Questions tagged [aircraft]

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

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8 views

Compression limits of hypersonic air

I'm finding my way around a bit in the realm of super/hypersonic flight particularly around sc/ramjets. The question is thus: What is the theoretical upper limit for air compression on a sc/ramjet and ...
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If I overvolt a server fan and put it on a model plane, will the plane go fast enough to take off? [closed]

Suppose I made a model plane with very light materials and small wheels. If I put an overvolted server fan and Li-ion batteries to power it and a raspberry pi, will it reach takeoff speed?
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61 views

Why does Wind Velocity over a wing to increases and what is its cause?

Why does wind velocity increase over a wing? Also I have a bit of a paradox, people explain lift by saying there is a lower pressure region on the top of the airfoil and a higher pressure region on ...
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93 views

What is the bare minimum of air density you need to fly a helicopter?

How high will a helicopter be able to fly before the propellers have not enough air particles to achieve lift? What is the minimum air density needed to achieve flight with a helicopter? Could you ...
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Why doesn't the static pressure in a jet engine change if the outside of the engine is cooled?

Why doesn't the static pressure in a jet engine change if the outside of the engine is cooled? Usually pressure goes down with temperature.
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Why is the propulsive force related Coriolis term ignored in flight dynamics (rocket equation)?

Consider a variable mass vehicle body $B$ with it's center of mass $B$ stationary with respect to the body fixed referenced frame $B$. We obtain the translational dynamics of the variable mass body as ...
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1answer
30 views

Swords and wing flutter

In order to retain structural integrity it is understandable that a sword has to be flexible enough to be able to absorb impact without shattering and rigid enough to not be bent due to it. Is this ...
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397 views

Yet another airplane question

The point of discussion here is the pressure distribution across an airfoil. In order to simplify the question, I'd like to consider an airfoil which looks like a triangle wedge with the blunt face of ...
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Pressure drop on diver and airplane against acceleration

I'm curious about the relationship between the pressure drop an object is experiencing and the acceleration it is experiencing. From book Frank 8ed Fluid Mechanics, this equation show that sum of per-...
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1answer
41 views

How to derive the bank angle of an aircraft from its roll angle and pitch angle?

From Young (2017) (https://onlinelibrary.wiley.com/doi/book/10.1002/9781118534786) it is stated that we can define the bank angle ($\Phi$) of an aircraft as the angle between its Y body axis and the ...
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How does a ram-air parachute move forward?

I'm trying to understand the "physics" behind the flight of a ram air parachute, Do you know / how could I know, whether the main parameter that makes a ram-air parachute move forward is: ...
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Plausibility of underwater planes [closed]

Wood floats on water because its density is lower than water. A ship made of steel floats on water because the ship is hollow, the overall density of the ship is lower than water. Now if you seal the ...
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Why is it that we ignore height difference when applying Bernoulli in an airfoil

I learn physics myself and sorry if this is a very simple question Why is it that we can apply Bernoulli on above and below the plane even if the are not in the same streamline? Why do we ignore ...
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Lift on Airplane wing

Why commercial airplanes use long, slender wings? Isn't it to maximize lift, we make the plane's wings as wide as possible?
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How to calculate the electric field strength in between asymmetrical capacitors?

For a school project I am trying to calculate the thrust to power ratio of the electroaerodynamic drive aircraft invented by MIT. See this article on the MIT News web site for details. I need to know ...
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179 views

Can we make a drone fly on the Moon by using cylinders with compressed air (or cold helium)? [closed]

Suppose we want to make a drone fly on the Moon (the gravity on the Moon is 1/6 of that on Earth), only by making use of its rotors and air. The drone is as light as possible ($m_{min}(kg)$, has ...
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Wind tunnel experiment that measures lift (not the lift coefficient)?

