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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).

A subset of the 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).

914 questions
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Why does the air flow faster over the top of an airfoil?

I understand the common explanation of lift, which describes the airflow over the top of the wing as moving faster than the air below the wing. However, I don't quite understand why the air moves faster. I've read some explanations citing a…
Michael
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Why is paper (or any tailless) airplane pitch stable?

To clarify my question further I'll use a practical example. Here is the simplest paper plane design I could think of - it is a rectangular thick drawing paper with a weight attached at the middle of one of the long sides. I used a paper clip…
Cleric
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How do eagles fly slowly for a long time?

Eagles fly slowly for a long time. Many other species fly faster and move their wings faster. But eagles keep their wings steady, and move only their tail. How do they move slowly in the air, without falling down? Can this eagle flying technique…
Valarpirai
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Why is 55-60 MPH optimal for gas mileage of a passenger car?

My driver's education teacher back in high school said 55 MPH is optimal for gas mileage of a passenger car. Just last week, I read an article in a magazine saying 60 MPH is optimal. These numbers are pretty close, so there's some validity in the…
JoJo
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NASCAR drafting at Daytona

This year, the racetrack at Daytona has been repaved. The track was always faster than other tracks NASCAR raced at and several cars in a "train" were faster than single cars or smaller trains. This year is different, however, because two car…
user2119
9
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2 answers

Does it make sense to open one window all the way when the other window is much smaller?

I can't wrap my head around this idea because I don't know much about air flows. Say we have this imaginary apartment with two windows, one of which is two times smaller than the other: Will the first one let more air through than the second? Or is…
user1306322
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Number of blades in a fan

How does the number of blades in a fan affect the flux of air? I read that 3 blades are the best option but some companies uses more blades because there's a misconception among people that more blades generates more air.
user5402
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Why Don't Birds Stall?

I often hear about planes stalling when they lose lift due to low airspeed/too high angle of attack. Why don't birds stall? Does it have to do with the structure of their wings and their flexibility, or their higher power/weight ratios relative to…
Kupyn
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Aerodynamics of two objects closely following each other

On bicycles.se a question came up about whether one cyclist drafting another causes the lead cyclist to be slowed down. A contributor suggested that the opposite might be the case, that the leading cyclist would be 'helped' too. Clearly, in the real…
ʍǝɥʇɐɯ
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2 answers

Calculate quadrotor propeller torque due to aerodynamic drag

I'd like to know the right formula to calculate torque of a quadrotor propeller (propeller pitch is constant) due to aerodynamic drag in terms of angular velocity $ \omega $. For the sake of my simulation I'm assuming APC 10x4,7 propellers. I'd like…
mmm
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Does a larger camber produce more lift?

I'm doing an experiment using two airfoils of the same dimensions except for the camber. I am getting results in which more lift is produced using the smaller wing. Is this correct or are my results incorrect? Thanks
Gabriel Aaron
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2 answers

how does a helicopter get forward thrust?

Just passed a helicopter on my way to work. We have read in some detail how an airplane gets forward thrust and lift by deflecting air. How does a helicopter with horizontal fans achieve that ?
New Horizon
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How do propeller blades rotating through air accelerate it to provide thrust?

I have a good understanding of how a propeller works. An engine turns the blades resulting an increase in velocity. But how do the blades accelerate air to result in thrust?
Ethan
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Why does reentry from space tend to result in such great heat?

Let's pretend for a moment that the atmosphere had sea-level density, pressure, and temperature all the way up to, say 500km high, and then would abruptly end in a complete vaccum. In such a situation you could have a glider orbiting at 501km high…
GJ.
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Why don't Turbojet engines use the De Laval Nozzle?

Why don't Turbojet engines use the De Laval Nozzle? In fact, it seems that in a typical turbojet, the output nozzle contracts, not expands. As the temperature of exhaust gases is high -- it should be possible to extract more energy out of it in this…
BarsMonster
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