We’re rewarding the question askers & reputations are being recalculated! Read more.

Questions tagged [lift]

Lift is the aerodynamic/hydrodynamic force on a body moving through a fluid that opposes the force of gravity. DO NOT USE THIS TAG for elevators. For aerostatic/hydrostatic lift in fluidstatics use the [tag:buoyancy] tag instead. For EM forces use the [tag:levitation] tag instead.

Filter by
Sorted by
Tagged with
1
vote
1answer
3k views

Why is a piece of paper lifted upward even when blown below?

According to Wikipedia, A correct explanation of why the paper rises would observe that the plume follows the curve of the paper and that a curved streamline will develop a pressure gradient ...
1
vote
0answers
82 views

How to calculate lift and drag of a non-standard aerodynamic body

It is my understanding that the standard method to calculate the lift and drag characteristics of an airfoil is to use formulae and existing data of its coefficients of lift ($C_l$) and drag ($C_d$). ...
0
votes
1answer
57 views

How many calories are burned by lifting 80 kilos once?

After some calculations i figured it was something like 192 kilocalories but it sounds a bit too much so im not sure if i did the right calculations. What i did was calculate the work and then convert ...
1
vote
0answers
53 views

What are the mathematics behind a disc being elevated by air flow?

I realize the question title is a little vague... I was at the Smithsonian air and space museum recently and they had a set-up showing a disc with an air pipe. The pipe is flowing air fairly ...
2
votes
2answers
391 views

Why does the wind speed increase when streamlines approach each other?

In my physics textbook, there's a chapter on fluids which discusses pressure, flow rate, continuity, and the Bernoulli effect. I understand why pressure gradients induce net force on a column of fluid ...
3
votes
2answers
1k views

Why does a rocket spin during launching

Why does a rocket spin during launching? https://www.youtube.com/watch?v=BuPY5l45UC8
0
votes
2answers
100 views

Lifting force applied to an object

The question is as following: Identical $K$, $L$ and $M$ containers have liquids with densities $d$, $2d$ and $3d$ respectively. A solid object with density $d$ is being dropped in all of ...
2
votes
1answer
481 views

Does the rotation of a frisbee have any noticeable effect on the frisbee lift?

If you throw a frisbee horizontally (with zero attack angle), the only uplifting force comes from the rim, which makes the air above the frisbee move faster and thus (Bernoulli) decreases the pressure ...
1
vote
1answer
7k views

Dimensional Analysis: How to choose the repeating variables?

The aerodynamic lift (force) $F$ that acts on an aircraft to support its weight when at cruise conditions depends on the following quantities: the speed of the aircraft relative to the air (the "air-...
1
vote
3answers
557 views

Downwash created by horseshoe vortex at zero travelling speed?

This is a simple aerodynamics question about the horse shoe vortex. As it seems, the trailing edges on the side cause the downwash on the wing of the plane. However, since the circulation is constant, ...
-1
votes
1answer
122 views

Would this chambered cylinder be possible? [closed]

Could a flexible light weight chambered cylinder (looks similar to bamboo) was filled with helium and stood up to reach outside the atmosphere? Each chamber would have a different psi according to ...
1
vote
0answers
94 views

How to calculate the amount of psi needed to pull a 150lb object? [closed]

I am working on a project, and I wanted to know how to calculate the amount of psi I would need to apply to a wheel-like mechanism (Like in a pneumatic torque wrench) to be able to pull a 150lb object ...
1
vote
3answers
248 views

How does the wing area affect the form drag and induced drag? And also lift?

I did an experiment of 8 different square wing areas. And found out that as the wing area increases, the wing vibrates more. (I made the wings out of hard paper) Does this mean that this is due to ...
1
vote
0answers
227 views

How does the “lifter”/ionocraft device work? [closed]

A while ago I watched a documentary which at the end (don't let the name mislead you, I'm asking about a perfectly real phenomenon) shows an experiment which its inventor calls a "lifter"/ionocraft. ...
1
vote
1answer
143 views

Calculate or Simulate the lift force of different rotor designs

I want to compare different blade shapes and rotor designs in their lift force and torque by a specific rpm. For a calculation, I would need the lift coefficient, which i don't have for a self ...
4
votes
4answers
15k views

How is lift generated due to Coanda effect?

