Questions tagged [lift]

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

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34 views

Is there any bibliography for triplane aircraft design?

I've been tasked with designing an RC aircraft that has the greatest lift force for a specified wingspan, total length and takeoff velocity, and thus have been studying the different wing ...
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Does downwash increase or reduce lift generation?

I’m wondering about the impact of downwash on lift generation. I've read that, because downwash creates lift according to Newton's third law of motion, increases in downwash due to greater AoA (...
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What is the effect of wing flex on wing's airfoil shape and its performance effect on wing?

There are good amount of discussion on wing flex in this forum. I am more interested in understanding the effect of flex on aerofoil shape of the wing and its impact on flight performance. Do ...
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Why don't smaller powered airplanes have better lift-to-drag ratios?

Many airliners have LDRs near 20, and it sounds like the electric Eviation Alice may have an LDR of 24 at 240 kts, but many small planes typically have LDRs of only 8-10. It seems like they could ...
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4answers
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Aerodynamics of Flight Control Surfaces

From what it appears to me, flight control surfaces seem to be taken for granted. In terms of how they actually work and what kind of physical outputs they give in terms of forces and such. Take for ...
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1answer
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Derivation of the Takeoff equation

I am trying to understand the derivation of some simple equations to calculate the neccecary takeoff speed for an airplane (under ideal conditions). Which is taken from 15. Takeoff and Landing. My ...
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1answer
86 views

What is the definition of Lift?

Lift is a term that is used very frequently here, but I cannot find any post explaining what it is exactly. I am looking for the exact definition of lift, not an explanation of how it is generated. ...
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6answers
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Can a wing generate lift in excess of its aircraft's weight?

"For a plane or bird to fly, its wings must produce enough lift to equal its weight. " I got that excerpt from "https://www.sciencelearn.org.nz/resources/300-wings-and-lift". My questions: (1) Can ...
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1answer
114 views

How is d(Cl)/d(alpha)@stall and Cl increment to stall defined in Xrotor?

I hope there are some people around here with some experience in Xrotor than me. (Xrotor is:"XROTOR is an interactive program for the design and analysis of ducted and free-tip propellers and ...
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1answer
107 views

What is suction peak?

Can anybody explain to me what suction peak is and does it have anything to do with lift and drag? I've read that suction peak is the point where the coefficient of pressure is the least and is ...
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How can Lift = Weight; if airliners fly with Thrust-to-Weight ratios = 0.3? [duplicate]

Question: I'd appreciate it a lot if anyone could explain how the wings can generate lift that is 3.3x more than engine thrust? Is there any experimental proof that this? Or is the assumption that ...
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1answer
135 views

Was the Coanda effect known in 1868 to Matthew Piers Watt Boulton (the one who described the first ailerons)?

Matthew Piers Watt Boulton is known as the inventor whose 1868 British patent No. 392 nullified any claim of the Wright brothers that they discovered the ailerons (see FIG. 5-7). It seems now that ...
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1answer
32 views

How do I factor sweep and dihedral in the lift equation?

I'm guessing that you add cos(angle of dihedral) to calculate lift loss by dihedral, but I'm not sure how to factor in the lift loss by the wing swept. Could someone help me include lift loss due to ...
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Calculating Lift of a closed-wing drone

A group of students and I are designing a theoretical closed-wing drone and need to calculate lift based on the NASA lift equation. We've designed fixed-wing aircraft before and when it came to ...
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4answers
223 views

How much of an airplane's forward energy is lost to lift?

An airplane needs to move forward to generate lift, and because energy isn't created from nothing, all the kinetic energy of lift comes in the form of drag, where air (air resistance) turns forward ...
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What is the purpose of the propeller?

The propeller generates thrust, but what is the purpose of thrust of propeller? Is it to help the aircraft move forward or to produce lift to rise up?
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What is difference between pitch & lift? [closed]

What is the difference between pitch and lift of an aircraft?Please kindly try to include graphics with your answers
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Is there a V speed for the point an aircraft starts an ascent at 0 angle of attack?

Some aircraft with an angle of incidence or cambered airfoils are capable of climb without any angle of attack, Is there a V speed for the speed at which an aircraft starts a positive climb?
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In the Cl vs Cd graph, Why the drag coefficient decreases initially with the small increment in lift coefficient?

Cd = Cdo + KCl2 Total drag = Parasite drag + Induced drag When Cl = 0 , Cd = Cdo Increasing in Cl introduces another component of drag (Induced Drag) and therefore the total drag Cd should be ...
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100 views

Downwash distribution on basis of Lift distribution

I am new here so I might make some elementary mistakes. Correct me if I am wrong. I just stumbled upon the downwash distribution for a given lift per unit span distribution along the wingspan. I have ...
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1answer
266 views

What are the relative contributions of the body and wings to missile lift?

Slender bodies like arrow shafts, airliner fuselages, and submarine hulls are all capable of generating lift, albeit much less efficiently than a high aspect ratio wing. They also generate little drag,...
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166 views

How do I calculate the center of lift?

