Questions tagged [airfoil]

The 2D shape of a section of aircraft wing.

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How to calculate lift and drag of commerical aircraft in different phases of flight?

What is the best way to mathematically calculate values of lift and drag forces, in different phases of flight: takeoff, climb, cruise, descent, and approach? Edit: I have the idea of calculating the ...
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Improvements in supercritical airfoil design from 1980 - 2000

I originally asked a question (Comparisons between the A340 and 747-200 wing: sweep angle and span) about the technological developments which allowed the Airbus A340 to have a wing with greater ...
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What naca airfoil is the closest to airfoils used by modern airliners?

I know boeing and airbus use propietary airfoils, but is there a single naca airfoil that is fairly representative of what modern airliners use?
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Converting 2d Cl to 3d [closed]

I am trying to convert 2d Cl data obtained from javafoil for a NACA 4412 into 3d data to be used for analysis of the airfoil, but cant find any equations online
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What is a "suction airfoil"?

I just stumbled upon this entry on airfoiltools.com: http://airfoiltools.com/airfoil/details?airfoil=griffith30symsuction-il There is basically no information there and (a quick cursory) web search ...
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What’s the horizontal and vertical tail airfoil and volume of 747-400? [closed]

What’s the horizontal tail volume coefficient of 747-400? What’s the vertical tail volume coefficient of 747-400? What’s the horizontal tail airfoil of 747-400? What’s the vertical tail airfoil of 747-...
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Never heard of this Aerofoil?

I just came across this aerofoil, 65-2xx? I searched this but it doesn’t come up with anything like 65-200 for example but instead SG6051 which is the closest I could find to this? Am I missing ...
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What airfoil is used for the Dash-8 Q400?

Can't find confirmed information, only one I found was here https://m-selig.ae.illinois.edu/ads/aircraft.html, an incomplete guide to airfoil usage...
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How reliable are the available airfoil data sources?

I am making calculations based on Blade Element (Momentum) theory (BEM) for propellers and I am trying to find the angle of attack at which the propeller performs most efficiently. If I have ...
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Is there an equation for how fast air accelerates into lower-pressure regions?

I’m designing a propeller, and I want to plan the shape of the trailing edge of each blade such that (as much as reasonably possible) the pressure comes out as an “equal” line. Thus - I'm wondering ...
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What is the airfoil of the Tecnam P2002?

Does anyone knows what airfoil is used on Tecnam P2002? I need it for my report but I can't seem to find anything from the internet.
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Find Cl from Cp values [duplicate]

i have a code of the panel method where I can calculate all the Cp values. my job is to calculate the Cl from these Cp values, and I understand that to do that I have to integrate the Cp over the ...
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The Effect of Pitching Moment on Aircraft Stability

I'm designing a small RC plane and I'm currently at the first iteration of airfoil selection. I have converged to Clark-Y, NACA-2412, NACA-2415, and S-8036. In comparing the four, I noticed that all ...
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How to solve normal and axial aerodynamic force coefficients integral equation to calculate lift coefficient for an airfoil?

$$ c_n = \frac{1}{c} \left[ \int_0^c (C_{p,l} - C_{p,u}) \, dx + \int_0^c \left(c_{f, u} \frac{dy_u}{dx} + c_{f,l} \frac{dy_l}{dx} \right) dx \right] $$ $$ c_a = \frac{1}{c} \left[ \int_0^c \left(C_{p,...
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On which point are the moment coefficients of the NACA airfoils measured? [duplicate]

On airfoiltools.com website, for example: NACA 2412, they give airfoil data. One of it is the moment coefficient of the airfoil vs the angle of attack of the airfoil. However, these moment data could ...
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Derivation of the axial force coefficient for an airfoil in terms of the pressure and skin friction coefficients

In chapter 1.5 of Fundamentals of Aerodynamics by Anderson, there is an expression for the axial force coefficient of an airfoil in terms of the pressure and skin friction coefficients. However, "...
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How can a small airflow that passes through a slots redirect all the outer flow?

If this is normal wing without slots behind wing will be huge wake; airflow will separate, which is very easy to predict. Why would the outer flow follow the wing's couture; how can a small airflow ...
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How to calculate the takeoff speed for a hypothetical aircraft?

Given some basic information such as: aircraft weight wing load (including wingspan, and basically the whole wing configuration) airfoil profile coefficient of lift angle of attack Is it possible to ...
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4 votes
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Is it possible to have a separated boundary layer without having reversal flow?

