Questions tagged [airfoil]

The 2D shape of a section of aircraft wing.

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4
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2answers
629 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
225 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
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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
66 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 ...
4
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1answer
104 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
116 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(...
2
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1answer
249 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 ...
3
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2answers
289 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 ...
1
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1answer
161 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
2k 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
56 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=...
3
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2answers
161 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
133 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
2k 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? ...
7
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1answer
2k 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.
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3answers
435 views

Why do modern aircraft have a slope on top of the airfoil? [duplicate]

I recently learned that the pressure on the bottom of the wing is increased, and air moves faster on the bottom part of the wing. The speed of the air on top of the wing is not increased. So I am ...
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4answers
1k views

Does an rc plane tail also have airfoil or is it just flat material? [closed]

I've chosen an airfoil for the wing, now i'm confused weather i should do the same for tail or just attach a flat piece of wood as tail. I'm going for conventional tail design. This is my first ever ...
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0answers
137 views

Is there a relationship between 2D airfoil aerodynamic results and a revolution body from that airfoil?

The airfoil would be symmetric and the axis of revolution would be its chord line. Edit1: To clarify the question, suppose we have a NACA 0010. Then, using for example XFoil, I'm able to get, for ...
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2answers
974 views

What is the difference between static and dynamic stall?

What are the static and dynamic stalls on the aircrafts wing? When would we encounter static and when dynamic one? What is the difference between them?
5
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1answer
309 views

Where can I find articles about Handley Page multi element segmented airfoils?

Can anyone direct me to a source containing the complete article on Handley Page's 6 and 8 element airfoils from Flight magazine Feb 24, 1921 (PDF) or further more detailed information on this subject....
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2answers
1k views

Why does a sharp leading edge result in a larger pressure peak?

I know in the real world the sharp leading edge (LE) will results in a larger pressure peak compared to a large radius LE. And that there are three types of stall. But I want the explanation in ...
2
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1answer
369 views

Why are hexa airfoils used on rockets despite having more drag that diamond airfoils? [closed]

I was doing a study on airfoils shape for a rocket. I tested the diamond and the hexagonal airfoil with Missile DatCom, RasAero and the Shock Expansion theory and from my results it seems like the ...
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2answers
775 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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0answers
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What is the relationship between the Center of Pressure and flap deployment?

I have been reading regarding the Center of Pressure of an airfoil (Cp) and the relationship with angle of attack. What is a good way to explain in layman's terms why the pressure changes in such a ...
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1answer
148 views

Anyone able to help identify what aerofoil this is?

Firstly, apologies for the potato quality of the image below. I am attempting to determine the qualities of a VTOL and cannot find any data online. If anyone knows what aerofoil this could be that ...
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0answers
85 views

What is subcritical and supercritical boundary layer?

What is subcritical and supercritical boundary layer? What is the difference between them?
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2answers
1k views

What is a rudder or fin stall?

What is a rudder or fin stall, how will the aircraft behave in that situation, and how should the pilot recognise it? What is the recovery procedure? And what is rudder reversal?
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4answers
2k views

Can this design provide more lift force than thrust from engine?

The problem is depicted in the picture: Generally, why we don't use engine blow wings to fly? Can we use wind-tunnel-like wing to generate lift force? Can it generate more lift than thrust? If it ...
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1answer
183 views

What airfoil type is used on the B727-200F?

What airfoil type is used on the Boeing 727-200F? Is it a NACA profile or something else?
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1answer
324 views

What to be considered in designing airplane tail (vertical and horizontal stabilizer, elevators and rudder)? [closed]

I would like to make a small amateur triplane with it maximum weight approximately 400 kgs with maximum speed 100 knots (180 kph). I have read many discussions about how to calculate the wing ...
7
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1answer
276 views

Why does strong shock wave-boundary-layer interaction produce a bubble reattachment?