Does anyone know of a wind tunnel experiment on a wing or airplane that measures the absolute amount of lift (not the lift coefficient); and demonstrates conclusively that the lift generate by a wing ...
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2answers
55 views

Can an airship tack? [closed]

A sail ship leverages the keel’s resistance to turning moments to allow a wind crossing a sail at an angle to tack, achieving a speed greater than the driving wind. But is it possible at all for an ...
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What causes the Coandă effect? [duplicate]

What causes the Coandă effect? Here's my understanding of it: When a fluid flows around a curved surface it has high velocity and so low pressure its pressure will be lower than the atmospheric ...
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1answer
121 views

Effects of altitude on paper airplanes

If one were to fly a paper airplane at the Dead Sea (400 meters below sea level) and another identical paper airplane at the peak of Mount Everest (8800 meters above sea level) would there be any ...
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2answers
61 views

Why do airplane wings have fins?

I was watching this video and it shows that adding fins on the wing helps the air get turbulent on the upper part of the wing, which forces the air to stay longer, and ultimately this helps with lift. ...
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Heat dissipation in space - how do they do that?

Consider a space aircraft. During its propulsion, I believe a lot of heat is transmitted to the aircraft by simple contact with the motor. But in space, there is no air to cool the aircraft. The only ...
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1answer
110 views

Why are turbines more effective than propellers on airplanes? [closed]

I have read this question: Why do turbine engines work? The compressor generates a certain volume of air at a high pressure. In the combustion chamber, this air is heated - this leads to a much ...
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Why are aerodynamic / streamlined shapes always stumpy at the front?

I'm building an autonomous boat, to which I now add a keel below it with a weight at the bottom. I was wondering about the shape that weight should get. Most of the time aerodynamic shapes take some ...
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Calculating (transient) rate of cycles of practical thermodynamic engines (turbojet, multi-cylinder car engines etc..)

I tried to make a plan for a turbojet engine with my physics knowledge and I'm stumped in the first step. For any sustained real engine, I need to somehow take a fraction of the energy output and use ...
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1answer
37 views

Induced emf over the cuboidal wing of an air plane due to Earth's magnetic field

If the wing of an air plane is cuboidal in shape, and that the Earth's magnetic field $\bf{B}$ is uniform in the neighbouring volume of the plane, does that mean the induced emf over the entire 'block'...
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Model (or approximate model) of drone take-off forces?

I would like to implement a model of the force/uplift the floor makes in a multicopter take-off, but I don't find any info of this exact dynamic. Is there any paper that tackles this issue? Or any ...
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49 views

Why is pressure over the wing lesser than the pressure on the bottom? [duplicate]

Why is the flow above the wing faster than the lower one? Most people say it's because the pressure above is lesser than the bottom one But for the pressure to be low... The velocity must be high.So ...
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How are coefficients of equation of sideslip angle in the paper “A general Solution to the Aircraft Trim Problem” calculated?

I am sure many of you guys(Aerospace related) must have read the paper, "A General solution to the Aircraft Trim Problem" by Marco, Duke and Bernt. I am working with the turning of the Aircraft and I ...
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2answers
48 views

How does pressure become velocity in a jet engine axial turbine?

All right. Here's what I understand about axial turbines: It is an axial compressor in reverse. An axial compressor forces air to flow in an increasingly tight space, where there is not enough ...
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48 views

How can a fighter jet pilot pour water from a bottle to a cup without spilling while doing barrel rolls?

I came to watch two videos related to fighter jets, one in which the pilot pours red bull in a glass and another in which pilot pours water from a bottle to cup while doing rolls and while being ...
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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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146 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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140 views

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
34 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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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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244 views

Can anyone explain this thrust - weight - lift paradox for airplanes? [closed]

Engineers are confronted with two apparently true but contradictory statements: a) Lift must equal the weight of the airplane (Lift = Weight), based on Newtons 2nd Law of motion (i.e. Force = ma); ...
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1answer
155 views

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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68 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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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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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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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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219 views

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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3answers
480 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
344 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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51 views

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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171 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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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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267 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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