Questions tagged [aircraft]

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

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1answer
92 views

Why is the polar diagram of an airplane depended on weight?

Can anybody answer this question? Although aviation-related, it is in fact a fluid mechanics problem: https://aviation.stackexchange.com/questions/54192/why-is-polar-curve-of-a-glider-dependent-on-...
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Sonic Boom in Aircraft and Spacecraft

I would like to know why aircraft, and spacecraft produce a double sonic boom on breaking the sound barrier. A while ago, I thought I got it, as there’s a start and finish point to every vehicle. ...
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1answer
69 views

what would a “ceiling effect” (the converse of ground effect planes experience) entail?

Wikipedia describes ground effect as "the increased lift (force) and decreased aerodynamic drag that an aircraft's wings generate when they are close to a fixed surface." That's all fair and good, ...
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4answers
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Effect of tailwind on aircraft speed

I have been spending some time in analyzing the impact of tailwind on the ground speed of the aircraft. My analysis is based around the following equation : VAW = VAG - VWG ; where VAW is the velocity ...
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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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When plane crashes

Could it be true that when the plane is falling to crash, one should start to jump. If the moment the plane crashes, you are in the air then, you are not affected by the momentum. That is very ...
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2answers
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How powerful can the vacuum from an open aircraft window be?

It has been an item of folklore that a "pressurized" aircraft cabin, if punctured will force people through the aperture, a la Goldfinger. However, obviously the pressures inside the cabin (12 PSI) ...
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73 views

Lightning strike on aircraft

Is an electromagnetic pulse sufficient to account for the complete dscharge of an aircraft struck by lightning?
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1answer
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How would I calculate the speed passengers 'jump' based on the speed and displacement of a plane during turbulence?

I read recently that if I'm in a plane that hits turbulence, the plane might only move 1 to 20ft. However, due to the speed that plane is travelling at (say cruising at 550mph). The passengers in the ...
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1answer
261 views

What does it mean that the weight is negative?

In a recent question on the Aviation Stack Exchange, one explained that would cause an autogyro's crash. Basically, it says that the one thing that would make the gyro crash is to unload the motor too ...
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Airplane trails

Some airplanes leave a trail through some regions of sky. This post explains why it is so, but it seems not enough. The trail is said to be made mostly of water which, on a specific altitude, ...
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Flying with or against rotation of a planet

So, I've read a bunch of articles about how, somewhat contrary to intuition, it's usually faster to fly with the rotation of the earth versus against it. All the answers have to do with wind and ...
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Would a plane get lighter if dry ice is inside and it sublimes during the flight?

During a series of comments here, it was suggested that taking dry ice into an airplane, the airplane gets lighter as the ice sublimes. This was supported by the idea that when the dry-ice sublimes ...
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Flow over Airplane Wings

I recently read this from Wikipedia in an article discussing lift. A fluid flowing over the surface of a body exerts a force on it. It makes no difference whether the fluid is flowing past a ...
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4answers
833 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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1answer
253 views

I'm confused about the aerodynamics of a gas turbine compressor blade of a jet engine?

I have a few questions here- Why do you need an increase in static pressure, why not total pressure? The rotor vane increase total energy, is this energy converted into kinetic energy or total ...
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1answer
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Could you build a “space tunnel system”? [closed]

With the limitation of fuel that can be taken on a space craft, would it make sense to build a propulsion system in space instead? For example via rings that are aligned very well and are positioned ...
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Cold airplane window frame

I was flying from Asia to Europe and noticed that the bottom of the window frame was ice cold while the top was warm. Why? My theory: The sunlight warming the air between the "inner window" and the "...
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Is Gyroscopic precession relative to the object in precessions axis of movement when there is drag imposed on the disc?

Does my question make sense? I am referring to the disc of an AutoGyro aircraft. Though the fuselage of a modern pusher AutoGyro will weather vane into the wind, the disc that provides lift does not. ...
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Why does a car need so much power to get to a given speed compared to an aircraft?

This question has been bothering me for a long time because it seems like it should be obvious, but I can't figure it out. Excuse me if I'm being dumb. Why does a car require so much more power then ...
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1answer
156 views

If Earth is curve and spinning, why plane flying in high altitude does not delayed?

If earth is spinning globe then the layer of athmosphere have a different tangential velocity for different altitude. For near the ground (solid surface of the earth) then the velocity of the air just ...
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2answers
239 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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0answers
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What are the 3 Euler angles?

I am currently reading up on inertial measurement in aircraft systems. Euler angles are one of the concepts I am a bit confused with. In an Euler angle-rate matrix there seem to be 3 parameters: p, q, ...
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Why don't aircrafts spin their wheels before landing? [closed]

I had this thought when I was on the aircraft when it landed in the runway. It made lots of smoke and all sorts of vibrations, you know. When I enquired about it, I came to know that the landing part ...
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Does a pilot have to take into consideration the angular spin velocity of the earth?

