# 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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### Magnus effect without windspeed

Canagnus effect take place if windspeed is 0 ? Lets assume that our frame of reference a place an earth (e.g. soccer pitch) .We measure the windspeed and we find it zero.But if we make a knuckleshoot ...
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### Is lift force proportional to size?

I'm trying to calculate lift force of a particular object I'm working with. However, I can't find much information on how much force is required for an object to stay in flight though. My questions ...
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### Principle of Lifting of an Aircraft [duplicate]

While using the Bernoulli's equation to deduce the upthrust on an aircraft , a statement is always made that The air particles going above th wing have to cover a greater distance in same time than ...
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### Would it generate a lift if wind is circulating inside a nearly closed tube?

For a setup like the below image, would there be a lift generated to the tube, due to bernoulli effect?
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### Angle of Attack of a propeller blade

What will be the best angle of Attack for a propeller blade that is in the airfoil shape?
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### Propeller blades flat vs wing shape

Does a propeller blade with the shape of a wing produce more lift than a flat blade and will a blade with a wing shape produce lift in a ducted fan situation?
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### Why does the increase in velocity result in decrease in pressure in a flow? Are there any explanations behind?

So I have been searching for this answer that why would increase in velocity result in pressure drop and found no explanation, please help, thanks!
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### How fast do the aerodynamic forces on a surface build up?

I`m currently working on my thesis in the field of active car aerodynamics. In order to design a controller to move parts of the cars body I need to know how fast the drag and downforce acting on this ...
451 views

### Pressure distribution around an aerofoil

Some notes that I'm reading right now show a picture of the distribution of pressure around an aerofoil with zero angle of attack. The notes say that the pressure is identical at the top/bottom ...
225 views

### What's the equation for a streamlined body? [closed]

I'm interested in doing some simulations with aerodynamics, but I don't know what kind of curve a streamlined body actually is. Is there any kind of Cartesian formula for it?
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### Aerodynamics of cycling into a tail wind

I was looking at Steve Gribble's Cycling Calculator , and I noticed that the aero resistance was higher going 40 mph with a 20 mph tail wind than going 20 mph with no tail wind. Why is this? I always ...
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### Lateral Force on a Fin

I am wondering what the lateral force is on the fin of, say, an arrow, (or other befinned missile) as a function of the angle through which it is turned ... or more particularly what it's dependence ...
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### Motion of a contrail āvortexā

I want to understand what causes this motion on contrails (Cirricular motion) and itās name if possible. What effects it? How and why is it formed?
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### Shock waves at $M = 1$ and $M > 1$

When a wave moves faster than the local speed of sound ($c_s$) in a fluid, there is a shock wave since the fluid is unable to respond to the moving wave. Even if velocity ($v$) is constant, if ...
331 views

### How do you explain the formation of shockwave on the wing surface during near sonic flight?

Explanations of shockwave for the common folks (youtube videos, googling) all tend to focus on successive sound waves generated by the air craft traveling outward in circles (sphere). That to me, ...
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### Unconventional Propeller Efficiency

I am very inexperienced in propellers and fluid dynamics, but I have been experimenting with propellers. I messed around with propellers between 2 and 12 blades; theoretically, its obvious that the ...
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### Effect of Bodyform on Air Resistance [duplicate]

Visualize those little pictures as the front of vehicles like airplanes and trains. I wonder if I am right about my speculation below, and if so, if somebody could explain the exact reason. Sources ...
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### How does gravity effect to aircraft in sky?

Aside aerodynamics and buoyancy, Is there a simple way to explain how gravity is negligible in flight paths using free falling body diagram? In a parabolic trajectory,we know that at max height, ...
44 views

### Does aerodynamic heatings at the wall depend on the material of the wall itself?

I am reading "Fundamentals of Aerodynamics" 5th edition, J.D.Anderson. He said: "The slope of the temperature profile at the wall is very important; it dictates the aerodynamic heating to or from ...
112 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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### Density of ionised air

Is ionised air less dense than ordinary air, if so, by how much?
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### Parameters of the ground effect

I'm trying to build a large, rotary-wing Ground Effect Vehicle. In order to calculate the necessary size of my props and motors, I need to know how much additional lift the ground effect will provide ...
266 views

### Is it possible to knock over a bowling pin without hitting it?

I bowl professionally and there is a saying when you barely hit a pin and it barely falls over. People say that you "hit it with the wind." I've been thinking, is it actually possible to knock over a ...
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### Why does Anderson ignore a derivative of a normal viscous stress?

