Questions tagged [aircraft]

Aircraft are man-made vehicles intended to operate while flying through Earth's atmosphere.

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0answers
6 views

Middle pitch of planes [migrated]

I’m french so excuse my english... I’m looking for the middle pitch of big planes like A300. For an horizontal travel, is the plane horizontal or does it have a pitch like 1 or 2° (or more)? If the ...
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3answers
670 views

Why ballasted gliders fly faster?

The fact: Gliders have ballast tanks that can be filled with water. The addition of ballast increases weight, and this allows the glider to fly at faster airspeeds while maintaining the same glide ...
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1answer
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What happens if a helicopter's propeller spins in reverse?

I know airplanes and helicopters fly thanks to the same principle, the Bernoulli Principle. The wings and blades are designed so that the air travels faster across the up side than it does on the ...
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How much at least should the Earth be smaller so that we notice these three phenomenons?

The Earth is moving with a speed of about $1670$ $km/h$ around its axis. This speed is more than the sound speed. So the Earth is always breaking the speed of the sound. How much at least should the ...
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1answer
101 views

Why can a helicopter fly upside down?

I saw images and video clips of helicopter flying upside down, so it can't be bernoulli principle or angle of attack of the rotary blades. So how can the upside down helicopter provide lift in this ...
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Drag and lift as a function of speed

Assuming turbulent flow, the drag force $F_\mathrm d$ and the lift force $F_\mathrm l$ are usually given in terms of the following equations $$ F_d\, =\, \tfrac12\, \rho\, u^2\, c_d\, A $$ $$ F_l\, =\...
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2answers
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Reason for lower air pressure above an airplane wing

I am posing this question from the perspective of a novice. I read an article, from Scientific American, titled "No One Can Explain Why Planes Stay in the Air". The article explains how, while we ...
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1answer
31 views

Fluid Dynamics (Air) Specifically Aeronautics

An airplane lifts off when the pressure of air pushing down on the wing is reduced due to the speed of the vehicle. Would it be possible to construct an airplane so heavy that it would be totally ...
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1answer
115 views

How does quadcopter's battery capacity relate to it's maximum flight time?

Suppose that we have a quadcopter weighing 3 kg (without a battery) and a battery (let it be Li-Ion type) weighing 2 kg. With this battery our quad can hover for 20 minutes until the battery runs flat....
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2answers
247 views

Forces acting on a helicopter

I was wondering about the force that a helicopter produces to descend to the ground being always upwards. How does that happen? I understand that it must be upwards but can't imagine it, how do the ...
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Problem involving the 4 forces that maintain an airplane in level flight

The 4 forces affecting an airplane in level flight are gravity, lift, thrust, and drag. By altering one, the others are affected. My question is could a wing (retractable) be installed on top of a ...
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Is the physics behind planetary travel simpler than atmospheric travel?

I've been watching a bunch of documentaries lately and had a question that I couldn't really figure out the answer to online. When spacecraft travel through space, are the equations and physics used ...
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How can Lift = Weight; if airliners fly with Thrust-to-Weight ratios = 0.3? [closed]

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
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Lift => Mass, for a helicopter in a hover; not Lift = Weight? [closed]

Background: According to Newtonian mechanics, a helicopter in a stable hover accelerates ('a') a mass of air ('m') downwards to generate a downward force; according to Newtons 2nd law (Force = ma). ...
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1answer
63 views

An interesting query about gravitation [duplicate]

If a helicopter flies linearly in the upward direction from a point A on the earth stays in the air at the same position for a long time and then linearly comes down , will it land at the same point A ...
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How much effect does the Bernoulli effect have on lift?

I understand that the Bernoulli effect is a flawed explanation for the cause of lift, and does not cause much at all, but how much? Is there any experimental data on the force caused by the ...
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If the aircraft has no inertia, how will it move after losing power?

If the aircraft has no inertia, how will it move after losing power? I think because of the aerodynamic force, the aircraft stopped moving immediately. Am I right?
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7answers
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Is the weight of the aircraft flying in the sky transferred to the ground?

Is the weight of the aircraft flying in the sky transferred to the ground? Is the weight of people swimming in the pool also transferred to the ground? How can we prove it?
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speeding up airflow over wings while keeping the propulsive efficiency?

So, let's say we have an aerofoil and we were to apply thrust at where the air speed was the greatest. See figure: Since we apply a thrust to the air it will speed up, thus reducing the pressure even ...
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4answers
290 views

The physics of airplane flight [closed]

Physics in schools teaches two contradictory and mutually exclusive things: (1) 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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5answers
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What causes the air speed difference above and below the wing of a plane?

I am studying about the lift generated by a fluid flowing on a surface. In the case of an airfoil I have seen that there are various ways to explain it, you can use for example: the third law of ...
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2answers
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Is a square tube more resistant to bending than a round tube?

In considering tubular forms for aircraft construction, I am reasoning that a square form (or I-beam) would be more resistant to bending (if the load is directly perpendicular and in the plane of the ...
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1answer
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Conservation of angular momentum on a drone

As I understand, a drone turns horizontally using conservation of angular momentum, accelerating rotors going to one side and deaccelerating the others. All the books I have seen about this say the ...
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1answer
77 views

What's 'force per second'?

