# Questions tagged [aerodynamics]

Aerodynamics is the study of how air moves and interacts with solid objects. It is an essential part of aircraft design.

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### Temperature profile for a boundary layer

So I was reading the textbook today, and I see this picture for the temperature profile through the boundary layer. And I was confused on why the shape looks like this? Should it not look more like ...
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### How to calculate lift and drag of commerical aircraft in different phases of flight?

What is the best way to mathematically calculate values of lift and drag forces, in different phases of flight: takeoff, climb, cruise, descent, and approach? Edit: I have the idea of calculating the ...
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1 vote
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### Why can't supersonic flow work its way upstream?

I am reading this textbook today. And it described supersonic flow as follows: In a supersonic flow, because the local flow velocity is greater than the speed of sound, disturbances created at some ...
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### Why does the leading edge vortex accelerate the flow downward?

I know leading edge vortices over delta wings make more lift. I understood that the core of the vortex sheet is low, so there is suction flow that makes lift. But, I can't understand how a leading ...
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1 vote
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### What is the purpose of the small vertical dorsal fin about halfway along the fuselage of the Boeing 737? [duplicate]

I've searched for an answer to this question on this site and others: What is the purpose of the small vertical dorsal fin about halfway along the fuselage of the Boeing 737? See the attached image ...
1 vote
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### What does deploying landing flaps do to the (L/D)max and minimum drag speed of an airplane?

I thought that deploying flaps will increase both the drag and lift, thus increasing L/D ratio? But do they increase proportionately? And how exactly does that correlate with the increase/decrease of ...
1 vote
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### Change of absolute ceiling with weight

Let's say an aircraft has an abs ceiling of some value at the start of its cruise and then it consumes some percentage of its fuel during cruise. How will this change the new abs ceiling at the end of ...
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### Aircraft pitch and AOA change during a coordinated turn maneuver

Let us say I am flying a constant airspeed turn while maintaining my altitude, when I enter into the turn, lift has to be increased and since airspeed remains constant, the AOA has to be increased to ...
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### Can an encapsulated airfoil generate enough lift to lift the capsule?

Can an airfoil generate enough lift, if it is contained in an enclosed space, to lift the enclosed space? Assume that there would be sufficient airflow over the foil to generate lift if it was not in ...
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### how is ITT peak temperature affected by altitude during an airstart?

another T-6 Texan II (turboprop aircraft) question. When reading the airstart prodedure in the engine failure during flight section of the manual, I found something that Id appreciate the ...
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### Has there ever been a VTOL aircraft thruster that generated lift through the use of a drag force?

I have been recently thinking about a conceptual VTOL aircraft thruster that should generate lift through the use of a drag force and I am very curious to know if such a thruster has ever been built ...
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### How does the weight affect the altitude that can be reached by trading speed after a total engine failure?

I recently read in the manual for The Beechcraft T-6 Texan II (a turboprop aircraft) about engine failure during flight at different altitudes and the gains from pitching up after the engine failure ...
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### Bell Shaped Lift Distribution Literature [closed]

Context: I am very interested in learning about the bell shaped lift distribution (BLSD) for the purpose of designing a flying wing with this lift distribution. This is the first academic topic I am ...
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### Airfoil Sections orientation on a Swept Wing

The swept wing on a typical airliner consists of multiple airfoil sections. Are these sections oriented perpendicular to the wing leading edge, or parallel to the longitudinal axis of the fuselage? ...
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### Improvements in supercritical airfoil design from 1980 - 2000

I originally asked a question (Comparisons between the A340 and 747-200 wing: sweep angle and span) about the technological developments which allowed the Airbus A340 to have a wing with greater ...
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### Is flow attached in the center of delta wing?

Is flow attached in center of delta wing or only on the edge where two vortices operate? Any video of delta wing vs AoA with smoke?
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### Can big vertical strakes produce "vortex-lift" at high aspect wing?

Delta wings use a strong vortex flow to keep flow attached even at high AoA (30°). My goal is make high aspect wing with highest CL and stall angle, and I don't care about drag. Can we use big angled ...
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### What is the maths behind Loitering of Aircraft?

I am making a controller for loitering using PIDs. The equation which is used to find the radius of circle given bank angle and speed is in following link: How to calculate angular velocity and radius ...
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### Could the Wright Flyer II takeoff without wind?

The Wright Flyer II could reach about 20 mph of airspeed on the track alone. The aircraft needed an airspeed of about 30 mph to make a proper takeoff (without hanging in ground effect). Before the ...
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### What is the modern approach to extract vehicle system responses to control input? [closed]

What is the modern approach to extract vehicle system responses to control input? Is everything thrown into a CFD simulation and the responses recorded or is something else done? Are wind tunnels ...
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### Converting 2d Cl to 3d [closed]

I am trying to convert 2d Cl data obtained from javafoil for a NACA 4412 into 3d data to be used for analysis of the airfoil, but cant find any equations online
1 vote
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### Extrapolating Oswald Efficiency Factor from CL^2 vs CD Graph

I have plotted this CL^2 vs CD graph for a glide test performed in a flight simulator. I want to find the Oswald Efficiency Factor, e from it and I assume I can do that from its gradient. With a wing ...
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### Are the aerodynamic benefits of winglets similar for both powered airplanes and gliders?

Are the aerodynamic benefits of winglets similar for both powered airplanes and (unpowered) gliders? (without considering fuel consumption of course)
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### Is there a difference from alignment with the fuselage between J79 and Spey engine versions used in the F4?

Is there a difference between the J79 and Spey engine versions used in the F4 Phantom in terms of alignment with the fuselage? It looks to me like the Spey nozzles are pointing downward.
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### What is the name of the effect that causes a plane in a dive to go up?