See my other question here for the background context. Consider this simple plane. I have applied the 4 basic forces: lift, drag, weight, and thrust. My question is, where, precisely, do I apply the ...
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1answer
130 views

Why is ground effect greater over smooth hard surfaces?

Helicopter Flying Handbook: Ground effect is the increased efficiency of the rotor system caused by interference of the airflow when near the ground. The air pressure or density is increased, ...
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1answer
133 views

What is an example of a quantitative analysis for the lift using Newtonian mechanics?

There are several different ways of explaining how an airplane generates lift. The simpler qualitative explanation uses Newtonian mechanics (the third law is invoked to explain how the wing pushes air ...
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4answers
2k views

How does speed affect lift?

I understand the lift coefficient shown above. But does lift increase with speed, and how? I understand I can't apply this to the graph as it is a coefficient, but if I had an angle of attack of 10 ...
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2answers
102 views

Can the back tail of an airplane move the neutral point backwards?

I'm currently in the process of designing a prototype aircraft and since I don't have very much experience with this I have the following question: I know that the center of gravity of an airplane ...
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1answer
128 views

Is lift generated only by wings? [duplicate]

In modern aircraft is lift only generated by wings or can other parts of fuselage generate a significant amount as well, to the point it needs to be accounted for when designing a plane?
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What are the effects of endplate on airfoil section?

A 3D wing cannot achieve the same high lift/drag ratio (more than a hundred sometimes) displayed by a 2D profile (airfoil section). This is due to 3D effects like spanwise flow, wingtip losses(...
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Why do Wingtip Vortices affect the upwash ahead of the aerofoil?

I understand that wingtip vortices increase the downwash aft of the aerofoil and the theory that they will alter the effective airflow angle, reducing effective angle-of-attack, with the total ...
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1answer
180 views

How beneficial are flaps when landing with a tailwind?

I understand that flaps are devices used to increase the amount of lift and drag. When landing with a tailwind your groundspeed will be higher. Therefore, flaps would help reduce this groundspeed, ...
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3k views

How can lift be less than thrust that is less than weight? [duplicate]

Physics in schools teaches two contradictory and mutually exclusive things: That the upward lift force on an airplane in flight equal its weight (Lift = Weight = Mass x Gravity). This is based on ...
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2answers
411 views

How much lift does the wing attach fitting actually carry?

How do I calculate the lift force that the the bolt that join the wings to the fuselage of a strutted or braced airplane carry? I know in a cantilever airplane,the bolts have to carry all of the lift ...
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1answer
39 views

How could I find the air velocity and lift force?

As shown below I have this information as shown below in the picture. I got the density according to the ISA standard 𝜌 = 1.225[kg/m^3] and 𝐶𝐿 = 𝐶𝐿𝛼 (𝛼−𝛼0) is calculated as below : α=−4: CL=...
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How could I find 𝐶𝐿𝛼 lift coefficient slope?

I'm trying to find 𝐶𝐿𝛼 lift coefficient slope through the below diagram, could anyone explain for me please, how could I find it? by the way, I depend on this equation 𝐶𝐿 = 𝐶𝐿𝛼 (𝛼−𝛼0)
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3answers
1k views

Is there a simple relationship between angle of attack and lift coefficient?

Is there an equation relating AoA to lift coefficient? I have been searching for a while: there are plenty of discussions about the relation between AoA and Lift, but few of them give an equation ...
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2answers
188 views

Will creating a strong back pressure within a ducted propeller enable an aircraft to attain a higher altitude?

I would like to know if creating a strong back pressure within a propeller duct will enable an aircraft to attain a higher altitude. Please reference the conceptual drawing below. This is showing a ...
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113 views

Trying to find the vertical acceleration by subtracting weight from lift

I'm trying to determine the vertical acceleration component of a plane with the following specifications: Density of air: 1.29kg/m3 Speed: 33 m/s Wing area: 13.97 m2 Lift Coefficient: 1.5 Mass:560 kg ...
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1answer
202 views

How do changes in flight affect L/D max and the speed at which I must travel to maintain it?

I have an plane flying at L/D max and I want to maintain L/D max. Firstly, if this plane burns through a portion of fuel and becomes lighter, how would I have to change the speed to maintain it? My ...
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What is the relation between solidity and lift coefficients?

I've seen this graph in a couple of places. I'm not sure what it's supposed to mean, as the formulae I've seen in the papers cannot be found in any standard book or reference. Please let me know if ...
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452 views

Why isn't the bell distribution used?

Why has the bell distribution not become widely used? Is the bell distribution only ideal in inviscid flow scenarios or is there another reason for the lack of use?
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How do conventional missiles fly?

With the exception of cruise missiles, most missiles don't have any obvious lifting device. If you watch a missile being fired, prior to its rocket firing it does exactly what you'd expect: ...
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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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481 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
398 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
339 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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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
427 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
615 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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1answer
315 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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