For example, if a force of 10 N per second (10 N/s) is applied to an object, does this have a name or a definition? I'm not referring to impulse - which is Ns. An airplane's engine thrust is simply ...
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4answers
842 views

Can you “rewind” sound messages by going supersonic? [duplicate]

I was having a discussion with a friend about supersonic flights. It was then when he proposed an idea on an interesting experiment that can be done during a supersonic flight. The experiment goes ...
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4answers
108 views

Why don’t people on an airplane experience “weightlessness”?

People in the ISS feel weightless because they are in perfect orbit around the Earth, and only gravity is pulling on them. By that logic, why aren’t people in airplanes weightless? A plane stays at a ...
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Paper plane between two fans - is this possible?

The setup: two fans facing each other, distance around 1m. Both are turned on. In between them, place a simple paper plane and according to this video, it will fly. https://www.youtube.com/watch?v=...
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Ion Wind Thruster? What is the theory behind it?

I am 18 and I am a university student studying aerospace engineering. While I am looking up Elon Musk's Electric jet plane I found this http://inhabitat.com/mit-developing-ionic-wind-thrusters-as-...
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Why can't we fly aeroplane or shuttle directly into the space (beyond 100 km height above Earth's surface)? [duplicate]

Without rockets can we go beyond Karmans line by shuttle or plane?
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4answers
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Why do aircraft inner wings lose lift when turning?

first question here, so please be gentle! I'm reading an entry-level engineering course book and am currently up to discussion of aircraft design. There's one particular statement that is unclear to ...
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4answers
143 views

Why doesn't my flight aerodynamics maths work? [closed]

Context: For some context, I'm a game developer and I'm building a flight sim game. My goal is to have realistic flight physics -- not arcade physics. I'm having issues with the maths -- it is not ...
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2answers
93 views

Wouldn't the air accelerating over the top of the wing push the wing forward (thrust)

A wing accelerates air on top of itself. Does this cause any forward thrust? I would think so because the air is accelerating backwards which should create an equal and opposite reaction forward.
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Why Does A Ramjet Produce Net Forward Thrust

So every (non-technical) explanation of ramjets I've seen talks about how the intake slows and pressurizes the incoming air before combustion but then takes for granted the fact that burning fuel ...
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Nuclear-powered Ramjet + criticality

I came across this Wikipedia entry about Project Pluto; a nuclear-powered ramjet that the U.S. was developing back in the day. https://en.wikipedia.org/wiki/Project_Pluto This missile would have ...
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1answer
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Turning an airplane - coordinated turn and inclinometer (“the ball”)

I'm flying, turning in a stable orbit, i.e. at constant level with a constant angle of bank, at constant airspeed, with a constant radius of turn, as in the picture below: I am flying along the black ...
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2answers
273 views

Calculate work done by a hovering helicopter over time

This is likely to be very simple, but... How does one calculate work done by a hovering unmoving aircraft over time? As in work in Joules. In this scenario, to remain hovering the aircraft has to ...
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1answer
103 views

How much kinetic energy does a helicopter use in a hover? [duplicate]

A helicopter just circulates air in a hover and maintains a stable altitude. So, how much energy is used to do this? Using the standard equation $KE = \frac12 mv^2$; then the kinetic energy used would ...
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Center of lift in an aircraft

what is center of lift in an aircraft? How is it different from aerodynamic center and center of pressure? Why is COL important?
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Beryllium Vacuum Sphere Boat/Aircraft [closed]

Is it possible to make a solid rigid evacuated "balloon" out of Beryllium or other elements or alloys? The critical buckling pressure at which an evacuated sphere is given as $$ P_1=\frac{2E\cdot\...
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Why do jet engines sound louder on the ground than inside the aircraft?

Everyone is familiar with the whirring sound of jet engines when seeing an aircraft taking off from a nearby airport. It is distinctly very loud on the ground and one can hear it even when the ...
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1answer
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Why are the backs of airplanes curved?

I get the front part, but why is the back curved too? I do not see a problem with the back being flat.
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1answer
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Drawbacks of a Tip jet helicopter [closed]

A Tip Jet helicopter offers some advantages, i.e. eliminates transmission, torque is lower, etc. Engineers experimented with this design in 1950s, but remains marginal at best. What are the ...
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14answers
71k 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 ...
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1answer
111 views

Why is it a sonic “boom” and not a sonic “boooooooooooooooo…m”?

As I understand it, when an object pushes past the sound barrier, a sonic boom doesn't happen just once, but rather, continually (correct me if I'm wrong). So why is it that there seems to be only a ...
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1answer
330 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 ...
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1answer
50 views

Why an aircraft or a ship produce pressure waves both in front and behind them?

I think it is obvious why a pressure wave is produced in front of a moving object but why the rear of it should produce a wave?
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Is plane altitude limited by engine power and if so does air density cause this?

I notice that, for example, human-powered flight operates at low altitudes. This might of course be due to safety but I wonder if in fact the delta in air pressure is greater at lower altitudes and ...
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1answer
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Why do planes use 1-2 propellers in the front, but drones have 4 on top? [closed]

Planes with propellers normally have one or two propellers in front, facing forward, helicopters have one on top facing up and one facing the side, and drones have four on top facing up. How do the ...
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108 views

Do planes have to be noisy?

I tend to think of noise as an undesirable waste of energy because the generator was not designed for that purpose. But that doesnt mean this waste can be avoided. So I wonder how much of this noise ...
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2answers
577 views

How does gas spin the turbine in a jet engine?

I am confused about how the energy from the ignited gas spins a turbine in a jet engine, as pictured below                &...

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