Questions tagged [airfoil]
The 2D shape of a section of aircraft wing.
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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
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?
2
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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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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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1answer
110 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 ...
3
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2answers
172 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
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
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 ...
5
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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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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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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'...
6
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1answer
227 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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0answers
32 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 ...
2
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1answer
124 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
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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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2answers
142 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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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 ...
2
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2answers
157 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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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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2answers
152 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 ...
2
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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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0answers
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
38 views
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 ...
3
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1answer
104 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 ...
3
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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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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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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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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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124 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
192 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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1answer
293 views
Why does the stall angle decrease as camber increases?
I have a rough idea about why $C_{{l}_{max}}$ increases with increase in camber.
But I can't explain why the stall angle decreases simultaneously.
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0answers
28 views
How to calculate the moment/torque at the center axis of a blade?
How do I calculate the moment/torque at the center axis (same plane with lift and drag force) of a blade with NACA airfoil standard when it is placed inside a wind tunnel or exposed to airflow?
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1answer
167 views
Is the highly optimized high subsonic cruise airfoil less safe for higher AOA flight? [duplicate]
An examination of the 737 airliner wing profile and that of a blue whale leads to the question of whether the high Reynolds number subsonic cruising airfoil and the low speed, high AOA airfoil are ...
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4answers
3k views
Why are the wings of some modern gliders tadpole shaped?
Why are the wings of some modern gliders tadpole shaped, rather than teardrop shaped? An example is the Schleicher ASG 29. Or did they just add a flat plate at the trailing edge for the flaps and ...
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0answers
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Why the lift and drag coefficients for the simulations differ from the experimental value?
I am doing CFD simulations for NACA Airfoil 2415 using K-Omega SST model on ANSYS fluent. I am using an tetrahedral unstructured mesh with 20 Inflation layers on the wall. I have been comparing my ...
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1answer
120 views
Do commercial passenger airplanes have cambered airfoils?
It seems to me that they logically would, since they have no need to fly upside down like an aerobatic plane would (so they would not need a symmetric airfoil for any conceivable reason). That being ...
2
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1answer
179 views
Do Alaskan bush pilots generate a Clmax of 5 with 90° flaps?
I understand the Alaskan bush pilots use 90° flaps in the Valdez STOL competition. I think this would stall the flaps. And if so, it wouldn't increase lift and reduce stall speed, but Javafoil says ...
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1answer
71 views
How can a NACA2312 airfoil or similar have a camber location from 30 to 39% without a change in airfoil name?
How can a NACA2312 airfoil or similar have a camber location from 30 to 39% without a change in airfoil name?
Was fooling around in javafoil, and noticed I could go from 30% camber to 39% camber, ...
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2answers
150 views
Shouldn't the upwash on an airfoil increase the effective angle of attack?
From what I understand, induced drag comes from a reduction of the effective angle seen by the airfoil.
However, from wind tunnel smoke visualization, we can see that the streamlines at the leading ...
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0answers
57 views
What is the reason for circulation of air around an airfoil? Based upon the circulation of air, why are airfoils shaped the way they are? [duplicate]
Foreword: I am an Aerospace Engineering student and next year is my third and final year, starting September 2019.
I was taught approximately 2 semesters ago that the correct theory of lift is that ...
