Questions tagged [airfoil]

The 2D shape of a section of aircraft wing.

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2
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2answers
195 views

What's the theoretical background of the critical angle of attack?

The critical angle of attack seems to be at all (most?) airfoils around 15-20°. Why is that? Why is it in this range and not lower or higher? Is it just the result of optimizing airfoils? Or is it ...
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2answers
107 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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0answers
71 views

What kind of airfoil does airbus and boeing airplanes use? [closed]

What kind airfoils do Airbus and Boeing airplanes use? Do they use NACA airfoils or Clark Y airfoils or some other? And also please give me an explanation behind why they use this type of airfoil.
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3answers
7k views

Should the pitching moment be up or down?

I had a question regarding the direction of the pitching moment. To make sure we are on the same page, here is what I know so far (please correct me if I am wrong). Lift acts through center of ...
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1answer
94 views

Is there a database of airfoils for a given Reynolds number?

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 ...
2
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2answers
108 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
40 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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0answers
84 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 ...
9
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1answer
7k views

Does lift coefficient vary with the wind velocity for a given angle of attack?

I have this question in my mind. I have been trying to look for this in different books about aerodynamics and I couldn't find the answer. I know I could check the answer experimentally, if I had a ...
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0answers
33 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 ...
9
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1answer
652 views

Which books should I study to understand more about Supercritical airfoils?

I want to understand the theory behind supercritical airfoils and all the details about them. It would be nice if I could get a standard supercritical airfoil, its experimental Cl, Cd data in the ...
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1answer
165 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
93 views

Foil lift question as foil get thicker/taller

I am working on a project and just need to understand one concept that I cannot find an answer to anywhere and hoping you could answer for me. The project I'm working on is with airfoils and the main ...
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1answer
176 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
21 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
157 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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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 ...
8
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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
70 views

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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2answers
574 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
537 views

How does airfoil thickness affect the Mach number at which it experiences transonic flow?

Roskam (book: Airplane Aerodynamics and Performance, Subparagraph: 2.5.2 HIGH-SPEED AIRSPEED INDICATORS (COMPRESSIBLE FLOW)) affirms: [...] Airplane with no sweep and thick airfoils become ...
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3answers
3k views

Why the dynamic pressure is not mentioned in the explanation of lift by Bernoulli's principle?

Usual "explanation" of lift using Bernoulli principle This theory is: Air over the wing is accelerated, its dynamic pressure increases with velocity. The static pressure over the wing decreases (due ...
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0answers
77 views

Where can I find airfoil data for the Beechcraft 1900D tail?

I am creating a CAD model of Beechcraft 1900D from images for a project. So far most info is available in http://www.users.on.net/~grypen/b1900d.html except the airfoil used by the tails. I have ...
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2answers
353 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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8answers
3k views

Is there an aerofoil that gives reasonably good lift for both air flow directions: forward and backward?

Could an aerofoil be designed to give reasonably good lift for both flow directions? I was motivated by this related question on Aviation SE: Can a plane fly backward if its propeller is in reverse? ...
2
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1answer
108 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 ...
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1answer
233 views

What is the airfoil used in the SB13 flying wing?

(Source) What airfoil is used for the wing of this aircraft?
2
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1answer
165 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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2answers
4k 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
54 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
116 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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2answers
2k views

Which type of airfoil does the 737 use?

NACA airfoils are not used anymore except on some aircraft. So which type of airfoil does the 737 use? Which company designs it and builds it?
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2answers
444 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 ...
4
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3answers
326 views

What are the rules of airfoil thickness from root to tip on tapered wings?

I'm doing some research on wings and airfoils used in the 30s and 40s, and I'm trying to understand the rules about airfoil proportional thickness changes across the wing (root to tip) on tapered ...
2
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1answer
208 views

Would adding a slat and a slotted flap increase the max CL of a multi element airfoil to 6.5?

Would adding a slat and a slotted flap increase the of a multi element foil to 6.5? I understand, as a general rule, the max $C_L$ for a classic NACA airfoil is as follows: Base: 1.5 Slat: + 0.7 ...
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2answers
397 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 ...
2
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1answer
128 views

Where is the midspan airfoil located on the 737?

The 737 has a root airfoil, two midspans, and one outboard. Is the midspan located under the fuselage or between root and tip?
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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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0answers
52 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 ...
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1answer
85 views

What is the comparative roughness of fabric surfaces?

"The Design of the Aeroplane" by Darrol Stinton (1983) lists comparative roughness of aircraft skin material (pg 154). Unfortunately it does not list dope & fabric. What is the comparative ...
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0answers
54 views

What are the effects of endplate on airfoil section?

A 3D wing cannot achieve the same high lift/drag ratio (more than a hundred sometimes) displayed by a 2D profile (airfoil section). This is due to 3D effects like spanwise flow, wingtip losses(...
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1answer
160 views

Shock wave on airfoil

I was wondering the other day, during the trans sonic regime, when the velocity over the airfoil becomes supersonic,why does the shock wave standing on the airfoil moves downstream when the free ...
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2answers
170 views

What are the scale effects of GA wing tip airfoils?

[ update: I am adopting an improved description provided by Peter Kämpf: "...only looking at the airfoils in isolation..." ] The goal of this question is to determine if wing tip airfoil scale plays ...
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1answer
90 views

NACA Airfoil 0005.4

I have come across this NACA profile NACA 0005.4 mod and it is not clear how to interpret this airfoil. Is this considered a 4 digit NACA profile? What does the number after dot mean?
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2answers
275 views

How could I find 𝐶𝐿𝛼 lift coefficient slope?

I'm trying to find 𝐶𝐿𝛼 lift coefficient slope through the below diagram, could anyone explain for me please, how could I find it? by the way, I depend on this equation 𝐶𝐿 = 𝐶𝐿𝛼 (𝛼−𝛼0)
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1answer
39 views

How could I find the air velocity and lift force?

As shown below I have this information as shown below in the picture. I got the density according to the ISA standard 𝜌 = 1.225[kg/m^3] and 𝐶𝐿 = 𝐶𝐿𝛼 (𝛼−𝛼0) is calculated as below : α=−4: CL=...
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2answers
125 views

How can I tell from the location of flow separation if an airfoil is stalled?

I am in the process of completing a carbon airfoil for my track car (sedan) and I am looking to determine stall angle visually. AKA, wool tufts and highway runs with my GoPro pointed upward from the ...
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1answer
119 views

What was the Airfoil of Handley Page P.115?

This extreme sweptback delta was built to test the Concorde wing at low speeds, sources say it had a biconv 6% airfoil, but I failed in finding data about it.
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2answers
1k views

Do airliners like Boeing and Airbus use airfoil variation along the span for their wings?

Airfoil variation will make a significant difference in airflow over the wing, thus proper variation according to the lift profile should improve the overall aerodynamic performance. But by how much? ...
6
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1answer
1k views

Is drag coefficient lowest at zero angle of attack?

The drag coefficient of a symmetric airfoil is lowest when its angle of attack is zero. I'm not sure if this is true in general.