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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Is the total pressure coefficient always 1 in incompressible flow?

I have to do some calculations to get the drag from an experiment with a wake rake. In the equation I have to enter the total pressure coefficient $C_{pt}$, but in my calculations it seems to always ...
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3answers
719 views

Effective angle of attack of a wing

Is the angle of attack of a rectangular wing influenced by the dihedral ($\Gamma$) of the wing? If e.g. a wing exists with $\Gamma$ = 0$^{o}$ it has angle of attack $\alpha$. If the dihedral is set ...
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1answer
145 views

Aircraft nose-up glide

In the pilot's introductory book "Stick and Rudder" it claims that a nose-up glide is possible. It doesn't state how, why or when. It implies it's possible to do and maintain a constant forward ...
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1answer
740 views

How fast does water fall in the middle of a very very thick waterfall?

Let me create a very artificial experimental set up. Take a bathtub the size of Delaware and suspend it a mile above the ground. Fill it with water (though I'm not sure to what depth - and it might ...
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334 views

Forces on an aircraft - thrust, lift, drag, weight

I'm extremely sceptical about the wikipedia page on aircraft flight mechanics. When describing 'straight climbing flight', it says: lift is unable to alter the aircraft's potential energy or ...
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4k views

Position of aerofoil force moment, center of pressure, aerodynamic center

I'm confused by wikipedia's page on aerofoils, the aerodynamic center, and center of pressure; it seems to contradict itself. The airofoils page says the center of pressure is at the same position as ...
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1answer
401 views

Propeller modelling

I need a (very) approximate model of a propeller on an aircraft. My principal question is this: what would the relationship be between: Propeller rate of rotation Aircraft speed Force generated by ...
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1answer
3k views

Air Turbulence and DIY laminar flow hoods

So for years on the mycology, plant tissue culture, and DIY laboratory websites there has been this ongoing debate on how to achieve laminar flow in a home built laminar flow hood. Flow hood link! ...
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288 views

How should holes in a Tesla turbine look like?

I think of building a Tesla turbine out of old hard drives. Now I wonder how to cut ventilation holes in the platters. On the internet there are a lot of different attempts on that matter. A lot of ...
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4k views

What causes an aircraft to roll when rudder is applied

When continuous rudder is applied in a typical light aircraft during straight and level flight at "normal" flying speeds and altitudes, the primary effect is that the aircraft will yaw to the left - ...
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820 views

Do modern Formula One cars produce enough down-force to drive upside-down?

For example, if they were driving at top speed through a long tunnel, could they transition to and stay on the ceiling?
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164 views

Estimating drag due to wind - ribbon-shaped sail

In the countless calculations and discussions concerning the "space rope" I've never found any addressing its capability to resist winds. Consider, as in most current works, it's a 1m wide ribbon, ...
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2answers
129 views

Disconnected aileron/surface deflection in terms of speed?

Would a disconnected surface, especially aileron, deflect upwards as you slow down due to increased alpha? I figure out it is more likely to deflect upwards as you increase your airspeed, thus having ...
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165 views

Control cable failure and critical flutter speed margin?

I'm a private pilot, and I have some questions to those who have knowledge of the aeroelastic effects and flutter phenomenon. I would like to talk a little about aerodynamic flutter onset speed and ...
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1answer
368 views

Limitations of drag equation

The magnitude of the air resistance for objects with Reynolds numbers greater than 1000 is given by the formula: Why it does not hold for objects with lower Reynolds numbers? Can I use this ...
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2answers
1k views

Why do cars gain lift while going at a high speed?

I've been researching the physics involved with spoilers and I've just been turning up the same information about spoilers giving the back wheels of a car more traction by acting as an up side down ...
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499 views

Energy from man-made tornadoes

Peter Thiel just paid $300,000 to Canadian inventor Louis Michaud who is working to construct useful "man-made tornadoes" or "atmospheric vortex engines" which could be components of future power ...
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1answer
136 views

Stability of balanced masses with different surface areas

Say I have this setup. The two round objects have equal mass and their centers of gravity at the same distance from the shaft. The objects only differ in that they have different surface areas ...
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3answers
3k views

Does a wing in a potential flow have lift?

I have a hard time understanding whether or not a wing placed in a potential flow, assuming there is no viscosity and no friction with the wing, will produce a lift. I've seen several contradictory ...
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1answer
193 views

What velocity must an aircraft achieve for its shock wave to transform to plasma?

A follow-up to After what speed air friction starts to heat up an object? I understand there may be technological limitations at present ... but, is it theoretically possible for a body to travel ...
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1answer
1k views

Turning an airplane - coordinated turn and inclinometer (“the ball”)

I'm flying, turning in a stable orbit, i.e. at constant level with a constant angle of bank, at constant airspeed, with a constant radius of turn, as in the picture here (sorry it's my first post, ...
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2answers
464 views

What alternative shapes may a rocket heading into orbit have?

It looks like most rockets that head out of Earth, or even into orbit are pencil shaped (or nearly so). I would take this to mean there is some mass of air such vehicles push out of their way. What ...
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2answers
94 views

Can additional airfoil enable a commercial liner to reach 100km altitude?

Assuming that it's engines are incapable of dying out at 100km altitude, would mere addition of airfoil area enable a commercial liner e.g. B787 to reach that altitude?
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410 views

Finding an equation relating the mass of a blade of a wind turbine to its velocity

I'm writing up my physics coursework and I thought I'd try and find an equation described in the title. This is my attempt: Is it correct?
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5answers
774 views

Is flying really easier on smaller scales?

