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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Calclulating lift on airfoil by integrating pressure

Hi, im currently doing a project in highschool, and im looking at the formula in the picture for calculating the lift on an aerofoil by integrating the sum of pressure from the pressure tabs times the ...
0 votes
2 answers
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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 ...
1 vote
2 answers
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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?
6 votes
5 answers
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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 ...
0 votes
1 answer
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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 ...
1 vote
2 answers
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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 ...
3 votes
1 answer
314 views

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 ...
-1 votes
2 answers
254 views

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 ...
6 votes
2 answers
833 views

How does an aircraft's weight affect the V-n diagram?

I have a reasonable understanding of what a V-n diagram shows and what the envelope and the boundaries mean. However, the question I have is how does the weight of the aircraft specifically affect the ...
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1 answer
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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 ...
15 votes
2 answers
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Is airflow ever laminar in the boundary layer, near the wing leading edge?

I often see images of the boundary layer over a wing indicating the airflow is laminar over the first portion of the wing: Transition from laminar to turbulent flow over the wing. Left: source, right:...
6 votes
8 answers
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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 ...
1 vote
1 answer
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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
2 answers
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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
2 answers
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For subsonic aircraft, would adopting a higher wing loading decrease drag?

First, let's assume that problems with approach/TO speeds can be fixed by high-lift devices. Here we read that the wings create more drag than the fuselage. So, an improvement seems obvious; shrink ...
1 vote
0 answers
69 views

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 ...
9 votes
5 answers
638 views

Why does elevator input move the turn coordinator ball in steep turns?

When practicing steep turns, I'm running into an unusual phenomenon. If the airplane is losing altitude in coordinated flight and I apply aft stick pressure to pitch up and correct, I notice that the ...
3 votes
2 answers
311 views

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 ...
6 votes
5 answers
796 views

Why do Leading Edge Flaps (LEFs) create lift while down at slow speeds, but decrease lift while down at higher speeds?

When taking off or landing, both LEFs and trailing edge flaps (TEFs) for fighter aircraft are in the down position to provide more lift. However, when flying around at higher speeds (let's say 500-600 ...
12 votes
2 answers
994 views

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 ...
0 votes
0 answers
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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 ...
2 votes
1 answer
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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? ...
1 vote
2 answers
83 views

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 ...
2 votes
3 answers
1k views

Aerodynamics moment of a wing

An old flight book that I am reading discusses the aerodynamic moment about a wing and talks about an upper and lower lifts. I can see how the pressure distribution on the top surface produces an ...
1 vote
0 answers
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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 ...
8 votes
1 answer
177 views

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 ...
0 votes
1 answer
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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 ...
4 votes
1 answer
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Would it be possible to build a "rocket" using a series of ducted fans?

I'm wondering if it would be possible to build ducted fan "rocket". My idea is to construct the duct from 18650 batteries, and to have a series of contra rotating fans along its length. I can 3d ...
2 votes
1 answer
370 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 ...
1 vote
1 answer
127 views

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, ...
1 vote
3 answers
248 views

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 ...
2 votes
1 answer
133 views

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 ...
2 votes
3 answers
189 views

Projected Area & AoA - Projected area of the wing is variable (as projected on to a surface that is perpendicular to the relative wind)

Does Wing Area vary with angle ot attack? Edit: why we don't recognize that the projected area of the wing as variable (as projected on to a surface that is perpendicular to the relative wind) Per the ...
2 votes
1 answer
171 views

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
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3 answers
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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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1 answer
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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 ...
2 votes
1 answer
2k views

The relation between Euler-angle rate and body-axis rates?

A paper about quadcopter dynamics and control shows the relation between Euler-angle rate and body-axis rates as: Q1: why are there $R_{v2}^{b}(\dot{\phi})$, $R_{v1}^{v2}(\dot{\theta})$, and $R_{v}^{...
5 votes
2 answers
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Do wall-to-wall airfoils produce induced drag?

The walls in a wind tunnel stop air leakage around the outboard sections of an airfoil, and the pressure distribution at the center section is the same as at the outboard sections (if we neglect ...
2 votes
0 answers
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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.
0 votes
1 answer
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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 ...
7 votes
6 answers
2k views

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?
1 vote
1 answer
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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?
1 vote
2 answers
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How are panel codes like xfoil able to model turbulence and predict drag?

Since Xfoil is using potential flow theory, how is it able to predict boundary layer and separation? If I'm adding perturbation terms aren't those still made with fundamental flows?
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1 answer
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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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1 answer
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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 ...
23 votes
1 answer
3k views

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? ...
5 votes
1 answer
278 views

Why don't competition gliders use riblet skin surface to reduce drag?

Price is not a problem in competition gliders, also no problem with in maintenance surfaces like at airliners. It is very easy to wash glider before every race. A riblet surface is proven (PDF) to ...
4 votes
3 answers
280 views

How do you maximize lift while keeping span as short as possible?

This weekend I saw the Fly Baby at the Smithsonian Air & Space Museum at the Washington Dulles Airport, and it was at some point the smallest airplane (since surpassed by the Bumble Bee II, if I ...
1 vote
1 answer
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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 ...
-1 votes
2 answers
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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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