A subset of [tag:fluid-dynamics] 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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144 views

Helicopter, Tricopter, Quadccopter - what's really happening here? Are there generalized advantages on a small scale?

There have been, it seems, a proliferation of quad-copters commercially available. Amazon seriously tried to use them for deliveries. (Search Drone on their website.) The NFL uses one for cameras. ...
3
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1answer
169 views

Is this xkcd comic feasible? [closed]

I was reading through some xkcd comics, and I came across this one (http://xkcd.com/620/). In the comic, one of the main characters harnesses 91% his weight in order to be able to 'fly' with the lift ...
0
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1answer
70 views

What are the preferred height and diameter proportions for a rocket model?

I'm pretty sure, that if you make a rocket that's relatively small in height compared to diameter, it will most likely not fly very high and probably spin out of control. What about a rocket that is ...
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0answers
36 views

How much does grabbing a piece of a plane free falling change your survivial?

Just for context let's saying you are falling from a plane in free fall position at 56m/s(200 km/h or 120 mph) and you grab onto a wing which slows you down to 25m/s. You weigh 70kg. so ...
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2answers
46 views

What are the major differences in group-skydiving as opposed to “single” skydiving?

Surface area/the cross-sectional area is greatly increased, so my thinking is it should decrease terminal velocity as well as a couple of other factors. But mass changes too (since there would be more ...
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2answers
207 views

Boomerang physics and aerodynamics

I posted a question before on this website asking how to build a boomerang for a project which can fly at least 200 feet, so how would I increase the flight path. A user responded with: slow down the ...
1
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1answer
105 views

Thought Experiment: spinning ping-pong ball on International Space Station. What would Happen?

A ping-pong ball with a certain vector and rotation/spin in zero G, 1 atmosphere. If you did this experiment in a space station would the ball 'orbit in a circular fashion. or "Can you throw a ...
0
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1answer
43 views

Is there a way to convert CFM (rate of air moved) to kilograms of lift generated?

Is there a way to convert CFM as in a rate of volume of air moved to kilograms of lift generated?
1
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1answer
157 views

Boomerang torque and angular momentum

I'm building a boomerang for a project, but I've made it a goal for myself to have a boomerang which can fly at lest 200 feet, so how would I increase the flight path. Angular momentum increases in ...
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0answers
64 views

Books on experimental methods, fluid mechanics related

I need some good books on experimental methods, requirements are: Fluid mechanics related; Thermal, multi-phase etc. topics should be covered; Traditional methods are good, but it would be greater ...
0
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2answers
141 views

Why can't we fly? [closed]

Why can't we fly? It contradicts with our known laws of physics, but which one? Is it possible that once we know gravity better we would be able to fly using some sort of anti-gravity machines like ...
0
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1answer
75 views

When an aircraft flies over, glass window vibrates…Infrasound?

When an aircraft flies over, my big glass window vibrates, making a ticktack beating. Its frequency sounds low, less than 10 beats per second actually. I'm wondering about the mechanism of this ...
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0answers
45 views

Why are flight feathers asymmetric?

I've always heard that flight feathers were asymmetric because the shape generates lift, like an airplane wing airfoil shape. But, the feathers are not oriented with the shaft perpendicular to the ...
2
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5answers
91 views

Is more lift always better?

In the domain of aircraft, and more specifically powered flight, is there any case in which you wouldn't want the airfoil used to generate as much lift (and as little drag) as possible at a null angle ...
3
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2answers
118 views

Does drag produce heat?

When a solid object moves through a fluid drag is produced. Does this drag produce heat? I believe drag should produce heat as it is the friction between fluid and surface of object. Is this true or ...
2
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0answers
51 views

Would Superman's flight be damaging? [closed]

I recently asked this question on the effects of Superman's sonic booms and it's become clear that Physics.SE is better equipped to answer it. I'll set up some assumptions. Superman's travelling to ...
2
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1answer
70 views

Measuring small amounts of lift in a wind tunnel

I am doing a science project on how paper airplanes generate lift, and I need to know how to measure the amount of lift generated by the plane.
3
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1answer
572 views

Why do vapour cones form around jet fighters?

Apparently this phenomenon has nothing to do with jets breaking the sound barrier and has something to do with the Prandtl-Glauert singularity as described on Wikipedia. But, the Wikipedia article ...
3
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1answer
611 views

what kind of wings would a person need to fly?

I heard from a teacher in school that in order to fly, he would need a wingspan much wider than the wood shop where he was standing. Thinking back on it, I assume the number of times you can beat your ...
5
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3answers
2k views

Benefits of rear spoiler in cars

What would be the benefits of rear spoilers in cars, like this one:
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0answers
32 views

If i had a aero-nautical object [closed]

If i had a aero-nautical object with a span of 10 feet and a weight of 40 pounds with a strong gale blowing do you think i could make it off a cliff with out plummeting to total utter death?
1
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1answer
47 views

Delta wing flow patterns (straight and yawing)

I was wondering the differences between fluid patterns and their consequences when a delta wing is straight and yawed slightly.
-3
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1answer
107 views

What causes a spacecraft entering the atmosphere to catch fire? [closed]

What causes a spacecraft entering the atmosphere to catch fire? A) surface tension of air B) viscosity of air C) high temperature of upper atmosphere D) greater proportion of ...
5
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2answers
529 views

How does train back draft work

Quoting platforms and stations : Fast trains can create a vacuum called a ‘back draft’ that can blow you over or suck you under a train. How does that work ? I thought that the volume of air ...
2
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1answer
68 views

How to design windy area - what variables?

