Questions tagged [airfoil]

The 2D shape of a section of aircraft wing.

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2answers
42 views

What type of airfoil do low-supersonic aircraft use?

I understand that supersonic airfoils have better performance supersonically, but it seems at if they are not always used for any aircraft that goes supersonic and that supercritical airfoils are ...
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1answer
122 views

How to find the static stall angle of attack for a given airfoil at given Re?

For vertical axis wind turbines applications I'm wondering how one would find the static stall angle of an airfoil at a given Reynold number? Is it just the critical angle of attach (AoA) where ...
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1answer
93 views

How does vorticity change the lift coefficient of an airfoil?

For airfoils in unsteady motion, the lift coefficient oscillates and the wake is characterized by vortex shedding. How does vortex shedding affect the lift coefficient for an airfoil?
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In the context of aircraft design, what are the differences between a flat plate shaped airfoil and a droplet shaped airfoil? [closed]

I am relatively new to aerodynamics and am curious to know what difference it makes on an aircraft - lift, drag, weight etc - which of the two airfoils is used on the wing.
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1answer
60 views

How do viscous drag and form drag individually change as a function of angle of attack?

Typically, when dealing with airfoils, the drag coefficient $C_d$ is given as a function of angle of attack. If we limit the discussion to 2D subsonic incompressible flows, then the drag is the sum of ...
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3answers
1k views

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
148 views

As you make a symmetrical airfoil thicker, in which direction does the lift force increase?

I am working on a project and just need to understand one concept that I cannot find an answer to anywhere and hoping you could answer for me. The project I'm working on is with airfoils and the main ...
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21 views

How can we find maximum lift coefficient of Airfoil?

I am trying to find the maximum Lift coefficient for airfoil NACA 64A-404. I chose this airfoil for wing. I am stuck at finding the Clmax. I tried to use javafoil but javafoil is showing Cl less than ...
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1answer
51 views

Does thin airfoil theory work at very high angles of attack?

Thin airfoil theory says that lift coefficient is directly proportional to the angle of attack in radians. I haven't been able to find any limit, short of stall, for applying this theory. It would ...
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2answers
179 views

Is there a database of airfoils for a given Reynolds number? [closed]

I'm trying to design my ultralight airplane. I know the basics of aerodynamics and airplane design, however, my question is if there are any tools (online, software, database ) that suggest the best ...
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1answer
87 views

How to reproduce NASA/Langley airfoils for general aviation with long chord lengths?

I have scaled a NASA/Langley LS(1)-0413 airfoil to a 90 inch chord length, and now the trailing edge is 0.5in. Any longer chord length would have a larger trailing edge thickness. (90in*(0.0071-0....
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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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2answers
174 views

Are larger airplanes more likely to stall?

Stalls happen when the boundary layer on top of a wing slows so much that it essentially becomes part of the airfoil. My question is, as the wings on larger aircraft present a longer flow path for ...
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1answer
375 views

What's the theoretical background of the critical angle of attack?

The critical angle of attack seems to be at all (most?) airfoils around 15-20°. Why is that? Why is it in this range and not lower or higher? Is it just the result of optimizing airfoils? Or is it ...
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1answer
38 views

Is the ratio of HP to weight constant for identical air frames of different sizes? (See Scenario)

In my head it seems logical that there would be a proportion between engine HP and empty weight. For example, the Wright Flyer weighed around 600 LBS empty and had a 12 HP engine. If I were to make an ...
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26 views

What happens to the dynamic temperature in the boundary layer at supersonic speed?

In the boundary layer for a supersonic flow, does the dynamic temp decrease? Thank you
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1answer
128 views

How accurate is XFoil / XFLR5 at 'kinda high' Reynolds numbers?

How accurate is XFoil/XFLR5 at Reynolds numbers between 2 million and 10 million? From my understanding it's only accurate at lower Re values.
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1answer
56 views

How to calculate pressure distribution over an airfoil from its coordinates?

I need to compute the pressure distribution over an airfoil (I have the coordinates, but any will do) with the streamline curvature method. Unfortunately, I cannot find much on the web. Can someone ...
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1answer
69 views

Why the gradient of $C_L$-$\alpha$ graph increases with the Mach number?

From the JAA ATPL Book 13 (Principles of flight) the gradient $\frac{dC_L}{d\alpha}$ of the $C_L$-$\alpha$ graph increases for higher Mach numbers. Can someone explain why this is the case?
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2answers
54 views

How is rotor airfoil analysis different than fixed wing airfoil analysis?

What the is difference between rotor airfoil analysis and fixed-wing airfoil analysis? Intuitively, it seems that the airspeed at the tip of a rotor blade would be more than that at its root. Wouldn'...
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2answers
145 views

How to increase payload capacity of plane?

Keeping thrust, wing span, weight (of plane) constant, can we increase the payload capacity (nearly 50% more)? Adding payload to plane, it decreases thrust/weight ratio, how does it affect the control ...
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1answer
229 views

Why is the pitching moment of this symmetric aerofoil non-zero?

As I understand it, the pitching moment coefficient of a symmetric aerofoil should be zero, under potential flow assumptions. Obviously, approaching stall and post-stall, these assumptions are invalid ...
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2answers
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Why are highly cambered airfoils rarely used in propellers or wings?

Highly cambered airfoils like the Seligs and Epplers are hardly ever used in propeller or wing sections. Why? Does their performance reduce at high Re? Are they only adequate at low Mach, low Re? ...
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34 views

How to calculate the mass moment of inertia of a symmetric wing like NACA-0012?