In the book Playing with Planets, the author makes the following argument, pertinent to flying robots of the future: As it is, an important law of physics says that smaller organisms fly much more ...
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1answer
4k views

Did Felix Baumgartner produce a sonic boom during his jump?

I really got to thinking about this. The speed of sound is measured at 761.2 MPH at sea level. But how does this number change as air density decreases? The lack of air density is what allowed his ...
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2answers
219 views

Supermarket refrigerator - why is it noticebable colder in this shop area?

As we know fridge can't cool room in which it is (according to Second Law of Thermodynamics, heat emitted by fridge is greater than heat absorped). However, when we go next to the fridge in ...
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426 views

propeller flying physics for the layman

I'm starting a (quad?)copter build, and i can find plenty of knowledge about stabilizing the craft and things related to gyroscopy. but there's absolutely zero information on things that help me ...
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4answers
396 views

Bicycle Wheel Drag in Slipstream

I was recently driving behind a car that had a bicycle mounted on a carrier over the rear bumper. The bicycle wheels were not bound so they were rotating in the slip-stream of the car. I wonder, the ...
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1answer
261 views

Parachute jumping (high altitude)

I heard about parachute jumping at an initial altitude of 30km. I want to simulate this flight numerically. How could I simulate the air drag (I mean, Which equation gives the air drag)? Normally I ...
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2answers
598 views

What would be an appropiate shape for a parachute?

I'm trying to design a parachute that minimizes the descent velocity, but I'm not sure what shape I should use. From what I've read, ellipse-shaped parachutes are too aerodynamic and minimize drag, ...
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0answers
240 views

What happens to a delta-wing plane when it's nose is tilted away from the line of motion 30 to 45 degrees horizontally?

Consider a delta-wing plane whose wing spread angle is 61 degrees (the plane looks like a flying equilateral triangle). What would happen if a cross-wind hits it, so that the direction of motion ...
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2answers
210 views

Inefficiency Comparison of Car Air Conditioning vs. Open Windows

On a recent long, hot journey in Spain, I was pondering which was the most efficient way of cooling the car. Which of these would be the most effective? Switching on the air conditioning, thereby ...
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3answers
350 views

Why is an Aircraft Runway NOT like a Teaspoon?

If the aircraft runway were like a teaspoon (by this I mean, flat in the beginning, then curving downwards and finally upwards), would it not work in favor of the propulsion of the aircraft? In spite ...
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2answers
6k views

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 ...
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1answer
1k views

Paper plane between two fans - is this possible?

The setup: two fans facing each other, distance around 1m. Both are turned on. In between them, place a simple paper plane and according to this video, it will fly. ...
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4answers
319 views

What do spacecraft have in common with atmospheric aeroplanes?

Science fiction depicts spacecraft as both deep-space & surface capable. Is this feasible? I would have imagined a vessel constructed for space travel to have little in common with operating ...
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1answer
323 views

Why ballasted gliders fly faster

The fact: Gliders have ballast tanks that can be filled with water. The addition of ballast increases weight, and this allows the glider to fly at faster airspeeds while maintaining the same glide ...
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3answers
1k views

Why airplanes fly: the final truth

The questions about the reasons the aircraft fly are frequent among scientist, since the high school until now, even if I work on the other side of fluid mysterious world (the Low Reynolds numbers ...
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2answers
188 views

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 ...
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1answer
2k views

Difference between propeller and fan in pulling force

In the context of producing a pulling force perpendicular to the 'spinning plane' of a propeller/fan, is it correct to say that a propeller mainly achieves it's force by being aerofoils producing ...
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2answers
2k views

What is the optimal design for a paper airplane? (Or, at least, how can you approach it?)

Having only really known two designs for paper airplanes since my days as a child, one which flies about eight feet and another which flies about ten feet, I have always wondered how people manage to ...
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3answers
1k views

Does wind speed things up or accelerate things?

This question may seem odd, but I can't think of anything better. So I'll go straight to the point. Let's say there's a projectile in air going east, shot at a certain angle, with a certain speed. ...
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5answers
2k views

Turning an Airplane. What actually causes the circular motion in a banked (roll) turn?

Basically I'm wondering if this is correct. Which essentially says that you need a torque to get the nose of the craft to turn and that this is provided by the rear tail surfaces. After trying to ...
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4answers
1k views

Why is exhaling more forceful than inhaling?

By blowing at pencil, a piece of paper, or another object up to fifty centimeters away, I can cause it to move away from me significantly. But I can't move an object toward myself by inhaling sharply ...
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0answers
333 views

Why don't Turbojet engines use the De Laval Nozzle? [closed]

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 ...
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2answers
418 views

Forces on an airfoil

I'm building an airplane (Super Baby Great Lakes) and I'm wondering something about airfoils. In particular (this plane is fabric covered), I'm wondering about the lifting forces on the main wings. ...
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2answers
529 views

Why does the higher pressure of air underneath an aeroplane wing keep it flying?

With aeroplane flight, the wings are shaped so that the air that goes over the top of the wing has to travel faster than the air that goes below the wing. This means that the air below the wing has ...
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2answers
1k views

What do bullet trails really look like?

In the movie The Matrix, during "bullet time" sequences, bullets are shown trailing evenly-spaced refracting blobs: ...
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339 views

Laws of aerodynamics after breaking the sound barrier

my knowledge of physics is not very extensive, so I hope my question isn't too stupid. I know that when (for instance) a plane breaks trough the sound barrier, the laws of the aerodynamics change. ...