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).

Filter by
Sorted by
Tagged with
1
vote
0answers
33 views

How to calculate the positioning angle of a rocket for launch

I am building a model rocket. I want it to end up in a specific position. If I am taking into account the acceleration, starting position, end position, mass, and wind speed, how do I find the angle I ...
4
votes
2answers
1k views

Variables in calculation of drag coefficient

Okay, so I looked up drag force equation, and I found that the equation involved the drag coefficient. Then I looked up the drag coefficient, and the equation for it involved the drag force. ...
0
votes
1answer
116 views

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?
14
votes
4answers
2k views

Why does fluid pressure decrease as fluid velocity increases according to Bernoulli's principle?

I’m studying aerodynamics. I understand Bernoulli’s principle very well, I just can't wrap my head around why pressure decreases as velocity increases. Like the garden hose example: if you cover the ...
0
votes
0answers
26 views

How can I control the airflow in a car by open or closed window configuration?

What car window configuration will let air in by me and make / let it exit away from me. I have a large divider between front and back seats that covers much, but not all the plane between. People in ...
-2
votes
2answers
135 views

Will the hose eventually become a straight hose? [closed]

A garden hose on the ground, water with enough speed flows out at its end. In the beginning, the hose is bent. Assuming only the force caused by bending and the friction force on the ground act on the ...
-1
votes
2answers
81 views

Why does the airflow at the leading edge of the wing curve toward the trailing edge of the wing?

Why does the airflow at the leading edge of the wing curve toward the trailing edge of the wing? Is it because the leading edge of the wing generates high pressure? High pressure pushes the air from ...
3
votes
1answer
44 views

Is the well known textbook-formula for net-thrust oversimplified or do I have a misinterpretation?

In order to understand how Jet-Engines works I came across the "famous" formula for net-thrust: https://en.wikipedia.org/wiki/Turbojet#Net_thrust $F_{thrust} = Q_{out} \cdot v_{out} - Q_{in}\...
1
vote
0answers
39 views

How is the energy dissipated by drag split between sound waves and turbulence?

Consider an object of radius $R$ traveling at a constant, slightly subsonic or supersonic speed through a homogeneous fluid, in conditions of very high Reynolds number. Because the object experiences ...
0
votes
1answer
19 views

“Trapping” boundary layer to reduce skin friction drag?

One of the propsed ways to reduce skin friction drag is by maintaining laminar flow. But to do this normall requires a low Reynolds number. But a low Reynolds number is in itself a recipe for extra ...
-2
votes
1answer
36 views

Wind tunnel experiment that measures lift (not the lift coefficient)?

Does anyone know of a wind tunnel experiment on a wing or airplane that measures the absolute amount of lift (not the lift coefficient); and demonstrates conclusively that the lift generate by a wing ...
14
votes
4answers
2k views

Can a Styrofoam box bounce back into a moving van?

I just came across this video. A styrofoam box falls out of a moving van, bounces off the road and lands back in the van. How can the box land back so precisely inside the van?! Usually, I would ...
0
votes
2answers
118 views

Flight time of spherical bullet fired horizontally versus dropped vertically / effect of crosswind on spherical car

Would a spherical bullet fired horizontally from a musket stay aloft longer than a spherical bullet dropped from the same height? I know two similar questions have been asked (Will a bullet dropped ...
-4
votes
2answers
185 views

How can Lift = Weight; if airliners fly with Thrust-to-Weight ratios = 0.3? [closed]

Question: I'd appreciate it a lot if anyone could explain how lift can equal the weight of an airplane in flight (Lift = Weight), if these airplanes have thrust-to-weight ratios of 0.3 (e.g. Boeing ...
257
votes
15answers
72k views

What really allows airplanes to fly?

What aerodynamic effects actually contribute to producing the lift on an airplane? I know there's a common belief that lift comes from the Bernoulli effect, where air moving over the wings is at ...
0
votes
3answers
395 views

Aircraft Thrust to weight ratio contradiction with energy conservation

Usually, airliners have (Thrust/Weight) T/W ratio in the range of 0.2 to 0.8 and for steady flight W = lift My question is, for example, that Antonov 225 has Thrust/weight: 0.234 for max takeoff ...
1
vote
1answer
41 views

Do airplanes circulate the air sideways in flight?