When you're walking around malls or parking structures, or a building corner, you'll sometimes notice areas with consistent windiness. I was wondering what positions, angles, wind direction, ...
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3answers
482 views

Propellers and the Speed of sound

I was reading this website that described a novel wind turbine technology and it has this quote: In the mid-20th century, open propeller-driven planes with piston engines reached performance ...
6
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1answer
2k views

What is a Physically Accurate Explanation for the Kutta Condition?

Countless arguments between highly intelligent people have been waged (on this very site in fact) as to exactly how lift can be explained in an experimentally and mathematically rigorous way. Taking ...
0
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1answer
622 views

How a fan moves air? [duplicate]

How does a fan moves air towards you (I mean in 1 direction). Also propeller and fan have different shapes, does it mean they work different?
35
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3answers
3k views

What is going on in front of and behind a fan?

Why is it that when you drop paper behind a fan, it drops, and is not blown/sucked into the fan, whereas if you drop paper in front of a fan, it is blown away?
7
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1answer
168 views

Why Are Normal Shock Waves Unstable in a Converging Channel?

While learning about shock waves in an introductory Gas Dynamics course, it was revealed that normal shocks are unstable if formed in a converging channel. Even if the local conditions ostensibly ...
5
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2answers
202 views

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 ...
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0answers
92 views

Static,total and velocity pressure at a point

I have a past exam question that I am stuck on. $200$m$^3/s$ of air is entering a shaft of $5m$ diameter, the density is $1.18$kg/m$^3$, and I have shock loss of factor $X=.5$ I want static, ...
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1answer
104 views

Is the flow in a ducted fan really incompressible?

I have a long duct with a fan in the middle of it. The fan causes a steady airflow in the pipe which is at low speeds (incompressible) the mean flow in the pipe is about 10 m/s. However the fan blades ...
2
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1answer
4k views

Calculate flow rate of air through a pressurized hole

I was wondering about this: If there is a pressurized container, like a tank of compressed air at some pressure that is greater than the ambient air pressure, and this tank of air has a hole in it, ...
1
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1answer
129 views

What does centre of lift depend on?

I've read in many places that centre of lift is about quarter chord of the wing and that post-stall lift (the part developed on lower surface) has centre midchord. The later makes sense; the pressure ...
4
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1answer
256 views

Integrating pressure over a surface

Consider the 2D airfoil below. In engineering (and maybe physics) you will often see something like the following as an expression for the pressure force acting on a surface (in this case a curve ...
2
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2answers
142 views

Confused about the theoretical origin of quadratic air drag [duplicate]

Though the mathematical concepts underlying quadratic air drag are quite straightforward (a single variable differential, just like the linear drag equation), my text book (and online text books) ...
2
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1answer
347 views

How to calculate the drag coefficient using terminal velocity?

I was wondering if it were possible to calculate the drag coefficient by allowing an object to reach terminal velocity. Can you rearrange the terminal velocity formula to give the drag coefficient?
8
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2answers
2k views

How much more efficient is a road bike than a mountain bike? [closed]

What would be a good estimate on the difference of efficiency between a road bike and a mountain bike? A number of links cite all the usual reasons: thinner tires, better aerodynamics... But I'm ...
3
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1answer
61 views

Why does a piece of paper travels up when inserted into a kite's thread?

When I was young, I would insert a piece of paper into a kite's thread. The paper would travel upward till it reaches the head of that kite. What makes it to go up against the gravity even if the ...
8
votes
1answer
262 views

Could the phenomenon of vortex bursting be exploited to reduce wake turbulence?

One of the classic stories in the annals of aerospace engineering is the development (and subsequent redesign) of the F-18 and its Leading Edge Extensions (LEX) due to fatigue problems, problems that ...
9
votes
2answers
883 views

Why do co-rotating vortices coalesce, but not counter-rotating ones?

In studying the aerodynamics of modern aircraft equipped with high-lift devices, I have discovered that quite a number of distinct trailing vortices are present in the immediate wake of an airplane in ...
7
votes
2answers
257 views

How should I throttle my rocket to reach highest altitude? [closed]

"Real world" problem. Suppose we want to launch a rocket equipped with an engine which can be throttled as we prefer. Suppose also that the amount of fuel burnt per time is directly proportional ...
1
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1answer
243 views

Why are the backs of airplanes curved?

I get the front part, but why is the back curved too? I do not see a problem with the back being flat.
28
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13answers
2k views

What does a wing do that an engine can't?

This isn't a question of how a wing works -- vortex flow, Bernoulli's principle, all of that jazz. Instead, it's a question of why we need a wing at all. A wing produces lift, but why is that ...
0
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3answers
102 views

How laminar or turbulent is air?

Consider an outdoors scenario, with good weather and no sensible air currents at the floor level. How turbulent or laminar is the air surrounding this environment?
1
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1answer
188 views

How much wind does it take to tip a sign over? [closed]

Or said another way - how much counterweight does the base of a sign need to keep it from tipping over given a specific max wind? Assume the sign does not let wind through Assume the base of the ...
2
votes
2answers
87 views

Maximum helicopter height [duplicate]

Helicopters or dual/quadcopters stop rising after reaching some height from the ground. What causes that? And what one should do if he want to prevent this, if he want the helicopter to keep rising ...
4
votes
2answers
74 views

Are Mach Diamonds radially symmetrical?

Videos like this show a form that suggests a radial symmetry in the gas jet. The same is reinforced by schematic illustrations. But other images, like this, look like there is a twisting structure ...
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4answers
1k views

Experiment - Measuring final velocity of a parachute

I'm working on a project that involves a scale parachute. It is vital for the project to get a good measurement of the speed it has when it lands. We still haven't built the parachute, but we need a ...