefficient, 12 pounds = 5.44 kg as the weight, and 30 mi/h as the speed, the required wing area comes out to be 0.65 m2. The actual will naturally be larger.

Also the drag coefficient (2d) for the same is around 0.1[1] for the same angles of attack. If you calculate, the power required for flight comes out to be 117 W. Again the actual power required will be definitely larger. So just make sure you have a powerful engine.

Lastly if you haven't already, search for papers on MAVs on sites like scholar.google.com and thesis' on the internet. They help alot.

1 - Aerodynamic Measurements at Low Reynolds Numbers for Fixed Wing Micro Aerial Vehicles by Thomas J. Mueller.

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