I can understand the generation of lift via Newton's 3rd law but I cannot understand via Coanda effect. I watched a video on YouTube that said that for the upper side of the aerofoil the pressure will ...
-2
votes
1answer
487 views

What is the mechanism of a jackscrew? [duplicate]

According to Wikipedia: In the form of a screw jack it is commonly used to lift moderately heavy weights, such as vehicles. More commonly it is used as an adjustable support for heavy loads, ...
1
vote
1answer
157 views

How find/estimate Parasitic Area (CDA) in order to calculate V(L/D)max?

I am trying to calculate the speed which maximizes lift/drag for an aircraft. Using Carson's paper, it looks to me like the only unknown variable is "f", the parasitic area, which Carson describes as ...
1
vote
1answer
172 views

How the wing creates lift? Why critical angle of attack is 16.5" for a supersonic jet and a kite?

I have seen many references on how the wings create lift, most of them overplaying effect of Bernoulli's rule. But nowhere has there been any consideration given to this important factor: Let's ...
2
votes
2answers
2k views

How is determined the shape of the wings of an airplane?

My understanding of the reason why a plane fly is summarized by the following figure: because the upper part of the wing is curved, the air above the wing has to flow faster than the wing below. This ...
0
votes
1answer
85 views

Flying with the help of Coriolis force

I had just started to learn about Coriolis force and an interesting thought occurred to me. Can you fly with the help of Coriolis force because when you run Coriolis force acts upward and the angular ...
1
vote
2answers
354 views

Intuitive explanation for lower pressure above airfoil

From Bernoulli's principle we know for an incompressible fluid (constant density $\rho$) in a gravitational potential $\psi=gz$, that we can state the equation along a streamline from point 1 to point ...
0
votes
1answer
166 views

Can drag force and lift force be in the same direction in the following case?

In the attached picture, can I say that there is a lift force in the Y-direction, and a drag force too in the same Y-direction? $F_L$ proportional to $V_fx^2$ ? $F_D$ proportional to $V_py^2$ ? Is ...
0
votes
1answer
118 views

what causes airborne bodies to tilt?

Imagine a Helium-inflated oblate spheroid floating still (A). Buoyancy force cancels gravity force on Y axis. Object is tied to ground with a rope. If a wind force is applied on X axis, why does the ...
0
votes
2answers
335 views

Helium Lift Potential [closed]

A particular mass of helium is required to lift a particular weight. If the weight stays the same and the mass of helium is decreased can the same lift force be achieved by increasing the ...
0
votes
3answers
103 views

Modelling an Airplane Question

For an assignment of mine I am creating a very basic model of an airplane, where I choose to consider a fixed amount of parameters that affect flight and to disregard others which I find too difficult ...
1
vote
0answers
49 views

How is pressure reduced on the upper part of an aircrafts wing? [duplicate]

I have heard part of the explanation and that is that air on the top part of the aircrafts wing wants to move in a straight line, but the air is pulled down the slope or camber, but that's as far as I ...
-1
votes
1answer
109 views

Proper explanation of the hydraulic lift [closed]

How is hydraulic lift useful? According to energy conservation it is not possible. Can somebody please explain how a hydraulic lift works?
0
votes
3answers
109 views

2 airplanes same size and shap different mass

2 identical balls of different mass dropped from same height reach the ground at the same time due to the acceleration of gravity being constant. If I understand correctly the ball with more mass ...
0
votes
1answer
284 views

Aircraft Thrust to weight ratio contradiction with energy conservation

Usually, airliners have (Thrust/Weight) T/W ratio in the range of 0.2 to 0.8 and for steady flight W = lift My question is, for example, that Antonov 225 has Thrust/weight: 0.234 for max takeoff ...
9
votes
2answers
376 views

Can the Arcaboard fly?

Recently, BBC news had a video that claimed to show a "real" hoverboard: As far as I can tell, there are 36 small fans on this device, and it seems to be flying just a few inches off the ground. But ...
3
votes
4answers
11k views

Why does moving air have low pressure?

