# Airfoil Design with XFLR5

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1. Oct 1, 2014

### BSids

Hey Everyone, so I have just started Aerodynamics and having completed a number of exercises I'm being asked to design an airfoil. I'm a bit outta my dept as Ive transferred into this course from a diff field.

1. The problem statement, all variables and given/known data
To design an airfoil, using the knowledge you've acquired in XFLR5, according to these criteria:

-2,000m
-0.8 m chord
-80m/s velocity
-Not too thin
-Operates close to stall
-naca 4/5 digit
-For help look at the Lockheed U2 example

2. Relevant equations
Okay so the information is a bit limited, considering I'm dealing with 2D airfoil, how do I know what is required of a high altitude aircraft? I've searched google for ages but info seems limited and the books are similar.
What type of values am I looking for in regard to the coefficients.

3. The attempt at a solution
I assume that I attain Mach Number and reynolds numbers using the usual equations and so can unput that into xflr. I've already completed exercises examining the effect of mach, reynolds no.,thickness and camber in regards to four digit naca profiles.

Thanks

2. Oct 6, 2014

### Greg Bernhardt

Thanks for the post! Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?

3. Oct 17, 2014

### stinsonbr

2000m is not considered high altitude. The U2 could fly above 21,000m, which then brings concerns over such low density air, but affected engine performance and control more than the type of airfoil (debatably).

I'm not familiar with the program you mention. Can you give more specifics into what it does, and what it requires? From the given data, the hardest part is probably going to be finding one that operates close to stall.

Definitely a good start to find density, Mach number, Reynolds, etc. Should all be fairly simple to find.

4. Oct 17, 2014

### rcgldr

Is 2,000 m the altitude (since 80 meters / second seems too fast for a 2 meter wing span)? "Operates close to stall" could apply to any airfoil if the amount of wing loading (weight per square meter) is high enough, but this isn't specified, and I don't know how you would specify wing loading for a 2d airfoil, so you could just choose an arbitrary angle of attack close to stall.