When airliners fly through clouds it looks like they are circulating the air sideways. See Image. The wings are pushing the air flown through downwards, which circulates the air each side of the ...
2
votes
3answers
98 views

Ceiling fans with just one large winglet? [closed]

I am from India and in India ceiling fans have generally three wings. Today while laying on my bed a question came in my mind. First of all, I know that if we use just a single wing at a time of same ...
5
votes
6answers
4k views

Is it really impossible for Bumblebees to fly?

According to some source or other (I forget which now) it is theoretically impossible for bumblebees to fly by virtue of their size/bulk/aerodynamic properties. Is this old adage apocraphyal or true? ...
1
vote
2answers
45 views

Can an airship tack? [closed]

A sail ship leverages the keel’s resistance to turning moments to allow a wind crossing a sail at an angle to tack, achieving a speed greater than the driving wind. But is it possible at all for an ...
0
votes
0answers
8 views

Righting moment of a flattened balloon

Would a flattened round balloon tend to orient vertically or horizontally, assuming neutral buoyancy? Does this shape provide a righting moment against pitch and roll? By flattened, I do not mean “...
6
votes
4answers
8k views

What exactly is the 'lift' of a sailboat as explained by Bernoulli principle

I have heard that when a sailboat is sailing against the wind, it operates on the principle of 'lift'. I am unable to understand the explanation, based on Bernoulli principle, completely. My question ...
4
votes
1answer
119 views

Do helicopters and planes fly by different reasons?

In the case of the helicopter, it is pretty clear (well, for me) that it gets lift by pushing air downwards. And as a consequence, there is more pressure below its blades than above. But on the other ...
14
votes
6answers
6k views

How much effect does the Bernoulli effect have on lift?

I understand that the Bernoulli effect is a flawed explanation for the cause of lift, and does not cause much at all, but how much? Is there any experimental data on the force caused by the ...
0
votes
1answer
306 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 ...
1
vote
1answer
202 views

How the wing creates lift? Why critical angle of attack is 16.5" for a supersonic jet and a kite?

I have seen many references on how the wings create lift, most of them overplaying effect of Bernoulli's rule. But nowhere has there been any consideration given to this important factor: Let's ...
1
vote
2answers
94 views

Can we Predict the Trajectory of a hypersonic missile?

I read in a newspaper that we can't predict the trajectory of a hypersonic missile and this property makes the missile undetectable. But I couldn't understand why can't we predict it's trajectory? ...
0
votes
1answer
22 views

Are aerodynamic car rims really aerodynamic?

Especially new electric cars often come with aerodynamic wheels that look like a turbine with twisted blades. What is the point of this? I mean, e.g. in cycling they use just a simple disc wheel when ...
1
vote
1answer
567 views

Kutta-Joukowski theorem applied on a Joukowski airfoil (derivation)

I have a doubt about the derivation of the Kutta-Joukowski theorem for a Joukowski airfoil. I know the results, but my main objective is to know how get these ones. Consider for the initial plane a ...
0
votes
1answer
146 views

Understanding hyperloop design

I am trying to understand some choices of hyper-loop designers. The effort seems to be focused on trying to bring a near vacuum (space-like) environment to ground level. Why would it not be easier ...
5
votes
2answers
632 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
3answers
2k views

Terminal Velocity of a Car

When explaining how a car reaches its terminal velocity, is it solely down to how aerodynamic the car is? My thoughts are that if you have a fixed mass $m$, then the contact frictional force will be ...
0
votes
0answers
36 views

Velocity induced by a straight vortex filament

Consider a straight vortex filament as shown below. At each point, there's a point vortex of strength $\it T$. Consider that a point $P$ is there on the outermost circle of flow induced by the vortex ...
3
votes
1answer
75 views

Effects of altitude on paper airplanes

If one were to fly a paper airplane at the Dead Sea (400 meters below sea level) and another identical paper airplane at the peak of Mount Everest (8800 meters above sea level) would there be any ...
1
vote
2answers
58 views

Why do airplane wings have fins?

