Questions tagged [aerodynamics]

A subset of the [fluid-dynamics] tag concerning primarily forces such as lift and drag generated on bodies as they move through gasses or as gasses move through the body (typically air).

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2D to 3D Non-Elliptical Lift Curve Slope Correction Factor Reference

I'm not sure this is quite the right network for this question but it also seemed like a reach for the aviation community. I'm working on automating some aerodynamic calculations for a particular ...
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Could a heated coil with a sail to catch the hot air,(in theory) produce enough or any thrust to lift a drone? in the way a hot air balloon works

This is an approach I am thinking of for an alternative to ion propulsion for making silent drones.
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What is circulation, regarding a wing, and why does it happen?

I was wondering, in layman's terms, what causes circulation around a wing? I understand that flight is a combination of Bernoulli's theorem and Newton's third law. The Coanda effect and Kutta effect ...
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In theory, how fast could I possibly serve in a game of ping-pong?

A tennis player can serve in a more or less straight line from their racket to the service box on the other side of the net: there's a direct line of sight. That means that there's no inherent limit ...
1 vote
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NACA Profile Approximation

Is anyone aware of any research that explores the characteristics of symmetrical NACA rudder profiles that are approximated using polygonal cross sections with few vertices (<20 per face) e.g.
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Can you avoid the cubic velocity-to-drag relationship by covering the entire surface with wheels?

If the object traveling through air is covered entirely in freely spinning small wheels (or ball bearings), then those wheels will begin to spin in accordance with the drag force felt by them. Once ...
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What about negative (absolute) pressure in Bernoulli Equation

I'm studying Aerodynamics and I'm thinking about the Bernoulli Equation Statement. Ignoring gravity contributes, it states that, in a potential fluid, the sum of static pressure and kinetic energy (...
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Lift force equation of a rocket and Lift curve slope

I'm trying to determine the lift curve slope of a rocket to get the lift coefficient, using L/qA . the lift equation I'm using is thrust-drag-mgsin(alpha). to me this seems correct as it essentially ...
1 vote
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Why doesn't an air valve move automatically when placed on a zero friction surface?

Air pressure is actually a force experienced by the surface of the container when air molecules hit it in high speeds. An air valve opens and allows air to move in one direction and blocks the the ...
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1 vote
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Helicopter hover flight question

I'm an avionics technician and I work on helicopters. This week I was trying to explain where comes the lift force to some friends. I'm a self-learner but I have a poor physics school background. I ...
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Why does air not flow backwards in Jet Engines in the combustion chamber? [duplicate]

In jet engines air is taken in, compressed and then fuel is injected and then ignited forcing the turbine to spin powering the compressor. What I am curious about is why the combusted air isn't forced ...
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Direction of acceleration of a helicopter?

Is the direction of acceleration of a helicopter always perpendicular on the rotor plane because while I was solving a polar coordinates dynamics problem nothing about the acceleration of the ...
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Are drag and lift forces directly proportional to air density?

I'm trying to work out how air density changes displacement during takeoff and up to a height of 35ft. All the websites I find say that the coefficients of lift/drag are Yet I want to know whether I ...
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How and where does air that is displaced by a constant moving vehicle flow?

How does air that is displaced by a constant moving car move? When a car is driving with constant speed, there is air displaced in front of the car. Let's say the surface of the car view flat from ...
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Why does Hoberman sphere open when thrown up? [closed]

Please try and explain this to a dummy :) I haven’t had any university level physics education, at least yet. I was messing around with a mega sphere (Hoberman sphere toy) at a family dinner when I ...
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How do I quantify an adhesive's ability to stick in contrast to flow?

Let's say you glue a ball to a shovel. How do you quantify this adhesive's and ball's ability to stick to the shovel, moving at different speeds, in air and then while the shovel digs into the ground? ...
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Is there such a thing as viscous vapor?

I'd like to simulate a scenario where a character suddenly encounters very high air resistance due to volatile vapors that spread and stick around. Is it possible for some type of gas to be viscous in ...
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Can a bullet return to the starting point (like a boomerang) assuming it is horizontally fired?

Consider a bullet having special aerodynamic shape was fired with a speed of 800 m/s. Is it possible for a bullet to come to the point where it is fired due to its aerodynamic shape. It is assumed ...
1 vote
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Can a bullet come to the starting point assuming it is horizontally fired? [closed]

Consider a bullet having special aerodynamic shape was fired with a speed of 800 m/s. Is it possible for a bullet to come to the point where it is fired due to its aerodynamic shape. It is assumed ...
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Can you estimate vertical wind speed based upon temperature difference?

I have some data from an automatic weather station, with recordings of both $\rm 2\ m$ air temperature and $\rm 2\ m$ air pressure and also the surface temperature. Is it possible to estimate vertical ...
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I'm having trouble solving the following problem. I've designed a control system for a quadcopter, my design is built upon a nonlinear model in the affine form: $$\dot{x}=f(x)+g(x)u$$ The system ...
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Why spinning bullet is more stable in air?

I found out about stagnation point recently, it is an arbitrary edge or point where the stream of air molecules parts. I was wondering could a spinning bullet affects the stagnation point to improve ...
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What is the optimum Teardrop ratio for Lowest Drag?

Ok, it's well known the teardrop shape provides the least air resistance, minimising drag (note subsonic speeds). But nowhere that I can find is a clear answer of what ratios would provide the most ...
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Variations in using the General Thrust Equation for a Jet Engine, which to use when?

I've been studying The General Thrust Equation form J. Anderson. The author left the subject at T=(m_air + m_fuel)V_e-m_airV_infinity+A_e(P_e-P_infinity) But while illustrating solved examples he ...
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What is causing the cups to lift up?