According to Wikipedia lift in an aircraft is due to an area of low pressure formed above the wings of an aircraft due to the fast moving air there. So why exactly is an area of low pressure created ...
0
votes
1answer
83 views

Aircraft lift theory vs energy conservation [closed]

I spent years trying to find out that when an aircraft flies or anything works it consumes energy more than it delivers back, means no perpetual motion exists. My query is that when an aircraft is at ...
1
vote
2answers
1k views

Is it feasible to lift a human off the ground with a suit of fans? [closed]

So, we live in a world that is technologically developed enough where it is reasonably within reach to attach small rockets to someone/something to lift it off the ground. One serious problem we ...
9
votes
1answer
4k views

How strong must a tornado be to pick up a shark?

Yes, you know where this is going. There is a good article on this topic by National Geographic: 'Sharknado' Got One Thing Right: Aquatic Animals Sometimes Do Fall From the Sky One of the first ...
1
vote
1answer
299 views

What is the lift coefficient and why is it important?

Why is it that there are numerous experiment on determining the lift coefficient of a tennis ball. Does the value have any use or show us anything about the ball?
0
votes
3answers
596 views

Can Bernoulli fly a car?

I need to settle an argument. How much influence, if any, does the Bernoulli principle have in sending a stock car traveling at 200 MPH sailing through the air when the air pressure unexpectedly ...
5
votes
1answer
650 views

Levitating capacitor

As the title already says, I would like to make a large capacitor levitate. Before you dismiss this question please hear me out: In essence, this is intended to be a way to avoid the constrains of a ...
3
votes
3answers
337 views

If gravity were to suddenly change, would the lift generated by a airfoil also change [closed]

If gravity were to suddenly change, would the lift generated by a airfoil also change? I realise that if gravity were to increase, then weight would also increase, leading to a change in the ...
2
votes
3answers
5k views

How many grams of helium are required to lift an object weighing $X$ grams?

I once saw a video on youtube about how a man used a collection of balloons to lift himself along with his lawn chair from one side of Los Angeles to the other. My understanding of physics is a bit ...
1
vote
3answers
380 views

Can lift contradict conservation of energy?

In cruise flight of an aircraft lift does no work, it just holds the aircraft aloft. In order to climb aircraft pitch up and need excess energy because the thrust vector now has a vertical component ...
2
votes
1answer
977 views

How does a hovercraft hover, if it has low pressure underneath it?

I've read a few different explanations of how hovercrafts hover, and they all mention a low-pressure cushion of air. This confuses me though: If there is low pressure under the hovercraft, why doesn't ...
1
vote
2answers
769 views

Do rotating non-circular projectiles also experience Magnus lift?

The Magnus effect has been studied on spherical projectiles such as golf balls, tennis balls, and soccer balls. The backspin of a golf ball leads to Magnus lift that opposes gravity, thus allowing the ...
2
votes
3answers
665 views

Is fuelless aviation possible?

I've read the article Gravity powered aircraft flies with no fuel. This is making me confusion, as I can not discern if it is credible. Is it an hoax?
1
vote
2answers
9k views

Given airplane mass, velocity of air under wing, and a wing area, find velocity of air over wing

I attempted to solve this problem as a tutor for a student and struggled, but want to be convince the professor didn't provide enough information. The problem is essentially: We wish to maintain a ...
1
vote
0answers
46 views

How can a rotating cylinder produce lift? [duplicate]

In the air, the velocity and angular momentum that causes a force against gravity is lift. How can a rotating cylinder make lift with angular momentum?
8
votes
3answers
11k views

Is Magnus effect a corollary of Bernoulli principle?

Magnus effect is commonly explained using Bernoulli principle. However, taking the lift on a rotating cylinder as an example, the velocity difference is caused by the extra work done by the rotating ...
3
votes
1answer
437 views

Understanding equation for force acting on stones skipping over water

I think I have a decent conceptual understanding of the forces at work when stones are skipped over water. My question pertains to this equation, $$ F = C_L\rho U^2S\sin({\alpha + \beta}) $$ which ...
3
votes
1answer
901 views

Force Keeping Water Skier Afloat

A motionless water skier sinks because the upward buoyancy force on the skier is less than the downward force of gravity on the skier. A skier pulled by a boat does not sink into the water. Why?
2
votes
1answer
116 views

Am i trying to fly by pulling myself up by my hair? [closed]

I'm currently trying to build a multi-rotor of my own, and am testing it when i noticed that the lift that i am supposed to be getting is wayy less than what i am expecting. I have a rectangular body ...