Questions tagged [lift]

The force acting on an aircraft in opposition to gravity which keeps the aircraft in the air.

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Calculating lift on airfoil by integrating pressure [closed]

Currently, I am doing a project in high school. I am 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 ...
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What methods are used to calculate the geometry needed to obtain a bell-shaped lift distribution?

In aerodynamics, what methods do people use to calculate the geometry of a wing (and body) needed to obtain a bell shaped lift distribution? Please go into as much detail as possible for a stack ...
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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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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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Why does lift coefficient not change with velocity in inviscid flow?

Why exactly is lift coefficient constant with velocity in inviscid flow? (For a given angle of attack, 2D section and fluid, pre-stall etc) Does it come out in the derivation of lift coefficient or ...
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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 ...
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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
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Which one produces more lift?

I have come across this question on Twitter. I have found a similar question here. The aircraft isn't flying but just doing Cobra Maneuver. Since the direction of the lift is in the same direction and ...
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Never heard of this Aerofoil?

I just came across this aerofoil, 65-2xx? I searched this but it doesn’t come up with anything like 65-200 for example but instead SG6051 which is the closest I could find to this? Am I missing ...
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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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How do I calculate where a wing is most likely to break?

I want to make a delta wing out of carbon fiber, but I do not know how many carbon fiber layers would be needed to prevent the wing from breaking due to shear stress. What would be the calculations ...
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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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The stall velocity condition: Exactly what is stall velocity? [closed]

Question: if my stall velocity is 20m/s, then... If the airplane is travelling at a velocity greater than or equal to the stall velocity, can one assume the plane will not stall? Can one assume that ...
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Can induced drag be negative?

For an aircraft in straight and level flight, lift-induced drag is the horizontal component of the force perpendicular to the wing chord. Positively cambered aerofoils generate lift starting at small ...
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Why does lift decrease and drag increase when approaching the stall condition?

This is an ECQB-PPL question specifically asking what happens before the stall. I do understand that after the critical angle has been reached, the airfoil is no longer generating lift (so obviously ...
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Are horizontal engine pylons generally shaped to provide lift (in either direction)?

Most civil multiengine jets and some civil multiengine propeller aircraft have engines mounted in nacelles on the ends of pylons extending some distance away from the wing or fuselage. Wing-mounted ...
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Is it possible for the lift force unit vector to be equal to the weight force unit vector?

I know that the drag force is parallel to the direction of flow, thus equal to the unit vector of velocity. But if you consider a vehicle, when its angle of attack is below the velocity vector from a ...
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Help with calculate forces from pressure distribution

V=50m/s deltaPg= -981 Pa deltaPd=490,5 Pa c=1m r.com/PCshZ.png Above is calculate Fz with integrals and with average pressure. Why F3 is calculate from 0 to C/2 if pressure distribution is drawn at ...
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How to solve normal and axial aerodynamic force coefficients integral equation to calculate lift coefficient for an airfoil?

$$ c_n = \frac{1}{c} \left[ \int_0^c (C_{p,l} - C_{p,u}) \, dx + \int_0^c \left(c_{f, u} \frac{dy_u}{dx} + c_{f,l} \frac{dy_l}{dx} \right) dx \right] $$ $$ c_a = \frac{1}{c} \left[ \int_0^c \left(C_{p,...
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How to calculate the takeoff speed for a hypothetical aircraft?

Given some basic information such as: aircraft weight wing load (including wingspan, and basically the whole wing configuration) airfoil profile coefficient of lift angle of attack Is it possible to ...
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How to turn inviscid data to viscous?

I have used Panel method to calculate Cp vs x/c graph and CL. But as panel method assumes attached flow it does not give an flow separation and thus in CL vs alpha graph I could not find any stall. My ...
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Why is the CG assumed to be between the CP and the tail?

While discussing stability (Longitudinal, Lateral, Directional), invariably, all texts assume CG to be between CP and tail. Ex: Look at the specific image in wikipedia https://en.wikipedia.org/wiki/...
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Will air accelerate over a wing and generate lift, if the air has zero viscosity? [duplicate]

Will air accelerate over a wing, if the air has zero viscosity? Will the wing produce any lift under these conditions?
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Streamline Curvature Theorem applied to Airfoils?

I am new to studying aerodynamics and taking up aeromodelling and am currently learning how lift is obtained in-depth. When studying the two common explanations as to how lift is generated by an ...
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How does a forward lifting surface affect ideal lift distribution of a main wing?

In Peter K's answer to this elliptical wing with lowest drag question the minimum induced drag lift distribution for a wing is described as one with a constant downwash angle across its span. When a ...
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How do thick and thin airfoils compare in lift generation?

I find myself confused when comparing the lift generation amongst Thick and Thin Airfoils. A paper to which I have added reference below claims that thin airfoils are better in generating lift because ...
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Why does NASA say $v^2$ is velocity squared rather than speed squared?

