Questions tagged [lift]

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

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2answers
93 views

Does the center of lift have to be in line with the center of mass?

Imagine 2 theoretical planes, A and B, shown in the image below. The center of mass is yellow, and the center of lift is blue. Would plane A and plane B work as well as an airplane with the center of ...
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1answer
65 views

Is there any plane that has wing of both aerodynamic and geometric twist?

For the proper lift distribution, afaik either of the twist are used? Is there any significant difference having one over another and both? Thank you. The above question has one line answer and both ...
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Would this quadrilateral-shaped airfoil produce lift with a zero angle of attack?

I have been recently studying the shapes and characteristics of different high-lift airfoils that have been used for VTOL aircrafts. While studying these different designs today, a particular ...
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2answers
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How to distinguish the induced drag of a lift-producing wing from its pressure drag?

Quote John Anderson Fundamentals of Aerodynamics: "The three-dimensional flow simply alters the pressure distribution on the finite wingin such a fashion that a net pressure imbalance exists in the ...
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5answers
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Could propeller wash provide sufficient lift to take off - even in theory?

I know this seems a crazy thing to ask but it is not the same as lifting oneself by the bootstraps. If you try to lift yourself that way, there are two equal and opposite forces, yet there are ...
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2answers
221 views

What is the reason why dihedrals are used when building a plane? [duplicate]

How does dihedral affect flight characteristics of a plane? I know it increases stability, however is it the only reason why it is implemented? If so, aren’t there more effective methods to stabilize ...
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2answers
197 views

Will this specially shaped can produce any lift?

I am wondering if a specially shaped can will produce any lift as it moves through the air. Please reference the drawing below: This drawing is showing a hollow can that has been cut so that it will ...
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1answer
85 views

When using the Source Panel method and dealing only with sources and sinks, why do lift and drag equal zero?

I am trying to deal with the airfoil with the "Source Panel method", and when I try to calculate the lift and drag, they always equal to zero. And I have found an explanation in some ...
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108 views

How calculated the drag coefficient lift coefficient with pressure coefficient?

I have got the Cp Plot on a wing, now I am trying to calculate Cl and Cd. And the angle of attack is 0 degrees, the wing has been split into N Panels, and the normal vector ni for every Panel is ...
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1answer
69 views

At any given weight or altitude, an aircraft will always lift-off at the same? [closed]

A: Calibrated Air Speed (CAS) B: True Air Speed (TAS) C: Ground Speed D: Equivalent Air Speed (EAS) I think the answer is CAS, but I also think it could be TAS but, isn't TAS calculated after ...
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3answers
230 views

Why is air accelerating over the wing surface?

I know that there are dozens of questions about lift generation here but after reading them I still don't understand everything. My question is: why does air accelerate over the (upper side) wing? I ...
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1answer
246 views

What happens in an F-16 once the aircraft exeeds its service ceiling?

What exactly is the sequence of events that would unfold as an F-16 attempts to exceed its service ceiling? The scenario is simply full afterburner and attempting to simply climb higher and higher (at ...
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The lift and moment of the tail equations

We have The lift of the tail, $$ L_t = C_L.q.S_t $$ The moment of the tail around c.g. $$ M_(cg,t) = C_M.q.S.c $$ look at the S in the two equations. Why the lift of the tail is proportional to the ...
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1answer
102 views

How does vorticity change the lift coefficient of an airfoil?

For airfoils in unsteady motion, the lift coefficient oscillates and the wake is characterized by vortex shedding. How does vortex shedding affect the lift coefficient for an airfoil?
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How can we find maximum lift coefficient of Airfoil?

I am trying to find the maximum Lift coefficient for airfoil NACA 64A-404. I chose this airfoil for wing. I am stuck at finding the Clmax. I tried to use javafoil but javafoil is showing Cl less than ...
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1answer
62 views

Does thin airfoil theory work at very high angles of attack?

Thin airfoil theory says that lift coefficient is directly proportional to the angle of attack in radians. I haven't been able to find any limit, short of stall, for applying this theory. It would ...
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2answers
856 views

Does an increase in lift always cause an increase in lift-induced drag?

