Questions tagged [airfoil]

The 2D shape of a section of aircraft wing.

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29 views

Designing a lightweight remote controlled glider: optimal wing configuration and geometry [closed]

So here’s a summary: we need to design a remote controlled glider that will drop a load (golf ball) on a target. The load’s drop needs to be slowed down (ex: parachute). The glider must be very light (...
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Why are birdlike airfoils not used?

Here are two airfoils (lets focus on Re 100,000): SD7043-il which is simple to build and has a glide ratio of about 60 e376-il a birdlike and much harder to build if using paper or similar due to the ...
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1answer
46 views

Is lift/drag the same as coefficient of lift/coefficient of drag?

I see it being used interchangeably (for example by Airfoil Tools Fusion360 AddIn), so can I just pick an airfoil from the airfoiltools database with a certain CL/CD for my aircraft and assume L/D is ...
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122 views

Why is the aerodynamic center for most airfoils located at the quarter chord location?

I've been reading several sources on the location of the aerodynamic center https://web.mit.edu/16.unified/www/FALL/fluids/Lectures/f03.pdf https://en.wikipedia.org/wiki/Aerodynamic_center John ...
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1answer
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Why does my wind tunnel experiment give two different stall angles of attack?

When I increase the angle of attack from 0 to 20 the stall begins at 18 deg. When I decrease the angle of attack from 20 to 0 the stall ends at 13 deg. Why the difference and what value (13 or 18 deg) ...
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191 views

Would this quadrilateral-shaped airfoil produce lift with a zero angle of attack?

I have been recently studying the shapes and characteristics of different high-lift airfoils that have been used for VTOL aircrafts. While studying these different designs today, a particular ...
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3answers
164 views

What is the impact of camber on CLmax?

I was reading Aerodynamics for Engineering Students by Houghton and saw the following graph: A lot of other sources say that increasing camber increases CLmax, like the graph below. I am a little ...
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1answer
73 views

On an aerofoil or circular cylinder why does the airflow stay attached after passing the point of maximum thickness?

Why does it follow the curvature rather than separating? Its not due to the coanda effect as the accelerated flow near the surface of the aerofoil can't be considered a jet. It's not due to surface ...
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1answer
50 views

Comparison of pitching moment at different locations

I've conducted some numerical simulations of a pitching airfoil at three different locations of the pitching axis along the airfoil. The locations (from the leading edge of the airfoil) are: $0.25c$, $...
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1answer
47 views

Can an airfoil have multiple aerodynamic centers?

Aerodynamic center is a point where the moment is independent of angle of attack. Can we have 2 or more such points? Does it necessarily lie inside the airfoil?
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Which among the two contributes most of the lift, the upper or lower surface of the airfoil? [duplicate]

I see some explanations that lift is due to the suction of low pressure on the top surface of the wing and deflecting down of airflow on the bottom which results to upward force lift. I wonder, which ...
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224 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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132 views

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
103 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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63 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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27 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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74 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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1answer
165 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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2answers
177 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
40 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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28 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
61 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
71 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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1answer
97 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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2answers
69 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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298 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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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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1answer
227 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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2answers
2k views

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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2answers
213 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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197 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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291 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
154 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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53 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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98 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
153 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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3answers
163 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
173 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
139 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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2answers
203 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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1answer
122 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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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
70 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
143 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
145 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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227 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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2answers
2k 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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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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140 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
213 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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