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Questions tagged [airfoil]

The 2D shape of a section of aircraft wing.

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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
620 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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4answers
151 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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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
176 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?
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1answer
75 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
110 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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0answers
60 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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29 views

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
118 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
55 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
333 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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1answer
65 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
92 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 ...
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0answers
37 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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3answers
81 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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1answer
98 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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4answers
3k 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 ...
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0answers
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airfoil design mean camber line [duplicate]

The mean camber line is said to be halfway between the upper and lower surfaces of the wing. However, it seems like it’s halfway through the chord line and upper surface. Can someone please clarify ...
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2answers
179 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 ...
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1answer
89 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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0answers
22 views

How is the inflow velocity distributed of a tilted and trimmed rotor in hover?

I'm wondering of how the inflow velocities per blade look during one revolution of a real-life helicopter in hover (no inflow velocity into the rotor plane) with a tilted rotor plane about 20 deg. Is ...
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4answers
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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
125 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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1answer
183 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
193 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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1answer
114 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
104 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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1answer
533 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
209 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
136 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 ...
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1answer
163 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 ...
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2answers
320 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
384 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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1answer
114 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 ...
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0answers
66 views

How does pitch moment affect load distribution on a wing?

I am to load test an airplane wing,how does pitch moment(Cm) comes into play or is it insignificant in relation to wing load distribution? St cyr 24 is the airfoil of the wings, at 10° Cm=0.07,how ...
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1answer
146 views

How do wing ribs withstand lateral lift force?

During roll,there is a vertical component of lift that keeps the plane in the air and an horizontal component that actually rolls the plane,how are wing ribs designed to help withstand this vertical(...
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1answer
109 views

How (or where) do I find an airfoil optimized for low reynolds numbers (100,000~150,000)?

Looking to build a RC plane. Because the span is going to be small and the speed relatively low, I estimate the R-number to be around 100,000. Is there an airfoil optimized for that range of Reynold's ...
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1answer
236 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
233 views

What is wing trammelling?

What is wing trammelling and how does it affect wing stability and performance?
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0answers
110 views

How do I find experimental Cp, Cd and Cl values for a NACA0012 airfoil? [duplicate]

How can I get experimental Cp, Cd and Cl values for a NACA0012 airfoil where Chord length=240mm and Re=4.6e5? I'm looking for both 2D and 3D airfoil/wing (infinite span). I understand that plenty of ...
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2answers
379 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
1k 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
138 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
188 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
374 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
1k 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
145 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
336 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
953 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?