Questions tagged [lift]

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

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1answer
60 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
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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
229 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
93 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
51 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
796 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
58 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
121 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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119 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
43 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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2answers
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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
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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
121 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
111 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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1answer
74 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
669 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
190 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
125 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
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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
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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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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
193 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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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
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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
234 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
112 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
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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
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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
467 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
363 views

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
146 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
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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
259 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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576 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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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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1answer
105 views

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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1answer
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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
285 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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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
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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
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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
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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
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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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