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Questions tagged [lift]

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

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How much can 3 fans 7 inches in diameter and each a generating 160 cubic feet per minute airflow rate lift? [duplicate]

I'm working on a hoverboard project and am having trouble finding out the maximum weight these fans could lift.
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5answers
247 views

Do horizontal stabilisers provide any lift?

Do jumbo and smaller airliners' horizontal stabilizers provide any lift? Apart from maintaining the aircraft's angle of attack, can they perform the dual function that includes adding some lift as ...
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1answer
218 views

How fast do four Tire-Propellers have to rotate to lift 2000 lbs? [closed]

I just saw this come out, Goodyear's Tire-Propeller Concept – a combination tire that can also act as propeller (well, more like a ducted fan I guess). There's a neat video that goes with it, ...
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1answer
126 views

What effect does the angle of attack have on lift and drag?

In general, what effect does the angle of attack have on lift and drag? I understand the the B-25 take-off run was normally in excess of 1500 ft, the exact value dependent upon load, density altitude,...
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Was the Space Shuttle aerodynamically neutral while piggybacking, or did the combination act like a giant biplane?

Trying to investigate this question, I see that 'Ask the Captain' says: The weight of the shuttle is calculated like any payload. The 747 produces enough lift to fly and to carry the weight of ...
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1answer
155 views

What disadvantages does flying a drone close under a ceiling have?

If I want a drone (quadcopter) to be flying always under a surface and close to this surface (i.e: under a table 5cm away from the surface), which are the disadvantages this would have in the lift ...
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4answers
238 views

How is vertical speed managed in Airliners? [duplicate]

When an Airplane starts to take off, the Horizontal velocity would generate it the necessary lift, and then Airplane pitches up to further increase the lift. As the Airplane is climbing up, the net ...
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2answers
107 views

How does wing aspect ratio influence lift and drag?

I know simmilar questions are all over the internet (and this website too), but there's one thing that i just cannot comprehend and none of the articles i read could explain it properly. According to ...
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0answers
29 views

Determine “basic lift distribution” over a wing that has a circulation distribution

I don't understand what they mean with basic lift distribution. I have calculated C_L which is 5a (a is alpha in radians). I added the relevant equations here.
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1answer
57 views

How do we derive Lift Coefficient of an airplane's wing?

In many references I read that lift coefficient ($C_l$) is a product of wind tunnel test. But many times I read the formula to calculate the coefficient of lift. From the lift equation, $$L=\frac{1}{2}...
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1answer
239 views

What was the lift equation used by the Wright brothers?

NOTICE: The modern lift equation and the lift equation used by the Wright brothers in 1900 are slightly different. The lift coefficient of the modern equation is referenced to the dynamic pressure ...
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5answers
277 views

How to recognize the horizontal winglet in the Horten design, or the experimental glider in this video?

Comments below the NASA Armstrong Flight Research Center video Proving Prandtl- With A Twist! incclude: This video is entirely a hidden jewel in youtube, it deserves much more attention than ...
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4answers
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What would be a simple aerodynamics simulation software for a student? [closed]

I have a project due 2 weeks from now that demands we make a glider using Styrofoam. I'd like to simulate the results as I plan my glider before I build it. Which simple software, which allows ...
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2answers
416 views

What prevents BFS from becoming unstable when pitching from horizontal to vertical?

In this video from (SpaceX's BFS landing) there is a point where the ship tilts from horizontal « belly first » terminal velocity freefall, to vertical « engine first » landing position. The graph ...
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3answers
247 views

Why hasn't anyone tried making two propellers facing upwards and the other two facing downwards? [closed]

Within a quadcopter, I know usually it's all the propellers facing upwards or all of them facing downwards. Why hasn't anyone tried making two propellers facing upwards and the other two facing ...
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2answers
135 views

Does Lift generation create a vacuum over an aerofoil? [duplicate]

According to Bernoulli’s principle, Airflow speeds up over an aerofoil which decreases the pressure. and I read somewhere that when airflow speeds up over an aerofoil, this creates a vacuum. how true/...
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0answers
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Does the Lilium VTOL wings produces lift during takeoff?