I am working on the pitching mechanism of a NACA-0012 wing. I have the mass and found out the centre of mass of the wing but the software (OpenFOAM) needs more parameters such as the mass moment of ...
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5answers
190 views

Can lift be increased by increasing the angle of incidence of the wing? [closed]

Can the lift of a plane be increased by increasing the Angle of Incidence (angle between the chord line of the main wing and the axis of the fuselage)? Meaning, can more lift be generated while the ...
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2answers
164 views

What are Uses of thin airfoil and thick airfoil?

I have heard that thin airfoils are used for fast fyling and thick airfoil a are used for more lift. Is it true? Can you explain specific uses of thick and thin airfoils ?
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1answer
125 views

Why do intermeshing helicopters use asymmetric airfoils?

I am referring to the Kaman K-max and the Kaman Huskie here. They both use NACA 23012, which is an asymmetric airfoil. Any reason as to why this is? Is there a different mechanic in play when ...
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52 views

How to choose airfoil for High Subsonic small UAV?

I am trying to make a concept for a small UAV. The UAV shall be flying at Mach=0.75 , shortly 0.9 For this, I am looking for an adequate airfoil, which allows me, to avoid Mach=1 on the airfoil. From ...
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1answer
76 views

The numerical method used by F.X Wortmann for inverse design

Apologies in advance for a long-winded question. Can someone who understands some airfoil theory and German language please help me understand the method outlined in this paper from Prof. FX Wortmann....
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1answer
110 views

F.X Wortmann airfoil naming convention

Does anyone happen to have a reference or such that explains the naming convention used by Prof. Wortmann for his airfoils? Usually it follows that for symmetrical ones, the first 2 digits are to ...
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1answer
119 views

What causes the vortex on the tip of this vertical stabilizer (CFD Simulation)

This is a computational fluid dynamics simulation of an airfoil that is oriented to look like a vertical stabilizer. After watching the video, it becomes clear that the tip of the stabilizer causes a ...
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3answers
161 views

Would a airfoil move backwards if you rotate it vertical

Lets say i have a wing with an engine attached to it like a propellor. And now i point the nose of my airplane up untill it is vertical. Would the wing still generate lift because of the air flowing ...
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1answer
162 views

Are there any NACA airfoils that resemble the X-29's wing?

As a part of my project, I am trying to perform structural and aerodynamic analysis of a forward swept wing on an aircraft, specifically the Grumman X-29 (pictured below). I am assuming that ...
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2answers
125 views

Vertical autorotation with passive rotor

Let's say we have a simple hollow cube(chosen for simplicity) with outside side length=10cm, thickness=5mm (or another arbitrary shape with arbitrary dimensions). Clarification: I am NOT talking ...
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1answer
623 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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2answers
154 views

Transonic Airfoil with high critical mach number

does anyone know, how I can find a transonic airfoil (high subsonic, Ma=0.88) with a high critical mach number? I know that if I know c,0,min = minimal pressure coefficient of the airfoil, then I can ...
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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? ...
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22 views

Where can I find wind tunnel pressure data for various airfoils?

I'm working on a simple panel method solver based on thin airfoil theory and I would like to validate my code using wind tunnel data. Is there any place where I can find pressure distribution data ...
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0answers
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What is the effect of wing flex on wing's airfoil shape and its performance effect on wing?

There are good amount of discussion on wing flex in this forum. I am more interested in understanding the effect of flex on aerofoil shape of the wing and its impact on flight performance. Do ...
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1answer
67 views

Turbulent flows over 6 series airfoils

6 Series Airfoils were developed to enhance the laminar flow region over the airfoil. But, the Reynolds number at which planes fly are high for the flow to be Laminar. Then what's point of introducing ...
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1answer
108 views

When calculating the lift coefficient, what area is used?

Lets say I had this rectangular double curve wing. Orange represents the chord length, red represents the airfoil outline length below the chord line, green represents the airfoil outline length above ...
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2answers
137 views

Why do airfoils in an airplane's wings have different shape and size along its span?

Why wings of an airplane consist of different shape and size of airfoil. What will happen if the thickness of wing are same throughout the wing?
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3answers
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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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2answers
1k views

Difference between symmetrical and cambered airofoil?

I have seen images of cambered and symmetrical wings but apart from that what are the major differences between them? I have also read that symmetric wings don't produce any lift at 0° AOA whereas ...
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0answers
44 views

How do I calculate the air pressure on the maximum bulge of the airfoil?

Picture 2: source. Consider I have an airplane and it wing, of course. The cross-section of the airfoil is as the picture 1. The leading edge and the wind direction are depicted there. The leading ...
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0answers
125 views

Are there any lift or lift coefficient equations which factor in the flap deflection angle?

I'm asking this because I tested a NACA 2412 wing with an adjustable flap in a subsonic wind tunnel and I'm getting the lowest Cl values for the highest flap deflection angle.. which to my knowledge ...
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1answer
7k 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 ...
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0answers
36 views

Where can I find data comparing coefficient of lift (and drag) curves for any airfoil with and without flaps deployed

I'm doing my masters thesis on a FISHBAC wing so I'm hoping to find coefficient of lift and drag curves for any airfoil with and without (any type of) flaps deployed (and preferably leading edge ...
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1answer
711 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 ...
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1answer
194 views

How much lift do supercritical airfoils produce?

Compared to your regular asymmetric cambered airfoil, How much does lift do supercritical airfoils produce?

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