Questions tagged [airfoil]

The 2D shape of a section of aircraft wing.

Filter by
Sorted by
Tagged with
1
vote
0answers
84 views

What does “lower flatness” mean in airfoil terminology?

What does lower flatness mean in these parameters of a Glenn Martin airfoil?
3
votes
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 ...
3
votes
1answer
652 views

What does leading edge radius mean?

What does leading edge radius mean amongst these parameters of a st cyr 24 airfoil?
1
vote
1answer
158 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? !
4
votes
1answer
580 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.
1
vote
1answer
300 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 ...
3
votes
1answer
516 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?
3
votes
1answer
3k 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 $50\:km/h$
2
votes
2answers
1k views

What software is used for aerodynamic wing shape optimization?

I can see lots of research articles around aerodynamic shape optimization of airfoils and wings like this MDOlab program. But all stuff like that don't seem to be available for a simple customer. ...
2
votes
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?
4
votes
1answer
1k 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?
6
votes
2answers
4k 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 ...
5
votes
2answers
1k views

Is the Reynold's number a function of the fluid flow stream or the obstruction?

I am slightly confused with this notion of the Reynolds Number. Specifically, I am looking at airfoil performance at very low Reynolds number. I am reading a lot of papers saying things like ...
0
votes
1answer
194 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}}{\...
0
votes
1answer
412 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 ...
1
vote
1answer
424 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 ...
5
votes
1answer
441 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 ...
1
vote
1answer
127 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 ...
2
votes
2answers
1k 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 ...
2
votes
1answer
584 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!
5
votes
1answer
4k 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 ...
4
votes
3answers
3k 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 ...
3
votes
2answers
4k 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 ...
6
votes
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 ...
8
votes
3answers
13k views

What is the difference between a leading edge flap and a slat?

I always thought that the definition of slat was: "Lift modifying and adjustable wing element on the leading edge of main airfoil." and the definition of flap was: "Lift modifying and adustable ...
2
votes
1answer
681 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 ...
4
votes
2answers
11k 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?
14
votes
4answers
21k views

What is the performance of a flat plate wing?

By flat plate I mean this: Source: Physics.SE Low performance indeed, but how much low? How would: The angle of attack, The speed range, The turn capability, The fuel consumption, Or other ...
5
votes
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. ...
0
votes
1answer
300 views

Drag coefficient and lift coefficient [closed]

What happens if drag coefficient increases but the lift coefficient remain the same?
0
votes
1answer
127 views

What happens when the velocity of the lower surface of the airfoil is lower than the velocity of the free stream?

At a certain AOA I noticed that the speed of air in the lower surface of the airfoil is lower than the free stream's speed. What is the consequence of that?
5
votes
3answers
8k views

What is the effect of flow separation on lift, pressure distribution and drag?

Consider an airfoil (a wing) in an airflow. When angle of attack increases, at some point the flow start to separate from trailing edge. By increasing the angle of attack more, this separation area ...
0
votes
1answer
557 views

How can I calculate stall speed using foilsim?

I need to find the stall speed of an airfoil using foilsim not the formula (https://www.grc.nasa.gov/WWW/K-12/airplane/foil3.html)
3
votes
2answers
626 views

Is flow turning different from the Magnus Effect? If so, how?

The production of lift is much more complex than a simple differential pressure between upper and lower airfoil surfaces. In fact, many lifting airfoils do not have an upper surface longer than ...
2
votes
2answers
685 views

How does the thickness of a wing affect its aspect ratio?

As far as I understand, the aspect ratio equals the wingspan divided by the chord or the square of the wingspan divided by the wing area. Given this formula factoring in only the wingspan, the chord, ...
7
votes
1answer
2k views

What are the disadvantages (if any) of using a supercritical airfoil?

The title sums up my question pretty well. I've searched all over this site, having read many of the questions and answers to various supercritical wing topics, but I haven't found any mention of ...
6
votes
2answers
563 views

Which design method is used for super critical airfoils?

How is an Airfoil categorized as super critical or not super critical? What are the ways to design a super critical airfoils?
13
votes
1answer
342 views

Can a transonic airfoil have two shock waves?

I am currently running CFD cases on a transonic airfoil at Mach 0.75 and performing an angle-of-attack sweep to evaluate its performance. When I reached the angle of attack of 4.5 degrees (which I ...
1
vote
2answers
2k views

How to design the blade twist angle in propeller design?

I am designing a scale propeller for small UAVs and I have computed blade twist distribution for the blade airfoil sections. While I was modelling the propeller I have set the angles to twist about ...
0
votes
1answer
2k views

How to locate the coordinates of the Center of Gravity of an airfoil?

I am working on the inertial effects on a variable pitch propeller and i need to define the location of the center of gravity on the airfoil to calculate moments of Inertia and angular momentum. What ...
2
votes
0answers
185 views

Determination of a Joukowski airfoil chord (demonstration)

I'm currently studying Aerodynamics, and one thing that I noticed is that the maximum and minimum $x$ coordinate of the airfoils (which are necessary to compute the chord) on the transformed plane (...
4
votes
1answer
1k views

What is the pressure on the pressure side in relation to the freestream?

The following [edited] images are from a network post: The top image states on the pressure side, the pressure is greater than the freestream. On the bottom image, the $C_p$ varies. According to ...
7
votes
2answers
2k views

Why use different airfoils on the same wing of an aircraft?

Why different airfoils are used in different portions of the same wing of an aircraft, for example Boeing 737 wing? Boeing Commercial Airplane Company model 737 airfoils' dat files from here: http://...
0
votes
2answers
1k views

How to calculate the drag on an airfoil from momentum equation (Fundamental of Aerodynamics 5th edition, J.D.Anderson)?

If you got the book, please read 2.6 section (page 135). Here is my sumary of this section: An airfoil in a wind tunnel (wingtips were butted against both sidewalls of wind tunnel). The control ...
2
votes
1answer
2k views

How to calculate variable pitch propeller parameters?

I'm carrying out a project on Variable Pitch Propellers for UAVs and especially self-adjusting or Passive Variable Pitch Propellers that change pitch due to aerodynamic forces and Pitching Moments. ...
4
votes
2answers
1k views

What is the meaning of the percentage used to describe the thinness of this glider's airfoil?

In a glider review for the Schempp-Hirth Discus, I encountered the following paragraph: The Discus 2 airfoil is thin (about 14.5 percent), incorporating studies by K.H. Horstmann and Dr. Wuerz (...
5
votes
1answer
1k views

How to determine if flow transitions or separates from a Cp plot?

I came across this image: My question is: given a general Cp plot, how does one tell from the shape of the curve if flow transitions or separates? Specifically, what features on the plot do I look ...
3
votes
1answer
754 views

Are there any reference values for Cl and Cd of a NACA 0012 airfoil to verify CFD simulations?

I am having trouble finding the established results of inviscid flow CL and Cd variation over NACA 0012 airfoil, for the transonic region. I need the data to verify the results I am getting through my ...
5
votes
1answer
906 views

How to read the pressure diagram of an airfoil?

According to most authors, "lift is the result of the difference of pressure on airfoil sides". My question is not about how this difference is generated, but only about the representation of the ...
5
votes
1answer
295 views

What is the name of this airfoil?

Is there a general name for this type of airfoil? I'm having trouble finding any information on it so if anyone knows anything about it please let me know!