# Questions tagged [airfoil]

The 2D shape of a section of aircraft wing.

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### 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 ...
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 ...
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?
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-...
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 ...
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 ...
2k views

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 ...
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 ...
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 ...
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. ...
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 ...
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?
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?
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 ...
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 ...
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,
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 ...
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 ...
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?
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 ...
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 ...
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?
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 ...
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 ...
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 ...
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 ...
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 ...
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.
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 ...
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 ...
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?
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 ...
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 ...
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 ...