First imagine a pilot takes off from a North South runway situated on a specific northern latitude, the circumference of which is 888 miles, where the angular spin velocity of the earth (and the plane)...
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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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1answer
384 views

Reynolds number and shapes of airfoils

$$\mathrm{Re} = \frac{\rho \cdot v \cdot c}{\mu}$$ Where $\rho$ is the pressure, $v$ the velocity relative to the airflow, $c$ the chord of the airfoil and $\mu$ the air density. Does that mean that ...
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364 views

Why biplanes are not used in modern high speed aircrafts? [closed]

Explain why the high speed and commercial air crafts are monoplanes why not biplanes?
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213 views

Why does a tail make a kite more stable?

I have looking online to find answer to this question and one answer said that the tail increases drag and weight but, it did not say why the Increase in drag makes the kite stable. One theory I have ...
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3answers
359 views

Why Jet fighters don't heat up like spacecrafts?

After reading the answers to this question: After what speed air friction starts to heat up an object? I understood that the compression of gas is what generates heat that we see when a spacecraft or ...
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1answer
2k views

Why does an increase in angle of attack cause the boundary layer to slow down?

From what I understand when the angle of attack of a wing is increased enough the boundary layer air slows down. Eventually the air starts moving backwards and a separation bubble occurs. Why does the ...
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2answers
656 views

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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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 NASA need an aircraft model flying over a flat and nonrotating earth?

On the NASA Technical Reports Server (NTRS) there's an article titled Derivation and definition of a linear aircraft model: Abstract A linear aircraft model for a rigid aircraft of constant ...
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What does “relatively uniform resonant frequency” mean?

In the book What If? from Randall Munroe, the author writes: Q: Assuming a relatively uniform resonant frequency in a passenger jet, how many cats, meowing at what resonant frequency of said jet, ...
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Does the temperature of the body of an aircraft increases its efficiency?

I am actually working on a prototype of a Plane, i was wondering if the temperature of the body of the plane can make the Plane more efficient, if the structure is at 25°C needs less energy to ...
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2answers
113 views

Power of pressure difference

I was watching an airplane taking off when this question suddenly came to my mind: How can we estimate the pressure difference between the wings of a jet ? I think it must be immense since it needs ...
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2answers
695 views

Would an electromagnetic jet engine work? [closed]

If the front fan on a gas turbine had a blade, or some of its blades extending into the surrounding housing, where there was a maglev ring of electromagnets, could fuel use be reduced by the engine? ...
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1answer
637 views

Does aeroplane moving against Earth's rotation cause relative wind (assuming otherwise a quiet weather outside)?

Although, I know some answers, I need more affirmative and accurate answers. Why is the journey time from London to Singapore less compared to Singapore to London? Is it because of Earth's rotation ...
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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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1answer
94 views

Aeronautical Physics induced drag direction

I am a 9th grader doing a science fair project at my local high school. I am doing a science experiment on different plane wings and how the angle of attack affects drag. I need to create a rig to ...
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Does a rope connecting an object to a constant-velocity aircraft fly at an angle?

A massive object is hanging by a massless cord from an aircraft. The aircraft is moving at a constant velocity v. Even assuming that air resistance exists, shouldn't the cord be perpendicular to the ...
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Forces on ball thrown inside fighter cockpit during a manoeuvre

In a fighter aircraft, if pilot throws a ball vertically inside cockpit, and carries out a '6 g' turn, will the ball also undergo 6g force?
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Metal Lattice & Aircraft [closed]

So I have been doing some reading up on emerging technologies in the aerospace industry and I stumbled upon something interesting. Apparently, some researchers have developed an extremely light yet ...
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3answers
257 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 ...
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1answer
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Fan blades of jet engine [closed]

I recently watched video of rolls-royce jet engine manufacturing. There they showed that they measure frequency of each fan blade. Why they did so? What is need of it?
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How could this small nuclear reactor power two jet engines?

In the 1950s, the US was working on an Aircraft Nuclear Propulsion and it is stated that they successfuly operated two modified General Electric J47 jet engines using a 2.5 MW (thermal) nuclear ...
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Can a statically charged object flying in an airplane float?

Lets say you are flying in a plane headed due west at 1000 km/h (278 m/s) with an altitude of 10km. According to http://www.ngdc.noaa.gov/geomag-web/#igrfwmm, at 10km altitude, Earth's magnetic field ...
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672 views

Can a helicopter fly with just one blade? [closed]

I read somewhere that the main helicopter body will also spin in the opposite direction to maintain angular momentum, is this true?
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171 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 ...