# Questions tagged [aircraft]

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

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### Air flight and Earth's rotation

I read a response asking why flights of equal distance east and west take roughly the same time (disregarding wind actions). I have trouble visualizing part of the answer; "the speed of the rotation ...
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 ...
468 views

### Roll angle for banked turn of an aircraft on a tilted plane

It is known that for a banked turn of an aircraft on a plane parallel to the ground, the roll angle $\Theta$ computes as $\Theta=\arctan(\frac{a}{g})$, with $a=\frac{v^2}{r}$ the centripetal ...
388 views

### Plane landing into a tunnel

Typical action movies cliché is landing a plane in a tunnel or even a flight in a tunnel. Let's drop any doubts about supreme heroic piloting skills of the characters etc. and focus on aerodynamics. ...
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....
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 ...
74 views

### Is it possible that a plane in turbulences has more downward acceleration than gravity's

In multiple Hollywood movies and TV shows I've seen scenes where a plane enters turbulences and for a moment the people in the plane seem to move upwards relative to the plane. As far as I know, as ...
115 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 ...
34k views

### If the Earth is curved, why don't planes need to adjust attitude to stay parallel to the ground?

If I'm flying parallel to the ground and I never adjust my attitude, shouldn't my altitude above the ground start rising if the Earth is curving away from me? In practice, why doesn't this happen. ...
72 views

### Faster alternative to travel to any location in the west? [closed]

Suppose one needs to travel to Somalia from Indonesia(which are approximately at a distance of $4000$ miles from each other on the line of equator). To accomplish this task, I suggest the following ...
318 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 ...
299 views

### How to sensor Jerk=$d^3{\bf r}/dt^3$, or higher derivatives (4th, 5th, 6th order) when applied in the equation of motion of a ballistic missile?

Given a 6th order differential equation of motion as usually used in ballastic missile dynamic models. What kind of sensors are usually used to measure Jerk, (or higher order derivatives in kinematics)...
97 views

### How much energy would it take to take down a 747 using vibrations? [closed]

Background Information: All materials have a resonant frequency, which is the frequency at which they are most easily excited (vibrated). That's how glass is shattered using high-pitched sounds. ...
157 views

### rocket vertical landing [closed]

SpaceX has published a couple of videos that show one of their heavy-lift rockets landing vertically in a highly specific location. How is it possible that they are able to control so many ...
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 ...
79 views

### How do I figure out the totally airborne height for a given machine?

Technically "airborne" can just mean to move through the air, but I would like to know how high you have to be before you are entirely supported by air in a helicopter-like machine, as opposed to ...
558 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                &...
83 views

### Speed limit to air travel? [closed]

Is there a hard limit on the speed of air travel on earth? That is, if you consider the way the human body reacts to gravity. Is there active research ongoing in this area?
61 views

### Can an Adequately Long Tube Float?

I was just pondering in my head one day (I don't recall what I was pondering), but I came across the thought: If an adequately long (and light) tube is placed in the atmosphere, can the difference in ...
3k views

### Trying to understand jet engine [closed]

I'm trying to understand at a high level how a jet engine works. I want to know if the following summary I wrote is more or less accurate: The jet compresses regular air into a combustion chamber. ...
3k views

### Does laser beam expand along distance or not? [duplicate]

Why does laser dot become bigger at bigger distance? e.g: from millimeter to inches so that it distracts pilots in aircrafts. I knew that laser beam should't expand over distance, but remain stable. ...
1k views

### How thick does a spider web have to be to stop a 747 in flight? [closed]

There is an idea I've heard since I was a kid that involves the relative strength of spider web. The claim is that if it were something like an inch thick it could stop an airplane in flight. How true ...
212 views

### No need Power to fly ? Paradox [duplicate]

I would like to know how much power I need for magnetic levitation. $$P = Fv.$$ $F = F_g \approx \text{mass} \times 10$, okay. But $v = 0$! I can't believe I need no power to keep an object in the ...
35 views

### Fluid Dynamics applied to Aircraft wings [duplicate]

On aircraft wings, the bottom is flat and the top is curved. I know this benefits the aircraft by producing lift, but I wish to understand how. I'm told it has something to do with how fluids behave.
676 views

### Coriolis Effect vs airplane

So, if I build a highway from north pole towards equator and sit in a car, speed pretty fast towards it, I should feel force with the Earths rotation due to the different rotation speeds of this ...
278 views

### Why don't we build helicopter based space shuttles?

As seen in this video: the principle of the helicopter does work in space. So we could make a helicopter based space shuttle! It would be easier to navigate with it than with propulsors.
158 views