I just had a look on some of the recent development in the personal VTOL electrical aircrafts. I am wondering if the Lilium VTOL wings produces lift during takeoff? I would expect a quit high wind ...
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97 views

Calculating induced drag approximation using XFoil generated parasitic drag

I am trying to do rough predictions of induced drag using the XFoil results for parasitic drag. To do so, I am using the lifting line equation for induced drag and the Oswald efficiency number: $C_D=...
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1answer
74 views

Calculate g's per radian

I'm currently attempting to assign handling qualities to the A-4D, and I would like to know how to find the term: $ n / \alpha = \overline{q} \times C_{L\alpha} / (W / S) $ where $C_{L\alpha}$ is ...
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5answers
287 views

Descending on a given glide slope (e.g. ILS) at a given airspeed— is the size of the lift vector different in headwind versus tailwind? [duplicate]

We had a discussion with friend and we were talking about if the airplane is on approach and the one is landing with tailwind and the other one is landing with headwind, so both have the same value of ...
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1answer
89 views

Why do I see moisture coming from the middle of the wing as well as wingtip vortices? [duplicate]

A lot of times I see small tube like streams of visible moisture training from the middle of an airliners wing. I assume this is induced drag created by wingtip vortices, when the aircraft is heavy, ...
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0answers
66 views

How much lift can be generated by the intake lip of a duct?

How to calculate the extra lift gained by the intake lip of a duct? Aside from improving efficiency by preventing tip vortices, if a duct has a bell-shaped intake, this lip around the edge creates ...
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4answers
159 views

How fuselage creates lifting force when plane flying on a side?

On a question "How plane able to fly on a side" people answer that it's because fuselage shape crate lifting force and plane should have enough thrust. But that seems vague to me. How fuselage creates ...
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1answer
336 views

Why is an elliptical wing planform so aerodynamically efficient in layman's terms?

Below is part of an answer to the post 'For the elliptical wing, what is elliptical, and why is drag regularly distributed?': On the untwisted elliptical wing the local lift coefficient is constant ...
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5answers
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Why does a stall decrease lift, rather than increasing it?

A stall occurs when the angle of attack of a wing or other airfoil becomes so high that the airflow over the upper surface of the wing separates from the wing, rather than remaining attached to it; ...
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1answer
95 views

Lift and Drag Coefficients using load cell data

I have a MAV and I need to find out the lift and drag coefficients for the wing and tail. I am not available with a wind tunnel so I will be using a load cell along with a separate wind source. Now I ...
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2answers
74 views

How do rotorcraft achieve lift?

How do rotorcraft (helicopters, and other rotary aircraft etc.) achieve lift? I mean, obviously the rotor. But who knows the specifics? What are the physical, mechanical requirements of a rotary ...
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6answers
3k views

Is lift in fact a kind of drag?

Given the similarities between Lift and drag and their very similar relationships to the density, surface area, and airflow velocity, could one, in theory, describe aerodynamic lift as a kind of drag ...
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3answers
132 views

Does Buoyant Lift Force scale with Load Factor?

Let's say I am flying an airplane that has a weight of 100,000 kg with a 1G load factor at normal steady flight. I have helium lift assist that is providing 50,000 kg (50%) worth of buoyant lift force ...
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0answers
698 views

How do you calculate the lift coefficient of an airfoil at zero angle of attack?

Thin airfoil theory gives $C = C_o + 2\pi\alpha$, where $C_o$ is the lift coefficient at $\alpha = 0$. However, I couldn't find any equation to calculate what $C_o$ is which must be some function of ...
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2answers
263 views

Are high lift wings bad for faster speeds

I notice a trend in many aircraft designs. If the aircraft was designed to go slowly but have shorter takeoffs/landings they use airfoils with a high lift. However for long endurance flights they use ...
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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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1answer
115 views

Why changes the lift during turning with sidewinds? Why is there relative wind in the wind-frame?

