Questions tagged [airfoil]

The 2D shape of a section of aircraft wing.

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3
votes
1answer
565 views

Why is the numerically determined location of the center of pressure inaccurate near Cl = 0?

I am working on an assignment and I need to calculate the center of pressure of an airfoil, through a numerical method (the panel method). I am getting a weird result because it gives its position on ...
9
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1answer
714 views

Which books should I study to understand more about Supercritical airfoils?

I want to understand the theory behind supercritical airfoils and all the details about them. It would be nice if I could get a standard supercritical airfoil, its experimental Cl, Cd data in the ...
8
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3answers
3k views

Why should the leading edge be blunt on low-speed, subsonic airfoils?

I have read that is to help the flow remains attached, but I do not understand the physical principle.
4
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2answers
3k views

Which type of airfoil does the 737 use?

NACA airfoils are not used anymore except on some aircraft. So which type of airfoil does the 737 use? Which company designs it and builds it?
2
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1answer
257 views

What airfoil simulation software is suitable for a cut trailing edge?

I'm looking for a way to simulate airfoils used to reduce turbulence. airfoiltools.com already does this a long way. However I have width and length limits, and I'm interested in comparing full ...
9
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3answers
15k views

What is the difference between a leading edge flap and a slat?

I always thought that the definition of slat was: "Lift modifying and adjustable wing element on the leading edge of main airfoil." and the definition of flap was: "Lift modifying and adustable ...
-4
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3answers
412 views

Why do modern aircraft have a slope on top of the airfoil? [duplicate]

I recently learned that the pressure on the bottom of the wing is increased, and air moves faster on the bottom part of the wing. The speed of the air on top of the wing is not increased. So I am ...
3
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2answers
2k views

What is the best airfoil for Edge 540 Style Aircraft?

I need help picking an airfoil. I'm an artist and have limited knowledge of such things. It's for a game with an aircraft similar to an Edge 540 / Extra 300. Unfortunately I have a limited selection ...
3
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1answer
809 views

Are there any reference values for Cl and Cd of a NACA 0012 airfoil to verify CFD simulations?

I am having trouble finding the established results of inviscid flow CL and Cd variation over NACA 0012 airfoil, for the transonic region. I need the data to verify the results I am getting through my ...
11
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1answer
532 views

Why does linear airfoil theory break down at hypersonic speeds?

Why can't we just extend linear supersonic theory beyond M = 5? I've looked at NASA papers discussing everything from geometric effects, air disassociation, and thermal coupling, but no clear and ...
10
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1answer
8k views

Does lift coefficient vary with the wind velocity for a given angle of attack?

I have this question in my mind. I have been trying to look for this in different books about aerodynamics and I couldn't find the answer. I know I could check the answer experimentally, if I had a ...
2
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1answer
856 views

Why is this airfoil curved upwards on the bottom part of the airfoil?

Image source datawiki.net Is this to slow down airspeed. I know that the high pressure and low pressure above and below the wing both contribute to downwash, but how does this airfoil form downwash?
15
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4answers
23k views

What is the performance of a flat plate wing?

By flat plate I mean this: Source: Physics.SE Low performance indeed, but how much low? How would: The angle of attack, The speed range, The turn capability, The fuel consumption, Or other ...
-7
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1answer
2k views

How do the propeller blades accelerate air resulting in thrust to push an aircraft forward? [duplicate]

I do know that the blades on a propeller generate lift to provide a force pushing back on the air based on newton's law the 2nd. What I am having trouble understanding is how the blades generate ...
14
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3answers
15k views

Are NACA airfoils used in modern aircraft design?

I know that NACA is famous for its ducts: Gratuitous Ferrari F-40 from Wikipedia. Mmmm... pretty... It is also well known for its airfoils, and many planes in the early years of aviation used NACA ...
6
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2answers
5k views

What are the advantages of the B747-8 airfoil over B737's airfoil?

The Boeing 747-8 has a new airfoil design much different than a Boeing 737's airfoil. Boeing 737 airfoil: (source: How Airplanes Fly?) Boeing 747-8 airfoil: (source: Boeing) I am a little ...
26
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8answers
4k views

Is there an aerofoil that gives reasonably good lift for both air flow directions: forward and backward?

Could an aerofoil be designed to give reasonably good lift for both flow directions? I was motivated by this related question on Aviation SE: Can a plane fly backward if its propeller is in reverse? ...
6
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2answers
596 views

Which design method is used for super critical airfoils?

How is an Airfoil categorized as super critical or not super critical? What are the ways to design a super critical airfoils?
13
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2answers
25k views

What is the method to calculate a finite wing's lift from its sectional airfoil shape?

I am struggling to get my head around a concept that I believe should be fairly simple to understand. Lift versus drag and AoA data of many airfoils are freely available, for instance the NACA 4-...
11
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4answers
3k views

Why do airfoil's trailing edges point downward?

The trailing edge of and airfoil is mostly pointing downward. Is there any reason for that? Down wash increases drag and down wash is due to the direction of air pointing down. If the trailing edge is ...
10
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6answers
3k views

Why doesn't an airfoil rotate?

As far as I understand, two of the reasons how an airfoil generates lift are Coandă effect and downwash. However, if there is upwash near the leading edge, why isn't an airfoil rotated by the two ...
8
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3answers
4k views

Can a steady flow have stagnation points?

I am confused by this idea. If a flow is steady, its streamlines are unchanging. Taking the typical example of an airfoil, there is (at least) one streamline which will hit the leading edge of the ...
5
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2answers
2k views

Is the Reynold's number a function of the fluid flow stream or the obstruction?

I am slightly confused with this notion of the Reynolds Number. Specifically, I am looking at airfoil performance at very low Reynolds number. I am reading a lot of papers saying things like ...
5
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0answers
911 views

What are the locations on the Boeing 737 wing where the airfoil changes?

I would like to know where along the span of the 737 (let's say the NG) wing the two midsection airfoils are used. I am planning on running a CFD analysis of the 737 wing, and I need accurate data.
9
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4answers
5k views

How to go about designing a custom airfoil?

I am familiar with the NACA 4-digit and 5-digit airfoil design system where airfoils, but I was wondering if anyone had some good reference material or software for designing a completely custom ...

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