What's the name of the effect that causes the aircraft to automatically pull out of a dive and buffet up due to aerodynamic lift produced at high speeds?
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### How can I derive lift coefficients of wing area and horizontal stabilizers seperately from available data?

I am fairly new to aerodynamics and I am trying to create a flight simulation based on data available for F-4E Phantom. I found various flight test data for this particular aircraft and trying to ...
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### How can I estimate the coefficient of lift for take off?

For the CLto (take off lift coefficient), is there some way to estimate this? I was thinking of using CLmax but wouldn’t this be too big? I was thinking maybe CL cruise?
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### Where should vortex generators be positioned on the chord line?

Where is the best place for vortex generators? Maybe at the place where airflow speed is highest to induce strongest vortices?
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### Can vane delay flow separation? [closed]

In general is a slat better than a vortex generator to delay flow separation, for high AoA or extremely curvature wing/objects? Does this "roof vane spoiler" works same as slat at wing, ...
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### Does static pressure(p - p∞) at wing surface change exponentially, with square of the velocity?

Integration of static pressure over wing we get lift. and Formula for lift is L= 1/2 x Cl x A x V2 x ro; that implies that static pressure (p - p∞) change exponentially(as square of velocity), becuase ...
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### What happens to Lift and Drag on aircraft (and its components) when sideslip is increased gradually from 0 degrees to 90 degrees?

I possess an Aerospace Engineering background, and work as a Aerospace structural analyst at a local firm. A portion of my job is dedicated to determining the critical conditions that the aircraft and ...
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### How would a belt sander wing perform?

This is a theoretical question, the belt sander is an analogy to help visualize. How would a rectangular wing that is able to make its outer skin circulate around the airfoil perimeter perform? ...
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### Effect of Vortex Shedding in lift and drag coefficient?

I want to calculate lift and drag coefficient of a airfoil at multiple using CFD simulation. I am using steady state simulation to run analysis. However I am worried about results. Does steady state ...
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### How can ground speed be higher than airspeed? [duplicate]

I've heard that ground speed is higher than air speed when the plane is being pushed by wind wind. But how is this possible? Wouldn't your AirSpeed also increase since you're going faster?
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### Why airflow travels faster on upper wings?

I have been looking for solutions and come up with two popular explanations: Conservation of mass / Continuity For a positive-cambered wing, the streamlines would be compressed/converged at the ...
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### What is max angle of surface without stall?

AoA is by defintion angle between choord line and airflow, here is 25°. But max effective AoA here is 60°, so flow will separate for sure here.. What is max lets call it "effective AoA" that ...
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### Power calculation of propeller

This is probably a very simple question, but I have been really struggling and need your help. I have simulated a propeller with these parameters on Ansys: Thrust: 2000 N Angular Velocity: 314 rad/s ...
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### Why is this angle of attack sensor tab not symmetrical between the leading and trailing edges?

Here is an Angle of Attack (AoA) sensor I took from here. If you are interested to know the AoA detail, just click the link. You may see what is inside it. But not sure what airplane's AoA sensor it ...
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### What is the AeroVironment Helios' Kármán line?

If it's true that the NASA/AeroVironment Helios maintained level flight 96,000 ft above sea level at a maximum airspeed of 23.5 kts (43.5 km/h) I assume it must have a very high Kármán altitude, the ...
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### How to calculate lateral velocity of a turning aircraft

An aircraft in a 45 degree banked turn has a horizontal lift force vector equal to the weight of the aircraft. Although the Coefficient of Drag is much larger for the aircraft profile, it seems there ...
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### Effect of velocity of air on stagnation pressure

Why does stagnation pressure remain unchanged when velocity of air increases if the formula is: stagnation pressure = static pressure + (1/2×density×velocity$^2$)
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### What is a spool in any jet engine, what is its funtion?

I am a student and I'm trying to determine how a spool works in an engine. What effect does it have depending on the number of spools on the performance of the engine? I tried to find it on Google but ...
1 vote
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### Is a wing lift distribution smooth in the presence of a prop?

Wings designed to minimize induced drag have a smooth distribution of lift from root to tip. Whether elliptical for span constrained wings or more bell shaped to minimize structural weight, ideal ...
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### Why does static directional stability decrease with altitude?

At constant CAS, high altitude means lower air density and therefore higher TAS: this decreases the aerodynamic damping during a rotation. For this reason, I cannot understand why directional ...
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### What is the effect of aspect ratio on cruise velocity?

Does the Aspect ratio affect the Maximum cruise velocity please? I was thinking it wouldn’t as Aspect ratio= b^2/S. If I wanted to go quicker I could just increase my span and decrease S?
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### why normal surface pressure over wedged cone is greater than freestream pressure

I came across this question in "Fundamentals of Aerodynamics" by John Anderson, although I knew how to solve the question, I didn't understand why we had the surface pressure on the wedge 1....
1 vote
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### Is this description of lift and drag coefficients correct?

In my course (Principles of Flight) written: The effect of CLift is not linear. This means that Lift doubles for double the lift coefficient. And The effect of CDrag is linear. This means that for ...
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### Can free fall velocity be used to start a ramjet?

A comment to this question suggested, followed by a smiley, that dropping it [a ramjet engine] from orbit might start it. This got me thinking if this really would be possible. This Skybrary article ...
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### How to calculate the inaccuracy in the "standard" turn radius equation, for supersonic airspeeds

I learned to calculate the radius of a level turn (r) using the function $r = \frac{V^2} {g . tan(bank angle)}$. V is true airspeed, g is the local gravity constant. But now I have seen in the ...
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