I am reading "Fundamentals of Aerodynamics" 5th edition, J.D.Anderson. In part 15.6, he said: Consider a steady two-dimensional, viscous, compressible flow. The x-momentum equation for such a ...
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### Questions about shapes and the reason behind the drag coefficient differences

What is the reason that a streamlined body has a drag coefficient that is lesser than the drag coefficient of a streamlined half-body, when the latter has a completely flat bottom, while the former ...
300 views

### How significant is the material in drag force calculations?

I went to Wolfram's "Drag Force Calculator" and received 4900 newtons for a cone that has a radius of 3 meters and a height of 3 meters, moving through air at a standard pressure, 15 celsius, at a ...
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### 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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### Units caculation in the article don't match for reynolds numbers higher than 1

The article discusses the forces acting on a falling object in respect to the drag forces and reynolds numbers. The article suggests for varying Reynolds numbers, the force of drag equation is written ...
541 views

### Supersonic wind tunnel with total pressure loss?

I am reading "I am reading "Fundamentals of Aerodynamics" 5th edition, J.D.Anderson. If you have the book, go to chapter 10: Compressible Flow through Nozzles, Diffusers, and Wind Tunnels". In order ...
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### Moving a marble in a maze using wind force

For a school assignment, I have to write a game where you can move a ball through a maze by generating unidirectional wind when the mouse is clicked. The ball is on a flat surface. The concept is ...
642 views

### 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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### Air resistance - smooth vs pimples vs dimples

Is there any difference in behaviour between a smooth surface, surface with dimples (dips) and surface with pimples (bumps) when considering aerodynamic drag in a non-rotating frame? I have a flat ...
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### Is there a conventional term for the phenomena of when fluids increase in speed after hitting the ground?

Prompted by this question here that was near the top of the recent physics questions, Does airflow also increase in velocity as it hits a surface as fluid does?, I simply wanted to ask about the term ...
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### Does airflow also increase in velocity as it hits a surface as fluid does?

When you drop a stream of water to the ground, you can see it spreading out over a large area at a higher speed than it fell as the water thins out against the surface. Air is like fluid in many ways, ...
547 views

### What is the physics behind the movement of the split-finger fastball in baseball?

A split-finger fastball, or a splitter, is a baseball pitch thrown like a fastball with an v-shaped split finger grip. When thrown correctly, it moves like a fastball, straight in the air, but ...
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### How does the radius of a pipe correlate to the velocity of air at a gradient of sizes?

Suppose your pipe isn't a mere cylinder, but is more like a cone or a solid revolution of an ogive curve. It's standard that a small pipe will force air through it faster, but how do you calculate the ...
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### Why papers move instantaneously upwards as they fall? [closed]

Sometime papers or leaves of trees seem to move a bit upwards as they fall. Why is that so?
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### Why do most centrifugal fans found in laptops have tiny blades? [closed]

If you were to use a centrifugal axial fan instead, won't you be able to achieve higher flow rates and better pressures? It seems like the efficiency of these motors are very low.
70 views

### Can electrostatic forces be used to shape aerodynamic response of a body?

Let suppose the following body: blue is electrically charged positively, red is electrically charged negatively, yellow is an insulator. I would like to understand the effect of the ...
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### Do blades on the same rotor really move at different speeds?

I was browsing Stack (great way to kill time at work) and I came across this question. One of the comments confuses me somewhat. @Zlelik No, helicopter blades cannot exceed the speed of sound - ...
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### Is the terminal velocity in air independent of the direction of the movement?

For example, a body in free fall on earth and the same body experiencing the same acceleration ($g$ in this case) but horizontally, would have the same terminal velocity? (considering that the ...
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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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### Aerodynamics equation

I still need to find an equation for the following restated problem: Suppose a full-size glider passes 10 feet over my head at high speed. No doubt I will feel the downward air pressure caused by the ...
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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 ...
402 views

### How can I derive the stress tensor for a Newtonian fluid in more physical terms?

The question is quite fundamental and more on a beginner's level (not sure if good in this high-level-forum, but I try): I have big problems in understanding the stress tensor for Newtonian fluids in ...
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### Terminal velocity equation for falling skydiver doesn't work for empirically determined values

Try as I might, using the terminal velocity equation with empirically-determined $v_{T}$ and $C_{d}$ requires a skydiver to have a very small projected surface area. I'm not sure what I am doing ...
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### Downforce of a F1 car? [closed]

According to Wikipedia a Formula 1 car produces downforce equal to it's weight at around 130kmh. At 190kmh it produces twice as much downforce. To my understanding of Physics double the air velocity ...
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### Aerodynamics of wet versus dry sail

I recently read in a history book that sailing ships that really needed to go fast would pour water on their sails because "wet sails capture the wind better than dry sails." Why might this be? Does ...
533 views

### How does the lift force of an airplane work? [duplicate]

At first I thought that the lift force of an airplane wing came from the buoyant force of the air. Thus we can calculate it's lift force using $$F_b={\rho}gV$$ However, that does not seem to be ...