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).

learn more… | top users | synonyms

0
votes
3answers
39 views

Modelling an Airplane Question

For an assignment of mine I am creating a very basic model of an airplane, where I choose to consider a fixed amount of parameters that affect flight and to disregard others which I find too difficult ...
3
votes
2answers
473 views

Could a bladeless “Tesla Turbine” type air compressor be used as a high vacuum pump?

I have a wacky idea for a new vacuum pump, I'm trying to figure out why it shouldn't work. I'm interested in learning about Tesla Turbines, specifically when used in reverse as compressors or vacuum ...
1
vote
2answers
67 views

How is determined the shape of the wings of an airplane?

My understanding of the reason why a plane fly is summarized by the following figure: because the upper part of the wing is curved, the air above the wing has to flow faster than the wing below. This ...
1
vote
2answers
52 views

Roll angle for banked turn of an aircraft on a tilted plane

It is known that for a banked turn of an aircraft on a plane parallel to the ground, the roll angle $\Theta$ computes as $\Theta=\arctan(\frac{a}{g})$, with $a=\frac{v^2}{r}$ the centripetal ...
1
vote
2answers
66 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 ...
3
votes
1answer
66 views

Stagnant Air Deep Inside Vintage Mines

This is really a question more about mining ventilation than true "physics." I occasionally explore a southwest desert mine, but am aware of the hazards - typically passing over half a dozen vintage ...
2
votes
1answer
50 views

How does quadcopter's battery capacity relate to it's maximum flight time?

Suppose that we have a quadcopter weighing 3 kg (without a battery) and a battery (let it be Li-Ion type) weighing 2 kg. With this battery our quad can hover for 20 minutes until the battery runs flat....
1
vote
1answer
78 views

What is the difference between the Method of Characteristics being formulated in terms of theta & alpha and theta & nu?

So I'm doing an MSc thesis involving the method of characteristics in rocket nozzles. My lecture notes have the MoC formulated such that the positive characteristics are defined as: C+ = Tan ( $\...
1
vote
1answer
96 views

Does a ceiling fan sound louder when humidity is higher?

It seemed to me the ceiling fan is making louder noise(of cutting through the air) when the day is a bit damp/humid, especially after a rainy day/hour. Is this a valid observation? Can the increased ...
1
vote
1answer
87 views

Speed of pressurized gas escaping into vacuum

Does speed of pressurized gas escaping through a narrow nozzle into vacuum depend on the pressure? I've asked a question on Space.SE regarding utilizing gas at extreme pressures for propulsion. My ...
1
vote
1answer
214 views

Why golf balls travel faster if they spin?

From the book I have been given to read I found that balls spin due to the centripetal force but i am confused about how exactly do the resultant force causes it to spin and move forward about the ...
0
votes
1answer
31 views

Will a rocket accelerate faster if the air in front of it is sucked away?

Imagine a rocket with a super powerful vacuum pomp on top of it. These pomps or whatever should manipulate the airflow in front (or around) the rocket. What causes the rocket to accelerate quicker and ...
0
votes
1answer
29 views

How drag force relates to velocity in the air?

As you know in the formula of drag $$F=0.5 *d*A*C*v^2$$ in different velocities we have different Reynolds number. and the Reynolds number relates to coefficient of drag. my question is how can we ...
0
votes
1answer
118 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
votes
1answer
30 views

Explain an experiment: airstream between two hinged curved surfaces

Please, see the following video (the experiment starts at 3:40 and ends at 3:55): https://www.youtube.com/watch?v=7pB6q_bH35s&feature=youtu.be&t=216 The basic idea: given 2 curved surfaces ...
3
votes
0answers
118 views

Turbulence forming between the coaches of rail

is there any specific reason why rail coaches are connected by a rubber sheet; not of any other material ? I watched a documentary on trains (Discovery Channel) which said it connecting coaches by ...
3
votes
0answers
177 views

What kind of shape has the lowest flutter wind speed?

What kind of shape has the lowest flutter wind speed and is the most unstable? I mean for rigid body. Thanks Yes, I know many factors affect the flutter in a MSD system (for rigid body), however ...
2
votes
0answers
28 views

The torque produced in the rotor blades of an axial flow turbine

I want to ask about the torque experienced by a axial flow turbine, and how the torque is related to the ange of attack, or pitch angle of the turbine blades. (I'm new to technical terms, please ...
2
votes
0answers
322 views

Modal analysis with aerodynamic damping

I'm using modal decomposition to predict the steady state response of a beam structure to harmonic loading. The structure itself is very lightly damped, but we know from experiments that the ...
2
votes
0answers
371 views

What is wrong with this downforce calculcation?

