Questions tagged [airfoil]

The 2D shape of a section of aircraft wing.

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1answer
139 views

What happens when the velocity of the lower surface of the airfoil is lower than the velocity of the free stream?

At a certain AOA I noticed that the speed of air in the lower surface of the airfoil is lower than the free stream's speed. What is the consequence of that?
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1answer
613 views

How can I calculate stall speed using foilsim?

I need to find the stall speed of an airfoil using foilsim not the formula (https://www.grc.nasa.gov/WWW/K-12/airplane/foil3.html)
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2answers
696 views

Is flow turning different from the Magnus Effect? If so, how?

The production of lift is much more complex than a simple differential pressure between upper and lower airfoil surfaces. In fact, many lifting airfoils do not have an upper surface longer than ...
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2answers
771 views

How does the thickness of a wing affect its aspect ratio?

As far as I understand, the aspect ratio equals the wingspan divided by the chord or the square of the wingspan divided by the wing area. Given this formula factoring in only the wingspan, the chord, ...
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4answers
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Can this design provide more lift force than thrust from engine?

The problem is depicted in the picture: Generally, why we don't use engine blow wings to fly? Can we use wind-tunnel-like wing to generate lift force? Can it generate more lift than thrust? If it ...
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1answer
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What are the disadvantages (if any) of using a supercritical airfoil?

The title sums up my question pretty well. I've searched all over this site, having read many of the questions and answers to various supercritical wing topics, but I haven't found any mention of ...
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2answers
2k views

How to design the blade twist angle in propeller design?

I am designing a scale propeller for small UAVs and I have computed blade twist distribution for the blade airfoil sections. While I was modelling the propeller I have set the angles to twist about ...
13
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1answer
388 views

Can a transonic airfoil have two shock waves?

I am currently running CFD cases on a transonic airfoil at Mach 0.75 and performing an angle-of-attack sweep to evaluate its performance. When I reached the angle of attack of 4.5 degrees (which I ...
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3answers
9k views

What is the effect of flow separation on lift, pressure distribution and drag?

Consider an airfoil (a wing) in an airflow. When angle of attack increases, at some point the flow start to separate from trailing edge. By increasing the angle of attack more, this separation area ...
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0answers
204 views

Determination of a Joukowski airfoil chord (demonstration)

I'm currently studying Aerodynamics, and one thing that I noticed is that the maximum and minimum $x$ coordinate of the airfoils (which are necessary to compute the chord) on the transformed plane (...
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1answer
2k views

How to locate the coordinates of the Center of Gravity of an airfoil?

I am working on the inertial effects on a variable pitch propeller and i need to define the location of the center of gravity on the airfoil to calculate moments of Inertia and angular momentum. What ...
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1answer
1k views

What is the pressure on the pressure side in relation to the freestream?

The following [edited] images are from a network post: The top image states on the pressure side, the pressure is greater than the freestream. On the bottom image, the $C_p$ varies. According to ...
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2answers
2k views

Why use different airfoils on the same wing of an aircraft?

Why different airfoils are used in different portions of the same wing of an aircraft, for example Boeing 737 wing? Boeing Commercial Airplane Company model 737 airfoils' dat files from here: http://...
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2answers
2k views

How to calculate the drag on an airfoil from momentum equation (Fundamental of Aerodynamics 5th edition, J.D.Anderson)?

If you got the book, please read 2.6 section (page 135). Here is my sumary of this section: An airfoil in a wind tunnel (wingtips were butted against both sidewalls of wind tunnel). The control ...
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1answer
2k views

How to calculate variable pitch propeller parameters?

I'm carrying out a project on Variable Pitch Propellers for UAVs and especially self-adjusting or Passive Variable Pitch Propellers that change pitch due to aerodynamic forces and Pitching Moments. ...
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2answers
2k views

What is the meaning of the percentage used to describe the thinness of this glider's airfoil?

In a glider review for the Schempp-Hirth Discus, I encountered the following paragraph: The Discus 2 airfoil is thin (about 14.5 percent), incorporating studies by K.H. Horstmann and Dr. Wuerz (...
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Was the B727's wing supercritical (even if not so designed)?

The Boeing 727's wing upper surface appears unusually flat, especially at the root (Albeit at an angle). Refer to the images linked below: airlinereporter.com Flickr Also from Flickr Was the B727'...
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3answers
4k views

Why the dynamic pressure is not mentioned in the explanation of lift by Bernoulli's principle?

Usual "explanation" of lift using Bernoulli principle This theory is: Air over the wing is accelerated, its dynamic pressure increases with velocity. The static pressure over the wing decreases (due ...
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1answer
1k views

How to determine if flow transitions or separates from a Cp plot?

I came across this image: My question is: given a general Cp plot, how does one tell from the shape of the curve if flow transitions or separates? Specifically, what features on the plot do I look ...
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1answer
1k views

How to read the pressure diagram of an airfoil?

According to most authors, "lift is the result of the difference of pressure on airfoil sides". My question is not about how this difference is generated, but only about the representation of the ...
5
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1answer
299 views

What is the name of this airfoil?

Is there a general name for this type of airfoil? I'm having trouble finding any information on it so if anyone knows anything about it please let me know!
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1answer
7k 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 ...
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3answers
584 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 ...
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1answer
900 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?
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1answer
457 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 ...
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1answer
870 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 ...
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2answers
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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 ...
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1answer
629 views

How does airfoil thickness affect the Mach number at which it experiences transonic flow?

Roskam (book: Airplane Aerodynamics and Performance, Subparagraph: 2.5.2 HIGH-SPEED AIRSPEED INDICATORS (COMPRESSIBLE FLOW)) affirms: [...] Airplane with no sweep and thick airfoils become ...
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What are the correct names for the two faces of an airfoil?

When representing a wing airfoil, often the low pressure is on the top side and the lift is positive: In this case upper and lower sides are enough to understand the role of the surfaces, But this is ...
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1answer
498 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 ...
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1answer
875 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?
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1answer
636 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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434 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 ...
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1answer
17k 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. ...
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1answer
298 views

Where can I find articles about Handley Page multi element segmented airfoils?

Can anyone direct me to a source containing the complete article on Handley Page's 6 and 8 element airfoils from Flight magazine Feb 24, 1921 (PDF) or further more detailed information on this subject....
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355 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,
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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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3answers
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What software is used for aerodynamic wing shape optimization?

I can see lots of research articles around aerodynamic shape optimization of airfoils and wings like this MDOlab program. But all stuff like that don't seem to be available for a simple customer. ...
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1answer
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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 ...
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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 ...
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1answer
619 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?
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2answers
8k views

How does centre of pressure change with angle of attack?

I've been given the distance of centre of pressure from the leading edge with a certain angle of attack and was wondering if it's possible to calculate the new position when the angle of attack ...
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4answers
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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 ...
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1answer
547 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 ...
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3answers
8k views

Should the pitching moment be up or down?

I had a question regarding the direction of the pitching moment. To make sure we are on the same page, here is what I know so far (please correct me if I am wrong). Lift acts through center of ...
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Do airliners like Boeing and Airbus use airfoil variation along the span for their wings?

Airfoil variation will make a significant difference in airflow over the wing, thus proper variation according to the lift profile should improve the overall aerodynamic performance. But by how much? ...
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1answer
3k 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?
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1answer
286 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 ...
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1answer
309 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 ...
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1answer
751 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 ...