I came across this video on Reddit, and as you can see the guy is spinning one cup by putting it into another, and then blowing on it, and the cups lift up. Some are saying its Magnus effect, that it ...
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Different Densities in the equation of Continuity, how?

I'm studying the equation of Continuity from the book Intro to Flight by J. Anderson and there it mentions that $$\rho_1A_1V_1 = \rho_2A_2V_2$$ If the fluid is assumed to me ideal why does the formula ...
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The formula of the thrust force of Hoop Glider

What is formula of the thrust force of Hoop Glider (see image below)? I need to know: how does the formula depend on the length of the airframe, the radii of the rings and their width? For example: ...
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Aligning air flowing out from compressor with diffuser

I am currently designing small scale turbo jet engine and I have 1 problem regarding design. How to predict the angle of diffuser ducts for given compressor geometry and rpm? I am attaching the ...
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Is there an ideal shape for minimizing each type of drag at subsonic, transonic, and supersonic speeds?

The Sears-Haack body minimizes theoretical wave drag in supersonic flow on a body of a given length and volume. Are there shapes that minimize wave drag, viscous drag, turbulent drag, and pressure ...
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What happens to the distribution of the induced angle of attack, if we suppose the circulation distribution is constant?

Assuming the lifting-line theory, we know the circulation must go to zero at the tips of the wing. Therefore, I wonder if we can actually conceive such an idea as a constant circulation across the ...
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Origin of the thrust force in jet engine

I am reading a lot about the jet engine operation and I meet mostly explenation that the thrust is generated thanks to the exhaust nozzle that "accelerates" the air. However the nozzle ...
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Calculating soar uplift

As I understand it via https://en.wikipedia.org/wiki/Lift_(soaring)#Thermals some birds and gliders use warm columns of air to provide lift and stay aloft without an onboard engine. I would like to ...
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Why is there an "unsinkable disk" phenomenon? Is it related to the lift of the aircraft?

A metal disk with a hole at its centre sinks in a container filled with water. When a vertical water jet hits the centre of the disc, it may float on the water surface. Explain this phenomenon and ...
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1 vote
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Why cant there be a sonic velocity inside the convergent part of a nozzle? (ie upstream of the throat)

A convergent-divergent nozzle is typically used for accelerating or decelerating airflow to or from supersonic speeds. The typical configuration for such a nozzle is the de Laval nozzle that is ...
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Why don't bullets used in guns have sharp corner edges? [closed]

Why don't bullets used in guns have sharp corner edges? Like why are they spherical or smooth at the tip? Is it to avoid air resistance? But as my sir told that how speed we move proportional we get ...
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Pitot tube airflow speed measurement

how pitot tube can specify the airflow at aircrafts. according to formula airflow speed is related with fluid density. when aircraft passes through clouds it meets different density of fluid than ...
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Can astronauts fly like birds in the space station?

Can astronauts fly like birds in the space station? The space station is microgravity, and astronauts can't walk. Can we design a pair of wings for astronauts to fly in the space station? What if the ...
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Slipstreaming - is there a penalty?

When a following vehicle slipstreams close to a vehicle in front, by placing itself in a region of air moving at a similar velocity to the front vehicle, it is afforded a benefit, e.g. improved fuel ...
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How exactly does a fixed pitch wind turbine start from standstill/stall?

I might have a crucial gap in my understanding of the aerodynamics of a wind turbine but I am struggling to get my head around how a fixed pitch wind turbine can start spinning from a standstill? I ...
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Why does a crumpled paper fall down faster than a flat paper? [duplicate]

It can't be because of less surface area as we know that friction is independent of the surface area
1 vote
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Aerodynamic Problem in regards to a ping pong ball and and an open hole tube

I have a ping pong levitation system with a ping pong ball in a tube being pushed by a dc motor fan (shown below) and I'd like to define a relation of the balls height with the air velocity or airflow....
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Why d'Alembert's paradox has zero drag?

Why d'Alembert's paradox has zero drag? Even if viscosity is zero why drag is zero if there is no stagnation pressure at the back (right) side of ball? Why flow stay attached to ball surface,even ...
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Can the UAV fly in the space station? Can birds also fly in the space station?

Can the UAV fly in the space station? Can birds also fly in the space station? Birds can bump around the space station.
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Treatment of the Damping term in pendulum equation [closed]

I am confronted by two differing equations for a damped pendulum. I want to back out the drag coefficient at each point of a pendulum's motion. I have the velocity and the acceleration at each point. ...
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How to calculate the wind load force value and direction for the round cylinder tilted downwind?

I tried to look in internet but I mostly find the wind load on flat surfaces and square cylinders. In fact I need to determine the angle of the helium filled round cylinder attached to the ground so I ...
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Predicting drag or drag coefficient?

Would it be possible to mathematically predict what the drag on free-falling object will be in 10 seconds (for example), if you know the current altitude, velocity and pressure? I know you can ...
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What is the physics principle behind Helicone (wood toy)?

There is kind of toy "Helicone" (https://www.youtube.com/watch?v=nkmBLPHGp0E), It is composited with one base, one axle and many co-axle leaf-pairs. When rotating it in a direction and ...
1 vote
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Do heavier cyclists experience relatively less wind resistance?

I am a cyclist with no physics training (beyond high school). In general, lighter cyclists with high power-to-weight ratios are the fastest, but I am wondering if there is an advantage to being ...
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How does Venturi effect work in this case?

I'm not a physicist or a student. I just wanted to understand how the Venturi effect works in this case. I understand that the Venturi effect says that when a fluid flows through a constricted area, ...
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Flight distance of light bullet vs heavy bullet

The Problem We have argued with the brother, whether the heavier of lighter bullet will fly further. Intuitively, the lighter bullet has more velocity $v$ and can cover more distance before it falls ...