Lift and drag forces scale as the square of the relative flow speed, $v$. But speed is the magnitude of the velocity vector; that is, speed is the square root of the sum of the squared velocity ...
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How do I calculate induced drag? [closed]

How would I go about solving this problem? An aircraft has 6000lbs of total lift and a downwash angle of 6 degrees. Remember that the total lift vector is tilted aft by HALF the downwash angle. What ...
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Are the lift / drag coefficients considered dimensionless?

Since the lift coefficient, $C_L$, and the drag coefficient, $C_D$, are obtained by rescaling the full lift and drag by $$\frac12 \rho A v^2$$ does that mean they're dimensionless numbers? It's ...
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How much could you increase lift using ailerons alone?

If a plane had ailerons that could be moved in the same direction, could the lift be increased by a non-negligible amount?
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What is the relationship between aspect ratio and lift-dependent drag? [duplicate]

It has been a long held view that aspect ratio of the wing has a significant role to play in the lift-dependent drag. However, mixed opinions have been expressed on the importance of aspect ratio in ...
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Is there a limit to how large an airplane wing can be? [duplicate]

There are some agreeably large planes out there, like the C-5 Super Galaxy. But how big can these planes' wings really get? The heavier the plane, it is usually larger, and with size of the fuselage ...
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Center of Gravity and Center of Lift stability

I have recently been reading about the center of gravity and center of lift. On the German Wikipedia there are many different graphics about the relation between the center of gravity and the center ...
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Would a flying-wing drone fly farther if filled with helium?

I'm wanting to build a flying wing designed drone and I'm wondering if I were to fill the fuselage with helium if it would improve it's range.
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In which part of the flight does a plane reach maximum lift?

In which part of the flight does a plane reach maximum lift? My logic: I think a plane reach maximum lift in a horizontal flight, when a plane start rolling on a runway, landing gear produce more ...
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Is it better to reduce drag or increase lift?

Essentially my question is, in general is it better to have a lower drag or a larger lift. I know lift to drag ratios are used as an indicator but I think these don't give the best picture. For ...
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What are the best methods for calculating lift during different stages of flight?

Supposing I have the all dimensions of an RC airplane: wingspan, NACA airfoil, aspect ratio, fuselage length, etc., what would be the best methods of calculating the expected lift the aircraft should ...
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Center of Pressure(CP) [duplicate]

The center of pressure is: A)The point at which the Total Aerodynamic Force acts B)The point where the lift force acts C)The point where the resistance force acts Only one answer is correct,i think ...
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Difference in lift generation for a swept wing and straight wing in subsonic condition

Would there be any differences in lift for a straight wing and swept wing (front or back) with the same airfoil cross section, same chord length, same wing span, and same area when flying in subsonic ...
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Explained intuitively, why does aspect ratio affect induced drag?

Over the last few hours, I've been trying to intuitively understand induced drag, and how aspect ratio affects it. I already know the equations, but while they explain the relationship, they do not ...
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If an elliptically-shaped aerofoil gives the optimum lift distribution, why aren't propeller blades designed around this ideal?

So given an elliptical lift distribution is the most efficient, why are propellers not designed around this? Props aren't affected by the adverse stall characteristics that concern a "main", ...
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4 answers
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Can lift occur if air is flowing over an object, but not under it?

Can lift occur if air is flowing over a fixed-shape object, but no air is flowing under any part of the object? Maybe the object is the top half of a wing that's glued to the ground, or the object is ...
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How does the airflow above an airfoil account for the downward turning-action of the airflow below the airfoil?

Wikipedia provides an explanation of the lift force in terms of flow deflection and Newton's laws, emphasis mine: An airfoil generates lift by exerting a downward force on the air as it flows past. ...
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Lift Pressure Distribution [closed]

If the pressure goes always from high to low, we should have a compression, due the lower pressure of the air stream over the upper surface, and an expansion in the airstream in the lower surface. So ...
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Is it possible to stall a stationary helicopter through excessive collective input?

I understand that helicopters can suffer from "retreating blade stall" where the retreating side of the rotor has low airspeed and stalls in a typical way that airplane wings stall. This ...
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How dangerous are tailwind gusts for STOL aircraft?

If I fly close to stall speed with a STOL plane and gust of 20kts tailwind comes at me,it will cause sudden reduction in lift ,becuase plane has inertia so it can not accelerate instantly. How ...
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increasing lift in a plane by placing engine in such a way that the air coming out of it washes over the wings to create more lift [duplicate]

I was wondering if the engines of a plane can be placed in such a way so that the air coming out of the engines goes from over the wings so that the velocity of air over the wing is higher and more ...
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Why aren't grid fins used as wings for low speed aircraft?

Grid fins are used "commonly" in aerospace - usually for things like control of guided bombs or spacecraft. The most obvious example is SpaceX's use on the Falcon 9, but the US and Russian ...
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How can the lift induced drag for a wing be calculated?

I have found a lot of information to calculate drag coefficients and I know that total drag can be calculated by $$ D = \frac{1}{2} \rho u^2 S C_d $$ However I was wondering, if I substitute the zero ...
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Why generation of lift is more at mid span of the wing?

For the same condition like same density, wing area, free-stream velocity, From the above figure one can see more pressure differential and hence more lift at mid span of the wing? What causes this ...
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