### Why is the water in a cup not inclined (opposite the cup) when the plane takes a turn?

When a aircraft takes a turn: Why is the water in a cup not inclined (opposite the cup)?
670 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?
4k views

### Is speed of propeller-driven airplane limited by the speed of sound?

Mine line of thoughts goes like this: A propeller is effectively pushing itself away from molecules of air. The best any propeller can do is to create total vacuum in the front of itself. The ...
939 views

### Since Earth spins, would an aircraft travelling opposite to direction of Earth spin take less time? [duplicate]

Suppose we want to reach the point on earth which in relative terms is exactly on the opposite end of the sphere we call earth (I know it is not an exact sphere). We either dig vertically downwards, ...
15k views

### Coriolis force on bullet vs airplane

Why do airplanes experience negligible Coriolis force while bullets experience the Coriolis force in long range shooting, even though the mass of airplane is much bigger than a bullet?
769 views

### How much power can support an object to float in the air near the surface of the earth?

If we want to float an object of 1KG in the air near the surface of our earth (the object can move slowly but shouldn't move very fast like a flying plane), at least how much power do we consume? I ...
123 views

### What is the top speed of the SR-72 aircraft? What affects would traveling at this speed have on the human body? [closed]

What is the top speed of the SR-72 aircraft? What affects would traveling at this speed have on the human body?
158 views

### Why is an airplane able to increase thrust without moving?

I was just watching some documentaries and saw planes building up power in the turbines without moving. I thought about it and remembered, that this happens before every take off. So, why is this ...
4k views

### If an airplane is flying sideways, is it in free fall?

If a plane turns 90 degrees such that it is flying sideways, is it accelerating towards the earth at the usual 9.8 m/s^2? My guess is that the plane must be in free fall because I don't see what ...
45 views

### How to approximate lag of roll of a bird (or RC airplane)?

When an airplane rolls using ailerons, the ailerons itself are changing their state quite instantly. However, in order for the airplane to actually start to roll, it should take a considerable amount ...
1k views

### Alternative air transportation and magneto-aerodynamics

Firstly, I am not a big fan of UFOs, however, a flying saucer makes me think if is there another, comparatively agile way to travel through the air without jets, turbines or propellers (balloons are ...
2k views

### When an aircraft flies over, glass window vibrates…Infrasound?

When an aircraft flies over, my big glass window vibrates, making a ticktack beating. Its frequency sounds low, less than 10 beats per second actually. I'm wondering about the mechanism of this ...
7k views

### Why do vapour cones form around jet fighters?

Apparently this phenomenon has nothing to do with jets breaking the sound barrier and has something to do with the Prandtl-Glauert singularity as described on Wikipedia. But, the Wikipedia article isn'...
2k views

### Speed of sound and Break the sound barrier [duplicate]

What happens when plane exceeds the speed of sound? and What is the interpretation of the conical shape that appears behind the plane?
389 views

### Airplane on a treadmill [duplicate]

I've heard conflicting answers, and would like to see the record set straight: An jet/propeller airplane is traveling on a giant treadmill at takeoff speed. Will the plane takeoff, or will it remain ...
557 views

### 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.
4k views

### What does a wing do that an engine can't?

This isn't a question of how a wing works -- vortex flow, Bernoulli's principle, all of that jazz. Instead, it's a question of why we need a wing at all. A wing produces lift, but why is that ...
100 views

### Why air above airplane's wing moves faster? [duplicate]

One explanation I read: Because of the wing's geometry, the "upper" side of the wing is longer, so the air has to travel faster: My wondering: Who said (and what was his/her explanation) that air ...
9k views

### Effect of Earth's magnetic field on aeroplanes?

As an aeroplane accelerates through the Earth's B-field, it experiences a changing flux $d\phi \over dt$ and a potential difference is induced along its wings. Given the wings are made of metal and ...
2k views

### 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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### When is the stress on an airplane the highest?

Something I´ve been wondering for a long time: At what point during a flight is the stress on an airplane the highest? Is it during take-off, landing or during (light/moderate/severe) turbulence? ...
791 views

### Pressure difference between 2 side of wings of aircraft

I understand why the pressure is reduced above the wings of aircraft, but when I read books and look for information, it says that the air is compressed below the wings, I do not understand why it is? ...
I have a relative motion problem in which I cannot get my answer to match the book answer. The question is: An airplane has to travel $189\, \mathrm{km}$ due east to point $B$ from point $A$. It ...