I started doing some simulations with XPlane and could observe a very interesting effect when doing turns in the presence of constant wind: All simulations are done with the XPlane Cessna 172 (?) ...
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1answer
136 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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4answers
3k views

What is the aerodynamic motivation behind vortex generators?

An airplane's wing creates lift efficiently when the airflow is parallel to the chord of the wing. Vortex generators twist the airstream on the wing surface. Doesn't this kind of twisted airflow ...
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0answers
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If elliptical lift distribution is considered in every case, does the induced velocity change based on the shape of the wing?

Shapes like rectangular, curved, trapezoidal etc. Here I mean rectangular or curved when viewed from the top. The sectional airfoil shape is the same in each case.
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1answer
273 views

How does the Coanda effect help some aircraft produce more lift?

How exactly does the Coanda effect affect the air stream on the wing of, e.g., an AN-72? The Coanda effect makes an air stream flow on the curved (outboard) surface object which it has produced from ...
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2answers
2k views

Do negative angles-of-attack create lift?

(wikimedia.org) A typical curve showing section lift coefficient versus angle of attack for a cambered airfoil. Based on the graph above, do negative angle-of-attack values create lift? How?
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3answers
478 views

What is the “Centre of Pressure”?

This question may sound naive but surprisingly it puzzles me. A wing has a centre of pressure, does it mean that lift acts on point and not on the whole chord of an airfoil?
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2answers
186 views

How to adjoin wing skin to wing ribs?

I saw a youtube video (from a channel called Real life guys) where gum was used to join the ribs of their homemade plane to the skin and I saw another video where the wing skin(tedlar) was literally ...
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1answer
212 views

why lift is greater at wing root [duplicate]

Is lift greater at the wing root of an horizontal wing,just like it's greater on a tapered wing?
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5answers
7k views

Why are wings load tested upside down?

Why are wings load tested by putting weights on the underside of the wing (placed upside down)? A wing is being pulled into the air from its upper surface in flight, so shouldn't it be load tested in ...
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0answers
133 views

When rearranging the lift force equation to solve for lift coefficient instead of lift force, why is the numerator often given as F not 2F?

the standard description of the Lift force affecting the lift surface is: $$ F={\dfrac{1}{2}}\rho v^{2} SC_{L} $$ the basic rearrangement gives the following definition of the lift coefficient: $$ C_{...
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2answers
239 views

Are high-frequency flapping wings efficient and scalable at high Reynolds numbers?

Is high-frequency flapping (similar to how dragonflies fly) an efficient lift production method at high Reynolds numbers? I have not seen anyone develop wing suits with high frequency flapping, is ...
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1answer
232 views

Do wingtip vortices cause a decrease in the lift component of aerodynamic force, and do planes need to pull more AoA to compensate?

So, from what I know about wingtip vortices, they shift the angle of the relative airflow to where the effective angle of attack of the airfoil is lowered. Since the aerodynamic force is always ...
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3answers
227 views

If we use upper surface blowing and externally blown flap on the same wing will lift correspondingly be very high?

With two engines, one above and one below the wing, will the lift be the sum of two lift increments (produced by upper surface blowing and external blowing)? I am trying to make a jet suit and I am ...
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1answer
465 views

Is pressure lower than ambient on the pressure (bottom) side of an airfoil? [duplicate]

I've been reading about this for quite some time and thought I understood it. Then somewhere someone mentions that air under the wing has higher velocity than ambient thus a lower pressure than ...
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3answers
149 views

How is the centre of lift estimated for airplane models before they are being mounted in a wind tunnel?

They mount the airplane models or parts of an airplane like just a wing, or a rudder in wind tunnels to test their drag and lift, stability, etc. How do they know where to hang it from or mount it on....
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2answers
186 views

Does wing sweep affect the direction of lift?

Given both a straight and swept wing (identical otherwise), exposed to the same airflow, would the direction of lift be the same? Please see below a crudely drawn example of my thinking. Additionally,...
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2answers
3k views

How exactly can an airship lose lift?

On this wiki page (under 'Comparison with heavier-than-air aircraft'), the altitude record of the L-55 Airship states: The ultimate altitude record for a rigid airship was set in 1917 by the L-55 ...