The force on a body moving through a fluid that opposes the force of gravity.

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2answers
112 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. ...
-1
votes
2answers
1k views

Why does the higher pressure of air underneath an aeroplane wing keep it flying?

With aeroplane flight, the wings are shaped so that the air that goes over the top of the wing has to travel faster than the air that goes below the wing. This means that the air below the wing has ...
0
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1answer
30 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
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2answers
42 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
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3answers
34 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
42 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 ...
4
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3answers
3k views

How much lift does an airplane get from its wings, vs the rest of the airframe?

Consider a big commercial airliner, like a 727, 747, or a 787. At cruising altitude, under standard conditions, how much of the lift of the aircraft comes from the wings, and how much from the rest ...
-2
votes
1answer
33 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
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3answers
50 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 ...
18
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2answers
5k views

Why don't rockets tip over when they launch?

Rockets separate from the launch pad and supporting structures very early in flight. It seems like they should tip over once that happens. Why don't they tip over ? Is it due to a well designed ...
4
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3answers
10k views

How much lift does the average latex helium filled party balloon produce?

How much lift does the average helium filled party balloon produce? (not including any extras like ribbon string)
0
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1answer
39 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 ...
2
votes
3answers
842 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
4answers
431 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
35 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
99 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 ...
167
votes
10answers
37k views

What really allows airplanes to fly?

What aerodynamic effects actually contribute to producing the lift on an airplane? I know there's a common belief that lift comes from the Bernoulli effect, where air moving over the wings is at ...
0
votes
0answers
27 views

Lift provided to an aeroplane [duplicate]

We say that aeroplanes find lift due to an effect explained by Bernoulli's theorem. But isn't newton's third law of motion applicable along with Bernoulli's theorem? otherwise, an aeroplane wouldn't ...
5
votes
5answers
500 views

Can a balloon be used as an anchor point for a pulley?

For a physics/ engineering contest, I want to use a large balloon as an anchor point for a pulley. This would allow me to raise and drop masses. However, in testing, when I pull on the pulley the ...
0
votes
1answer
33 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
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3answers
114 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 ...
13
votes
8answers
6k views

Does it take significantly more fuel to fly a heavier airplane?

I was reading in the papers how some-airline-or-the-other increased their prices for extra luggage, citing increased fuel costs. Now I'm a bit skeptical. Using the (wrong) Bernoulli-effect ...
8
votes
4answers
14k views

How does the 'water jet pack' work?

So I was cruising around at YouTube and saw this sweet video, and as I was watching started to wonder: "How is this possible?". For a little bit of background, in case you decide to not watch the ...
3
votes
1answer
215 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 ...
2
votes
3answers
1k views

Are the hypotheses of the Bernoulli equation satisfied for a bird or airplane wing at low Mach number?

A previous question by David Zaslavsky was a request for a broad, "how things work" type of explanation of the lift of an airfoil. The answers given there are enlightening, but don't address a more ...
5
votes
1answer
115 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 ...
0
votes
0answers
148 views

Magnus effect, Coanda effect, and the Bernoulli principle: What is balancing gravity on a spinning sphere vs. a stationary screwdriver?

I've seen videos of golf balls and screwdrivers levitated by a focused air stream. Reading the comments of these videos (and others), I see explanations of the machanics at work and their cause and ...
3
votes
3answers
152 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 ...
8
votes
1answer
480 views

Could the phenomenon of vortex bursting be exploited to reduce wake turbulence?

One of the classic stories in the annals of aerospace engineering is the development (and subsequent redesign) of the F-18 and its Leading Edge Extensions (LEX) due to fatigue problems, problems that ...
1
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3answers
584 views

Forces on an aircraft - thrust, lift, drag, weight

I'm extremely sceptical about the wikipedia page on aircraft flight mechanics. When describing 'straight climbing flight', it says: lift is unable to alter the aircraft's potential energy or ...
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vote
3answers
114 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 ...
4
votes
2answers
3k 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 ...
2
votes
2answers
666 views

Do wind turbines convert the kinetic energy of air?

It is often said that wind turbines convert the kinetic energy of the wind into electricity. But in respect to horizontal wind turbines with airfoil shaped blades this is imho not the case. Wind ...
1
vote
0answers
47 views

easy way for lifting 40 kg from fourth floor [closed]

i'm learning industrial design, my final project is a devise that can lift up the groceries easy, in buildings without elevator. the device will be placed on the window or on the flour and a bsket ...
2
votes
1answer
278 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
235 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 ...
3
votes
2answers
288 views

Counter rotating propellers: better in same column or staggered?

In an octo-copter design, is it better to put four pairs of counter-rotating props over each other so that each pair works in a column together? Or will you get more power or efficiency from ...
2
votes
3answers
349 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
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2answers
548 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 ...
0
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0answers
30 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?
3
votes
1answer
189 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
88 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 ...
3
votes
1answer
311 views

Is this xkcd comic feasible? [closed]

I was reading through some xkcd comics, and I came across this one (http://xkcd.com/620/). In the comic, one of the main characters harnesses 91% his weight in order to be able to 'fly' with the lift ...
0
votes
1answer
102 views

Is there a way to convert CFM (rate of air moved) to kilograms of lift generated?

Is there a way to convert CFM as in a rate of volume of air moved to kilograms of lift generated?
1
vote
0answers
31 views

Period of a pendulum in a lift going up [duplicate]

So I know that the period of a pendulum in a free falling elevator isn't going to change because there is no force acting on it since $$T = 2\pi\sqrt{\frac{\ell}{g}}.$$ So what happens to a pendulums ...
10
votes
2answers
5k views

Calculating the force required to lift a weight with a screw

I am trying to learn physics by myself as I do not have a good teacher at school. I've been reading Feynman Lectures on Physics and I can't figure out how he found out this number. Here is an excerpt ...
0
votes
2answers
188 views

Why can't we fly? [closed]

Why can't we fly? It contradicts with our known laws of physics, but which one? Is it possible that once we know gravity better we would be able to fly using some sort of anti-gravity machines like ...
2
votes
1answer
126 views

Measuring small amounts of lift in a wind tunnel

I am doing a science project on how paper airplanes generate lift, and I need to know how to measure the amount of lift generated by the plane.
2
votes
4answers
311 views

How does the position of lift affect the stability of the lifted object?

Consider this example: Treat G as 10. The blue blocks provide lift of 10N, or -1KG. The red block has a weight of 20N, or 2KG. The black bar has no weight. All have their center of gravity in ...
6
votes
1answer
3k views

What is a Physically Accurate Explanation for the Kutta Condition?

Countless arguments between highly intelligent people have been waged (on this very site in fact) as to exactly how lift can be explained in an experimentally and mathematically rigorous way. Taking ...