An increase in lift causes an increase in drag. Is it always true? I am confused with two points. Lift increases with an increase in airspeed but induced drag reduces with an increase in airspeed. ...
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1answer
63 views

What is area in equation of lift?Does it remain constant during flight? [duplicate]

I am beginner & learning aerodynamics concept. What is area in equation of lift(L) =Coffecient of lift x area x density x square of velocity/2. Does increase in angle of attack increases the area &...
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2answers
124 views

Does bi-wings create essentially double the uplift as single wings?

This puzzles me a bit, and I cannot find the answer anywhere. Does bi-wings create essentially double the uplift as single wings?
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2answers
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How to calculate CL with the use of MTOW?

I have a problem that it gives us the MTOW of a UAV (200 kg), the speed and the reference area. So its probably easy to find the CL knowing that it flights at steady level flight (L = W). I'm confused ...
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1answer
136 views

How to find the static stall angle of attack for a given airfoil at given Re?

For vertical axis wind turbines applications I'm wondering how one would find the static stall angle of an airfoil at a given Reynold number? Is it just the critical angle of attach (AoA) where ...
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1answer
45 views

Is drag the only aerodynamic force that acts upon an asymmetric body (a glider in particular) travelling through the air?

It is known that for a symmetric body, like a sphere falling through the air, the only aerodynamic force that acts upon it is the drag that points always in the opposite direction relative to its ...
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1answer
107 views

Is the total lift of a quadcopter the sum of the lift from each propeller?

In this diagram each rotor R1,R2,R3,R4 has an individual lift force of 490 N. All combined, does the total force on this aircraft equal to 1960 N? The aircraft in question is similar to a quadcopter.
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1answer
69 views

Why the gradient of $C_L$-$\alpha$ graph increases with the Mach number?

From the JAA ATPL Book 13 (Principles of flight) the gradient $\frac{dC_L}{d\alpha}$ of the $C_L$-$\alpha$ graph increases for higher Mach numbers. Can someone explain why this is the case?
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2answers
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What is the amount of lift produced by friction?

As Mr. John D. Anderson states, the aerodynamic forces on a body are due to only two sources: pressure distribution over the body and shear stress distribution. Shear stress is acting tangential to ...
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1answer
156 views

What is boundary layer tripping?

I came across the term "Boundary layer tripping" but I can't really underastand it. After searching on internet I cannot find any video or an image explaining that concept. Could you please explain ...
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1answer
123 views

Tapered Wing Providing low Coefficient of Lift

Hi I am currently analyzing different wing designs using ANSYS Fluent. One of my designs has a straight leading edge but a swept trailing edge thus it is tapered with wing root chord at 50mm and wing ...
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2answers
165 views

How does an aircraft maintain an orientation that was actually caused by a external disturbance?

What is the difference between centre of pressure, aerodynamic centre and neutral point? At this link, there is an image used to explain the answer, but not much has been spoken about it. I ...
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2answers
683 views

Why do autogyros exist? [duplicate]

This question has been intriguing me for some time. In Autogyro the rotary blades merely acts as what fixed wings act in normal aircrafts to generate lift. So why not simply have a fixed wing instead ...
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5answers
193 views

Can lift be increased by increasing the angle of incidence of the wing? [closed]

Can the lift of a plane be increased by increasing the Angle of Incidence (angle between the chord line of the main wing and the axis of the fuselage)? Meaning, can more lift be generated while the ...
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2answers
133 views

Vertical autorotation with passive rotor

Let's say we have a simple hollow cube(chosen for simplicity) with outside side length=10cm, thickness=5mm (or another arbitrary shape with arbitrary dimensions). Clarification: I am NOT talking ...
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2answers
158 views

Would it be a good idea to use dihedral on a biplane?

My engineering class uses model plane kits to build "frankenflyers" which use parts from multiple model planes to make one plane that will carry a maximum load (pennies). I was wondering what the best ...
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1answer
86 views

At which angle tiltrotor's rotors generates more lift?

[Tiltrotor 1] [Tiltrotor 2] I can't name these tiltrotors. I just want to know which of the tiltrotors generate more lift considering aerodynamics and based upon the rotors ...
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0answers
60 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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3answers
215 views

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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0answers
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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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3answers
613 views

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
248 views

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
116 views

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
124 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
231 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
584 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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3answers
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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
153 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
75 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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0answers
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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
272 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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3answers
608 views

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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1answer
104 views

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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