Questions tagged [airfoil]

The 2D shape of a section of aircraft wing.

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2answers
680 views

Why are cambered airfoils used for horizontal stabilizers in some designs?

From what I know, usually NACA9/12 or similar symmetrical airfoils are used for the tail. Still some aircrafts use highly cambered airfoils for elevators. What are some advantages and disadvantages ...
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1answer
395 views

What is wing trammelling?

What is wing trammelling and how does it affect wing stability and performance?
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2answers
739 views

What is the purpose of thinner airfoils used near wing tips?

I know that a thicker airfoil at root will strengthen the root spar but what is the reason behind using thinner airfoils at the tip? Is it because thinner airfoils have higher stalling angles of ...
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2answers
3k views

Why does the stagnation point on airfoil move with the angle of attack?

What is the physical explanation for the reason the stagnation point is where it is? And, why does it move further down the lower side of the airfoil with an increase in angle of attack?
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1answer
140 views

Are there multiple reasons for the decrease in pressure over a wing?

I'm aware that the decrease in pressure over the wing is due to the curvature of the airfoil which causes a pressure loss due to the spreading of the air as it is redirected. But is it also due to ...
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1answer
496 views

How does the position of the center of pressure change with the use of different high lift devices?

How is the position of the center of pressure affected by different high lift device deployments? My guesses are: When I use a high lift device that just increases the chord length, it moves ...
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2answers
709 views

What airfoil is used on the Lazair ultralight?

This is the airfoil of the famous Lazair ultralight. What is the name of this airfoil?
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1answer
4k views

Is it best to use a thick airfoil or an undercambered airfoil for slow speed flight?

The more the thickness,the more the frontal resistance,hence the more the drag a thick airfoil will produce. Under cambered can help increase lift without increasing the airfoil thickness , therefore ...
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2answers
172 views

Why flaps can deflect up to 25°+ without stalling the wings? [duplicate]

According to this graph,plain flaps have their highest Cl at about 2 and stalls at about 15°,my question is how then do airplane flaps reach 25°+ of delflection when this gragh clearly states that ...
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2answers
537 views

Would the Wright Flyer have flown better with thicker airfoils?

The Wright Flyer(s) flew with very little wing thickness,would they have flown higher, faster and longer if the wings had greater thickness? Secondly, how do thickness and camber affect a wing's ...
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2answers
2k views

Is airfoil thickness proportional to drag coefficient?

Does increase in the thickness of a camber airfoil mean more drag will be produced? Why do slow flying planes have thick airfoils when it will just slow them down even more?
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2answers
119 views

Is the lift produced by a wing with a 10° flap equal to the lift created by a wing with 10° AOA but with no flap?

After reading this article I would like to know if the lift produced by a wing with a 10° flap is equal to the lift created by a wing with 10° AOA but with no flap?
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0answers
86 views

What does “lower flatness” mean in airfoil terminology?

What does lower flatness mean in these parameters of a Glenn Martin airfoil?
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3answers
1k views

Aerodynamics of double winglets

I've read here on Aviation SE that the aerodynamics of winglets on an aircraft are easily described as "extending the airfoil". Thus, as I understand it, a winglet is like stretching the airfoil a ...
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1answer
774 views

What does leading edge radius mean?

What does leading edge radius mean amongst these parameters of a st cyr 24 airfoil?
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1answer
1k views

How to calculate Reynolds number?

How do I calculate the Reynolds number of a wing with wing chord,1.2m and speed of 60km/h
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1answer
162 views

Will I not be able to descend with an airfoil that stalls at -0.5°?

This stats says this airfoil stalls at -0.5°,does this means if I have this airfoil as a wing ,I won't even be able to have a descent aoa? !
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2answers
746 views

Winglet design and airfoil selection

I'm currently in the process of designing a winglet for my low speed aircraft in xflr. While researching about winglets I read in a Boeing article that if the baseline outboard wing is relatively ...
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2answers
684 views

Why is the critical AoA of most flaps 40° when most airfoils stall at 15°?

A plain flap deflected 40 degrees is largely stalled (...) Flaps stall at 40° according to an answer on Quora, why is this so when typical airfoils stall at 15°?
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1answer
460 views

Do elevators have cambered airfoils inverted or symmetrical airfoils

Do horizontal stabilizer of ga planes e.g cessna 172(or ultralights e.g lazair) have cambered airfoils inverted to provide the tail downward force or do they have symmetrical airfoils at negative aoi ...
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1answer
666 views

Where can I get a graph of lift coefficient against AOA for a symmetrical airfoil?

Where can I get get a graph lift coefficient against AOA for a symmetrical airfoil ? I am asking for a source or link to a graph or table of AOA against Cl of any symmetrical airfoil.
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1answer
683 views

What is decalage and how it affects airplane performance?

What is decalage in airplanes and how important is it in respect to airplane performance?
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1answer
4k views

How to select the most efficient airfoil for low speed flight?

What airfoil (or family) has the highest $C_L/C_D$ ratio at speeds in the $50\:km/h$ range. The use case would be an ultralight with a max speed of $50\:km/h$
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2answers
1k views

Is there a downwash equation?

I need to find an equation for the following problem: Suppose a full-size glider passes 10 feet over my head at high speed. No doubt I will feel the downward air pressure (downwash) caused by the ...
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2answers
5k views

Do negative angles-of-attack create lift?

(wikimedia.org) A typical curve showing section lift coefficient versus angle of attack for a cambered airfoil. Based on the graph above, do negative angle-of-attack values create lift? How?
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1answer
2k views

How is shear stress distributed on an airfoil?

I know the pressure distribution on an airfoil but not shear stress. How is shear stress distributed on an airfoil?
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3answers
1k views

What is the “Centre of Pressure”?

