Questions tagged [airfoil]

The 2D shape of a section of aircraft wing.

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1answer
6k views

How do symmetrical airfoils generate lift? [duplicate]

It is widely understood that the curved shape of a typical airfoil (such as a Clark Y) causes a pressure difference that creates lift. How do symmetrical airfoils do this when the top and lower ...
3
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3answers
562 views

How do wing tip vortices interact with the airflow on an wing with winglets?

If winglets are added to an aircraft, do the vortices still interact with the airflow and create up wash and down wash. If the vortices do interact with the rest of the flow I am wondering how they do ...
3
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1answer
823 views

How to calculate the lift coefficient of a multi element airfoil?

How to calculate the lift coefficient of an airfoil section with flaps and slats if we know the Cl for the individual elements, like Cl of wing, Cl of slat and Cl of flap?
13
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2answers
22k 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-...
1
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1answer
434 views

How do KFm step airfoils work?

I was looking for airfoils, and I came across an interesting design. It's called a KFm1 step airfoil. Those of you in model aircraft design might have heard of it. However, I've never really seen one ...
3
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1answer
822 views

Did WWII fighters have inverted airfoils for horizontal stabilizers?

Like would for example the P-47 most likely have symmetric, normal or inverted airfoil as horz. tail? Is my analysis correct?: It has a CG at 25-32% MAC according to manual. Since AC on wings is ...
6
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2answers
2k views

Why are RC rotor blades different from helicopter blades?

Why do toy (RC) helicopters have curved flat surfaces and larger rotors on true helicopters have a solid aerofoil shape? If the rotor was mechanically strong enough to lift the desired weight, is ...
8
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1answer
471 views

Can a Kline-Fogleman airfoil be used for engine turbines?

I am currently working on the Kline-Fogleman airfoil for NACA 23015 variant at Reynolds number 208800 with the configuration of the backward facing step of 50% thickness at 50% chord on the bottom ...
4
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1answer
541 views

Is there any use for variable shape wings within aviation?

I am working on a variable shape airfoil which is originally intended for sailboats. However, I am wondering if there might be an application for such a design within aviation? The design I am working ...
6
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1answer
15k views

How do I choose the correct NACA airfoil for my requirements?

How do you find the correct NACA airfoil to use when you already know the requirements? All of the research I have done on this has shown how to determine what kind of camber/chord/aspect ratio etc. ...
6
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1answer
1k views

What are the correct names for the two faces of an airfoil?

Usual case When representing a wing airfoil, often: The lift is positive The upper surface is the one with low pressure. So the airfoil faces can just be called upper and lower surfaces and we ...
4
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1answer
748 views

Does the Airfoil Tools Cd/Alpha Curve include both induced and parasite drag?

I'm looking at Cd / Alpha for the SD7062 Profile: http://airfoiltools.com/airfoil/details?airfoil=sd7062-il Wondering if it includes both induced and parasite drag. How does one tell?
3
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1answer
564 views

Why are the aerodynamic characteristics of a finite wing different from the properties of its airfoil section?

Why are the aerodynamic characteristics of a finite wing different from the properties of its airfoil section?
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0answers
424 views

What is the best airfoil shape for maximum lift on flight path (angle of attack = 0)?

maybe my question sound's a little elementary. Is it possible to have an airfoil with considerable lift on flight-path (zero angles of attack)? If yes what is the best standard airfoil shape for this ...
1
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0answers
143 views

How is the chord length defined if the wing (whale flipper) is tapering like a wing and has a twist throughout the span? [duplicate]

Let me be more specific: I have a 3D scan of a whale tubercle. The tubercle is tapering and twisting along its half span. I want to find the mean chord length. Now let us say that my airfoil ...
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0answers
348 views

How do you determine the lift coefficient of a finite wing using the coefficient of an infinite one? [duplicate]

How assuming I know the lift coefficient of an airfoil/infinite wing, how do I then use this value to calculate the lift coefficient of a finite wing? Please quote your sources. Many thanks,
6
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1answer
1k views

How would an airfoil react if it was flown backwards?

Out of curiosity what would happen? Would pressure on both top and bottom flip? or stay the same or act as a normal wing with less lift? I'd assume it would still take longer to travel over the top ...
3
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1answer
2k views

How to read representations of pressure around an airfoil?

Actual representations found online I selected 6 online representations of pressure around an airfoil, mostly using inconsistent symbolization of the pressure field. Source of the individual ...
2
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1answer
565 views

How to calculate airfoil geometry with the maximum lift to drag ratio for a given Reynolds number?

How does one determine the optimal cross sectional geometry to maximize Cl/Cd?
55
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4answers
10k views

Why do solar planes have many small propellers instead of fewer large ones?

Many solar planes, like NASA's Helios (pictured above), NASA's Pathfinder, and to a lesser extent Facebook's Aquila employ the use of many small motor propeller sets instead of one or two engines like ...
7
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2answers
4k 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 ...
-1
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1answer
2k views

How can I calculate airfoil thickness?

Given this information... ... how can I find the thickness for a "NASA/Langley LS(1)-0417MOD general aviation airfoil" at 90% and 99% chord?
2
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1answer
248 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 ...
2
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1answer
268 views

How are wingtips attached to the aerofoil while maintaining structural rigidity?

I've been trying to research various methods on the joints between the winglet and the wingtip out of interest. I'm aware that the airfoil is attached to the underbody of the fuselage by means of a ...
2
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1answer
260 views

Where can I find the aerofoil geometry of a commercial aircraft so as to design it in CAD software?

As a part of my final year thesis, I need to design a commercial aerofoil for an existing aircraft (such as Boeing/Airbus) to conduct some FEA & CFD analysis. I've been trying to source aerofoil ...
3
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1answer
485 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 ...
8
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1answer
700 views

Could the Concorde reliably land with all engines out?

The Concorde was designed to fly at supersonic speeds; because of this its delta wings produce more drag at subsonic speeds. My understanding is that delta wings can produce a large amount of lift at ...
5
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0answers
899 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.
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 ...
11
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1answer
505 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 ...
2
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1answer
802 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?
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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 ...
13
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3answers
13k 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 ...
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 ...
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 ...
9
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4answers
4k 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 ...