The picture represents a lambda type shock wave, separating the boundary layer at its foot. Separation causes a recirculation bubble to appear. I understand why separation has happened, but what is ...
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3answers
161 views

Fabric-covered Clark Y Max Coefficient of Lift

I'm looking at the Aeronca C-3 Collegian, which had a Clark Y airfoil, and I'm finding the following: Wing area: 142 ft² Empty weight: 466 lbs Payload: 470 lbs Stall speed: 38 mph When I do the math ...
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4answers
4k views

Why isn't there a single best airfoil for subsonic flight?

Why does airfoil used by modern subsonic aircraft (this is true for transonic airliners too) vary from plane to plane? Haven't we figured out a single best airfoil shape, with the highest lift to ...
1
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1answer
567 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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4answers
1k views

Why does the aerodynamic center exist?

I am a glider pilot and instructor with a master’s degree in actuarial mathematics. I teach aerodynamics every winter for upcoming glider pilots. As you surely know, the aerodynamic center is the ...
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1answer
135 views

Is high speed buffet possible at supersonic speed?

Since high speed buffet is caused by boundary layer separation due to shock wave and at supersonic flight there is no shock wave directly onto the airfoil (it is attached to the trailing edge), is ...
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1answer
374 views

Circular arc airfoil wing: why does the wing nose down twist due to camber?

I am reading this paper: "Computational Investigation of Microscale Shrouded Rotor Aerodynamics in Hover" Vinod K. Lakshminarayan, James D. Baeder ; JOURNAL OF THE AMERICAN HELICOPTER SOCIETY56, ...
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1answer
481 views

the usage of thin airfoils for high-speed flight [closed]

what is The usage of thin aerofoils for high-speed flight I tried those answers:  They are perfect for controlling the local angle of attack, for instance in turbomachinery and flaps.  At ...
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2answers
2k views

Was the B727's wing supercritical (even if not so designed)?

The Boeing 727's wing upper surface appears unusually flat, especially at the root (Albeit at an angle). Refer to the images linked below: airlinereporter.com Flickr Also from Flickr Was the B727'...
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1answer
326 views

How do I choose the correct airfoil for my fast cargo UAV project?

I am not able to decide which airfoil to choose for my UAV project as I am confused. I need to lift a maximum of 100kg of extra payload excluding the aircraft's fuel and empty weight. Cruise velocity ...
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1answer
149 views

What is the function of a sweep cable?

This is Goat3 ultralight with sweep cables,what is the fuction of these sweep cables?
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2answers
668 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
3k views

Which airfoil would be optimum for a glider?

The glider I am designing has a mission requirement to fly for as much time as possible. It will fly in the low Re range of about 150,000 to 250,000. While comparing different airfoils I am looking ...
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1answer
516 views

What is the purpose of this span wise “false spar” on Affordaplane wings?

This is the wing of an Affordaplane Ultralight,what is the use of those spanwise foam boards between the foam ribs,I know it's not for aesthetics.
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0answers
261 views

How to transform a NACA airfoil into a near-circle using the inverse Karman-Trefftz?

Is there anyway to find the leading-edge's center of curvature of a NACA Airfoil? I'm trying to transform a NACA airfoil into a near-circle using the inverse Karman-Trefftz transformation. the ...
8
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2answers
609 views

Transonic buffet - reason for a rapid movements of the shockwave along the wing chord line?

I know that transonic aerodynamic buffet is caused by the separated turbulent boundary layer striking the airframe (horizontal stabilizer, wings, fuselage) with considerable force causing a high ...
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3answers
2k views

Why does a turbulent boundary layer cause more friction drag than a laminar boundary layer?

From what I understand, friction is caused by viscosity and a bigger Reynolds number signifies lower viscosity. Thus, a higher Reynolds number(i.e. turbulent flow) results in lower friction. But, ...
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2answers
910 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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3answers
4k views

Why should the leading edge be blunt on low-speed, subsonic airfoils?

I have read that is to help the flow remains attached, but I do not understand the physical principle.
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1answer
207 views

Airfoils designed for reverse flow [duplicate]

This question might seem strange as almost all aircraft have the air flowing over the wing in only one direction. However if you wanted to design an airfoil would have a good L/D in the forward flow ...