To fix the ideas, let's consider an airfoil instead of a generic shape. As far as I understand, the separation of the boundary layer takes place after there is a region of reversal flow on the suction ...
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4 votes
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Can I assume that aoa on horizontal stabilizers correspond to aoa of the main wing?

I am in the process of designing a small wing (Re ~ 50-100k) and am wondering if given (a) the Cm on the main wing is relatively small at low aoas, (b) the horizontal stabilizer will produce lift as ...
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Does wash-out reduce drag?

I am in the process of designing a small wing (Re ~ 50-100k) and was planning to "un-twist" the tip of the foil by -5°. This corresponds to the 5° aoa where the center part of the wing has ...
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How to turn inviscid data to viscous?

I have used Panel method to calculate Cp vs x/c graph and CL. But as panel method assumes attached flow it does not give an flow separation and thus in CL vs alpha graph I could not find any stall. My ...
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Why aren't HLFC panels mounted on wing?

I watched The Insane Engineering of the 787 by Real Engineering. He just gave short detail about the HLFC(Hybrid Laminar Flow Control) panel and mentioned their purpose isn't available online. I found ...
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What airfoil profile generates the greatest lift force for 0° angle of attack? [duplicate]

The profile is intended to be used as a flap - not as an aircraft wing, so consistent profile shape over the entire span. Is there any particular profile recommended for such use and at low speed air-...
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3 votes
3 answers
380 views

How do thick and thin airfoils compare in lift generation?

I find myself confused when comparing the lift generation amongst Thick and Thin Airfoils. A paper to which I have added reference below claims that thin airfoils are better in generating lift because ...
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9 votes
1 answer
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Why are there two local maximums on some CL vs AOA curves?

I know what a stall is but I don't understand why there are in some cases two local maximums on the $C_L$ vs AOA curve of some airfoils. What is the reason for the mini stall that occurs before the ...
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What is a laminar airfoil and what are their pros and cons?

I am wondering what is a laminar airfoil and what are their advantages and disadvantages if compared to other designs.
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Circulation around an airfoil at negative α

I was recently reading this very helpful string What is the physical meaning of circulation found in Kutta condition? and it explained very nicely potential flow around an airfoil. My question then is ...
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Does the A220-300 use supercritical airfoils in its wing?

I'm curious about whether or not this modern airliner uses supercritical aifoils in its wing, or just conventional NACA-style airfoils.
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What do these terms related to airfoils mean?

I keep coming across some terms related to airfoils and I'm not able to find clear definitions for these terms. Bubble ramps pressure recovery suction side
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Are empennage airfoils always symmetric in conventional airliners?

I'm specifically interested in these models: A319, B737-700, A220, E195-E2. You could call these conventional airliners, so I suppose the question is if these "conventional" planes have only ...
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Wing and horizontal/vertical tailplane airfoil type and relative thickness?

I've been searching for data on the airfoil type (namely if they are supercritical, aft-loading etc.) and relative thickness (average or in different positions) of the empennage (both horizontal and ...
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1 answer
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Servo-actuated aerofoil

I intend on calculating the the servo torque required to actuate a 75mmx38mm NACA0012 airfoil. The example at the end of the page in the link https://github.com/build-week/hover-jet/blob/feature/start-...
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How do i find a supercritical airfoil for my preliminary design?

The following information is available but i don't exactly know where to get the information about SC Airfoils from. Do Airbus , Boeing use secret airfoil that they don't disclose? Cruise Speed = 240 ...
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What is the relationship between the design lift coefficient and the section lift coefficient of a NACA5 airfoil?

I would like to know the relationship between the design lift coefficient Cli, of a 5-digit NACA airfoil, with the expression Cli = 0.15*L according to Wikipedia. And the section lift coefficient of ...
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Why doesn't Boeing use supercritical airfoils?

It's my first question & I really want to know the answer from professionals to decide if my new design of airfoil is worth it because the initial test by CFD software (Fluent-ANSYS) indicate that ...
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1 vote
1 answer
593 views

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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7 votes
3 answers
408 views

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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1 answer
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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 ...
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2 votes
1 answer
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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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2 answers
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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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2 votes
1 answer
370 views

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 ...
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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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2 votes
1 answer
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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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3 votes
1 answer
195 views

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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2 votes
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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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9 votes
4 answers
2k views

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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1 answer
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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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1 vote
1 answer
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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. ...
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