I tried calculating the downforce of a spoiler I need for a robot. I used this formula. $$F = \frac{1}{2}Ac_a\rho v^2$$ Where $\rho$ is air density, $v$ is the speed of my robot, $c_a$ is the lift ...
2
votes
0answers
192 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 ...
2
votes
0answers
482 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 ...
1
vote
0answers
44 views

Plane landing into a tunnel

Typical action movies cliché is landing a plane in a tunnel or even a flight in a tunnel. Let's drop any doubts about supreme heroic piloting skills of the characters etc. and focus on aerodynamics. ...
1
vote
0answers
63 views

Calculate ballistics using Pejsa method (bullet physics)

I'm not sure if it was already asked, but, could someone please explain the Pejsa method of ballistics, specifically the velocity and trajectory (no energy, wind or lead etc.) (just drop drift and ...
1
vote
0answers
47 views

How is egg shaped ball different from a spherical ball, aerodynamically?

I don't know whether this is the right place to ask this question or not but, how is an egg shaped ball aerodynamically different that the spherical ball? What advantages could one have over the other?...
1
vote
0answers
118 views

How to calculate maximum wind speed in a funnel (Venturi Effect)?

It must be in an open area, so nothing forces the wind, just himself. Lets assume that the wind is blowing only one direction. I assume that at some point the speed will stop increasing and it will ...
1
vote
0answers
46 views

How big is the power loss of a downwind wind turbine due to turbulence created by an upwind turbine?

When a horizontal axis wind turbine is placed downwind of another horizontal axis wind turbine (distance between the two is minimal), then the downwind wind turbine has a lower power output because of ...
1
vote
0answers
96 views

Mass flow rate and force on moving disk

If I understood correctly, the force $F$ related to a given mass flow rate $\dot{m}$ through orifice area $A$ (or, say, on a disk of area $A$) is given by Newton's 2nd law of motion - assuming a ...
1
vote
0answers
55 views

In momentum theory, what happens if atmospheric velocity is larger than outflow velocity?

I am currently reading up on aerodynamics, essentially the actuator disk concept and momentum theory as it is described in e.g. Basic Helicopter Aerodynamics by Seddon and Newman. There they assume ...
1
vote
0answers
78 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 ...
1
vote
0answers
75 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 ...
1
vote
0answers
168 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, ...
1
vote
0answers
305 views

Efficiency estimation for small-scale (~15cm) propellers

First up, apologies if this isn't quite the place for this; Aerospace is still in Area 51 so there doesn't seem to be a better place for it. If it helps, feel free to give theoretical answers and I'll ...
1
vote
0answers
171 views

effect of internal forces to a glider's descent

This is a continuation of a previous question, with more thinking applied, thanks to a helpful comment. Imagine a glider is airborne in a breezeless sky. The glider is 3 KM high, is traveling at 100 ...
1
vote
0answers
344 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 ...
0
votes
0answers
19 views

Communication between two LEO satellites

Anybody have any idea about any mathematical model to allow communication between two LEO Satellites is possible in space, where two LEO satellites do not know their positions in two different polar ...
0
votes
0answers
36 views

Why does the shock in viscous flow occur sooner than non-viscous one?

Why does the shock in viscous flow occur sooner than non-viscous one? If we want to discuss about drag, which one has bigger drag? This figure may help.
0
votes
0answers
76 views

Position and Tension of Kite/Balloon Tether in Presence of Wind

I wish to solve for the position of a kytoon's (hybrid kite and balloon, with both aerostatic and aerodynamic lift as well as non-negligible drag) tether given the forces present on the kytoon and ...
0
votes
0answers
21 views

Temperature and air flow - are they related?

If I open a window, does the air "changes" (e.g. the $O_2$ concentration) in the room more quickly if there was a temperature difference between inside and outside?
0
votes
0answers
169 views

Magnus effect, Coanda effect, and the Bernoulli principle: What is balancing gravity on a spinning sphere vs. a stationary screwdriver?

I've seen videos of golf balls and screwdrivers levitated by a focused air stream. Reading the comments of these videos (and others), I see explanations of the machanics at work and their cause and ...
0
votes
0answers
38 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 .5*25^2*70=21,...
0
votes
0answers
209 views

Calculating rotor torque out of mass center

Suppose I have an engine with propeller. I know there is aerodynamic force pushing the propeller opposite direction the engine is turning it. One component of this force is creating lift, but second ...
-1
votes
0answers
20 views

About Von karman vortex shedding

Does Von Karman (vortex shedding) effect behind a flat plate, produces moment on that plate which? How to calculate this moment?