This question may sound naive but surprisingly it puzzles me. A wing has a centre of pressure, does it mean that lift acts on point and not on the whole chord of an airfoil?
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2answers
5k views

How to pick a good airfoil based on Cl and Cd

Let's assume I have 10 different airfoils graphs of Cl x Aoa, Cd x Aoa and Cl/Cd x Aoa. How do I pick the best one that will give me the most efficiency (the longest flight time)? I understand the ...
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2answers
511 views

How do we determine whether the airfoil trailing edge should be cusped or pointed?

I'm working on a project and I need to decide whether an airfoil has a cusped or pointed trailing edge given the x and y coordinates of the airfoil. What is the difference between the two trailing ...
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1answer
508 views

Do wingtip vortices cause a decrease in the lift component of aerodynamic force, and do planes need to pull more AoA to compensate?

So, from what I know about wingtip vortices, they shift the angle of the relative airflow to where the effective angle of attack of the airfoil is lowered. Since the aerodynamic force is always ...
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1answer
578 views

In what way are the airfoils used for a propeller different from the ones used in turbofan engine?

Airfoils are used in the blades of a propeller as well as the blades of the fan, axial compressor and turbine in a turbofan engine. Thus, the airfoils used in above two applications have different ...
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1answer
135 views

What are the effects of rotating airfoil sections to match wing's dihedral?

While designing a wing, what are the advantages and disadvantages of rotating the airfoil sections to match a linear dihedral (airfoil sections always perpendicular to the dihedral line)? Does the ...
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1answer
503 views

What would be the effect of skinning over the gap in fixed leading-edge slats?

The Zenith STOL CH-750 experimental aircraft uses a modified NACA 650-18 airfoil (having a 17% fatter-than-normal thickness) with a fixed leading-edge slat. In an effort to reduce drag and improve ...
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2answers
2k views

What are the effects of camber location in an airfoil?

Am I correct to assume that for a low speed aircraft, the location of the camber in the MAC's airfoil will correspond with the aerodynamic center? Also, does that affect the moment coefficient? And ...
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1answer
220 views

What are the equations of motions for parafoils?

I want to use the following equations so as to describe the motion of parafoil $$\left[ {\begin{array}{*{20}{c}}{\dot x}\\{\dot y}\\{\dot z}\end{array}} \right] = {V_a}\left[ {\begin{array}{*{20}{c}}{\...
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1answer
735 views

What is the mathematical relation between CLmax and Reynolds number?

I know that Reynolds number influences CLmax, but I am not able to find any formula with which I could plot a graph!
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1answer
5k views

Can I compute the lift coefficient based on the NACA airfoil?

I would like to know whether it is possible to compute the lift coefficient $C_l$ based on the NACA airfoil? Usually I look up the values on airfoiltools.com. Eg: If I have a 2412NACA airfoil and ...
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4answers
4k views

How do I choose the correct airfoil?

I am currently working on a personal single seat, piston aircraft that I would fly myself and I am currently in a bit of conundrum when it comes to my wing design. In this project, I assigned us in 2 ...
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2answers
5k views

How are empennage airfoils chosen?

Empennage airfoils are usually symmetric. What is the process behind choosing the airfoil used in the tail of the airplane? Is it related to the stability? And then how would the angle of attack of ...
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2answers
3k views

What are the conditions for an airfoil to be a “thin airfoil?”

I know about the theory differences between regular airfoils and thin airfoils, but is there any condition for saying a given airfoil can be analyzed as if it is thin? The extreme case of infinitely ...
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1answer
825 views

How does the airfoil pitching moment relate to center of pressure?

I've looked everywhere to find the answer and it's still unclear to me. How does pitching moment relate to center of pressure? Does it relate to coefficient of lift? I have made a carbon fiber wing ...
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2answers
13k views

How can I calculate the angle of attack of an airfoil?

Can someone provide me a general algorithm to compute the angle of attack of an airfoil, and some theory along with it?
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3answers
3k views

What is the physical meaning of circulation found in Kutta condition?

The Kutta–Joukowski theorem is applicable for 2D lift calculation as soon as the Kutta condition is verified. When this is the case, there is a circulation $\small \Gamma$ around the airfoil. My ...
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1answer
528 views

How to find coordinates of the geometric center of a NACA 4-digit airfoil?

For a project that my team and I are working on, we are using Autodesk Inventor Professional 2018 (student license) for 3D modelling. We are working on NACA airfoils. I need to create an airfoil ...
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2answers
399 views

Documentation about “drag stabilized flying wings using non-reflex airfoils”?

What provides lift is the wing, but it is unstable without one stabilizer. Flying wings airfoils, or reflex airfoils, carry their stabilizer inside them, through a reversed camber of the trailing ...
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2answers
608 views

Is inverted flight possible under these conditions? [duplicate]

My understanding of flight is that the primary aspect is the angle of deflection, and the purposes of the shape of the wing is to maximise efficiency. Could a commercial airliner with asymmetric ...
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1answer
2k views

Which are some planes shaped like an inverted wing?

To understand my question better, let's consider the priciple behind the lift generated by the wing - The upper surface of the air-foil is curved to deflect the air downwards using the Coanda effect. ...
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2answers
2k views

What airfoil design does the MQ-9 Reaper UAV use?

What airfoil design does the MQ-9 Reaper UAV use? Alternatively, what similar airfoil designs exist? I'm running simulations for the effects of vortex generators for a school project and I would ...
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1answer
267 views

What is the airfoil used in the SB13 flying wing?

(Source) What airfoil is used for the wing of this aircraft?
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1answer
305 views

Drag coefficient and lift coefficient [closed]

What happens if drag coefficient increases but the lift coefficient remain the same?