# Questions tagged [airfoil]

The 2D shape of a section of aircraft wing.

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### Reducing camber for DrelaGW19 for L/D ratio

Okay , Thankyou for letting me know But these airfoils (DrelaGW19 and GW27) have extreme camber on upper surface. Now why is that so? (The first reason could be good lift at high Reynolds number(~ 1.5 ...
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### What airfoil is used on the MQ-1B Predator's wing?

There are lot of UAV's in todays world to be re worked on. The General Atomics series of UCAVs is quite remarkable. I have selected MQ-1B Predator UAV, for an geometric analysis project(undergraduate)....
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### Why do X-wing configurations missile/guide bombs use symmetric airfoils?

From all the missiles/guide bombs I have come across, I've always observed that a symmetric airfoil is used for both the wing and tail. Why not have a cambered airfoil for the wing and a symmetric ...
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### Is it better to reduce drag or increase lift?

Essentially my question is, in general is it better to have a lower drag or a larger lift. I know lift to drag ratios are used as an indicator but I think these don't give the best picture. For ...
53 views

### How does airfoil affect the coefficient of lift vs. AOA slope?

I'm trying to understand whether the airfoil shape can affect the slope of Cl vs. AOA (coefficient of lift vs. angle of attack) in the "linear" portion, e.g., from a few degrees negative to ...
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### Swept back wing theory

I'm a beginner in airfoil design. I just came across swept-back wings. There is a point that I couldn't understand that theory. Why is the only perpendicular component of the airflow to the wing(...
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### Which airfoil to use for high subsonic flight?

I am desigining an aircraft, which shall fly up to Mach=0.9 in cruise flight in an altitude of 10 km. So when I think of which airfoil to choose, I have to consider aspects like max. lift coefficient ...
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### Why am I getting a low L/D of 4.3 for this supercritical airfoil in Autodesk CFD?

I am a high school student learning to analyze aircraft models in Autodesk CFD for the first time. My current project is analyzing a supercritical airfoil on Autodesk CFD (that was designed in ...
64 views

### What characteristic my canard needs to have when the canard also carries a pair of engine?

I am in 3rd year Aerospace Engineering and trying to do a preliminary design of an airplane. My design has a front wing that also has an engine at its root on both side of the fuselage. There is ...
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### Could leading-edge dynamic stall occur for a tripped airfoil?

As far as I know leading-edge dynamic stall is characterized by the formation of a Leading edge vortex. This leading edge vortex forms due to the 'bursting' of the LSB (Laminar separation bubble). ...
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### Why am I seeing extremely high L/D ratio of (e.g. L/D = 90) in my 2D airfoil analysis?

Can anyone explain/justify why, using the 'Theory of Wing Sections' by ABBOTT the lift/drag ratios seem so high. For example, I'm doing an analysis of the NACA0012 airfoil and using their experimental ...
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### How do I find the shear center of an unsymmetrical airfoil?

I'm quite a newbie of these systems and I am designing the wing box of a drone. I know where I want my shear centre. However, I have been trying to determine the shear centre of my idealized airfoil. ...
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### Are airfoil profiles patented? If not, why?

For something that takes so much research and can effect performance drastically, there seems to be no patents on airfoils. Too simple in appearance to patent? They appear simple at first but the ...
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### How do you calculate the optimal cruising speed of an airfoil?

I am working on a school project (aircraft design). I would like to know how to calculate the cruising speed of a given airfoil. For example, if I have a NACA 5613-35 airfoil (that is the NACA 4 digit ...
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### Calculating CL and CD from Cp vs. x/c graph data? [duplicate]

I need to calculate CL, CD, CM coefficients for NACA 0012 airfoil at angle of attack 6 degrees and Re=7.5e5, Mach=0.05. I used Xfoil for getting the CP distribution, Cp vs. x/c graph and Cp-x-y data. ...
105 views

### Lift Pressure Distribution [closed]

If the pressure goes always from high to low, we should have a compression, due the lower pressure of the air stream over the upper surface, and an expansion in the airstream in the lower surface. So ...
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### A question regarding airfoil parameters

If a hypothetical aircraft, which is a tailless straight flying-wing with no fuselage, has the following characteristics: moderate forward sweep an aspect ratio = 9 a dihedral angle of 3 degrees a ...
156 views

### Why doesn't the centre of pressure move in the case of a symmetric aerofoil?

Why doesn't the CP (centre of pressure) move in the case of a symmetric aerofoil? Also, why does the CP move backward in the case of a flat plate?
252 views

### How do I choose the vertical tail's airfoil?

I'm designing a fixed wing UAV and I'm having some doubts about how to determinate the vertical tail airfoil. It's important to say that we've already sized this surface. And till this moment we're ...
209 views

### Leading edge or trailing edge stall?

As I wrote last week, I'm doing a Benedek 10355 airfoil performance report. At this point of the work I am analyzing the stall of the profile at a fixed Reynolds number. The Benedek 10355 airfoil has ...
103 views

### Is it possible that as the Reynolds number increases, a laminar bubble increases in extension?

I'm studying the Benedek 10355 airfoil (Plot), which should be a profile used in air-controlled models. While I was carrying out a boundary layer analysis, I realized the particularity that I have ...
123 views

### Pressure distribution on Aircraft wing

While conducting a structural analysis FEA for an aircraft wing, I had to import the CFD pressures acting on the wing, lets say at an A.o.A = 10 deg, at 80 m/s and at sea level, and say the ...
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### 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 ...
583 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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### 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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### 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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### 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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### 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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### 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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### 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 ...
193 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 ...
43 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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### 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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### 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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### 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?