I was watching this video and it shows that adding fins on the wing helps the air get turbulent on the upper part of the wing, which forces the air to stay longer, and ultimately this helps with lift. ...
0
votes
0answers
7 views

How to calculate strouhal number/vortex shedding frequency of the airfoil using mathematical approach?

As a part of my thesis, I am trying to find when the airfoil starts to flutter by changing pitch angles. I've computed the results in ANSYS Fluent. But now I've to calculate the same using a ...
19
votes
1answer
4k views

If an astronaut got stuck in the middle of a space station, can he propel himself towards a wall by blowing air out of his mouth?

Consider the astronaut as floating in the middle of the "Kibo" (ISS module) without him having any initial motion. The module has a diameter of 4.2 m (inner), and the goal is to reach any of ...
-2
votes
1answer
98 views

Why are turbines more effective than propellers on airplanes? [closed]

I have read this question: Why do turbine engines work? The compressor generates a certain volume of air at a high pressure. In the combustion chamber, this air is heated - this leads to a much ...
56
votes
4answers
6k views

Why are aerodynamic / streamlined shapes always stumpy at the front?

I'm building an autonomous boat, to which I now add a keel below it with a weight at the bottom. I was wondering about the shape that weight should get. Most of the time aerodynamic shapes take some ...
2
votes
2answers
63 views

What is the purpose of the roll maneuver on a rocket?

I have watched several videos on both rocket launches, ballistic missile launches, even a really cool one by Northrup Grumman on launching a nuclear missile. (https://www.youtube.com/watch?v=...
0
votes
1answer
52 views

What is the effect of “The Ground Effect” on a load bearing structure?

If a train was made to utilize the ground effect, (or plane made to follow a rail) not to have any contact with the ground other than air, would the rail need to be so heavily built since the air is ...
12
votes
1answer
11k views

Book recommendations for fluid dynamics self-study

I have my bachelors degree in engineering science: computer science, option electrotechnic. I have a good understanding of basic mechanics and dynamics, calculus (differential equations). The books I'...
1
vote
1answer
37 views

What is the Reynold's number of a plate moving through a fluid?

I read here that the equation of resistive drag $F = -bv$ can be used, assuming the particle is moving through a fluid at relatively slow speeds where there is no turbulence (i.e. low Reynolds number,...
0
votes
0answers
23 views

Is there a roof pitch angle for a hip roof that is most likely to withstand strong winds?

All other things being equal, what roof pitch (angle from horizontal) for a hip roof is likely to experience the least lift (or other relevant forces) and best withstand strong winds? Any of the ...
0
votes
1answer
40 views

How does a bullet achieve its stability when fired?

As far as I know, darts, arrows, and airplanes have the center of gravity(CG) ahead of their center of pressure(CP) and often have fins at the rear to achieve stability. Contrary to these, bullets ...
0
votes
1answer
33 views

Vortex formation in an airfoil

How is a starting vortex formed when an airfoil (i.e cross-section of wings of a plane) starts to move?
1
vote
0answers
24 views

What is a formal proof for Kutta-Joukowski Theorem in compressible flow?

Texts, such as Drela, Flight Vehicle Aerodynamics, indicate that the Kutta-Joukowski Theorem holds in compressible flow. Indeed, the KJT seems hold in linearized supersonic flow around a 2D flat plate....
3
votes
1answer
405 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 ...
0
votes
0answers
18 views

Calculating (transient) rate of cycles of practical thermodynamic engines (turbojet, multi-cylinder car engines etc..)

I tried to make a plan for a turbojet engine with my physics knowledge and I'm stumped in the first step. For any sustained real engine, I need to somehow take a fraction of the energy output and use ...
-1
votes
1answer
46 views

Explaining Bernoulli's Principle

I'm trying to explain Bernoulli's principle (in the context of flight) to an audience that doesn't have a physics background. So I'd like to avoid mentioning technical concepts as much as possible. ...

1
2 3 4 5
14