Talk:Aerodynamic force

Adding References

This is a response to Mr swordfish,

I have read your comments about adding references to all edited work. Therefore I am going to restore all of my minor edits, and add references to them. I am also going to reference my new edits, and from there you can hopefully notify me here through the talk page about any other edits that must be done.

Sincerely, Salim — Preceding unsigned comment added by Salim Daher (talk • contribs) 16:19, 25 January 2015 (UTC)

Adding Pictures

I've tried to add couple of pictures but it did't work. If you know hot to add pictures follow the links down below and add them to where its's specified.

The car's aerodynamics

http://www.kasravi.com/cmu/tec452/aerodynamics/aero01.jpg

Pressure in Forces http://www.copters.com/aero/pictures/Fig_2-18.gif — Preceding unsigned comment added by Salim Daher (talk • contribs) 07:59, 27 January 2015 (UTC)

More Information

More information on aerodynamics and moments

http://aerostudents.com/files/introductionToAerospaceEngineering/AerodynamicsForcesAndMoments.pdf

There should be more information on pressure:

http://www.copters.com/aero/total_force.html — Preceding unsigned comment added by Salim Daher (talk • contribs) 08:03, 27 January 2015 (UTC)

Recent proposed changes

A substantial change to the article was made today. I have reverted it pending consensus on the talk page. The proposed versionis here: https://en.wikipedia.org/w/index.php?title=Aerodynamic_force&oldid=644372323 Please discuss the pros and cons of this proposed version. Mr. Swordfish (talk) 13:14, 27 January 2015 (UTC)

To be discussed

This Edit have been restored feel free to help editing on it.

Definition Aerodynamic force is exerted on a body by the air (or some other gas) in which the body is immersed, and is due to the relative motion between the body and the gas.

Overview Aerodynamic forces are different from contact forces that occurs when a solid object comes in touch with another solid object. This is because Aerodynamic forces happen when a solid object comes in contact with a fluid, and fluids can change in shape and form. The fluid flows around the body maintaining a physical contact at all points. This makes every point to be considered as point of contact, in which mechanical forces are applied at every point of the solid body. These forces falls under aerodynamics forces, and they are transmitted through the fluid’s pressure. The net aerodynamic force over the body is due to the pressure and shear forces integrated over the total exposed area of the body. Aerodynamic force arises from those two causes.

• the normal force due to the pressure on the surface of the body
• the shear force due to the viscosity of the gas, also known as skin friction.

Forces in Aerodynamics The aerodynamic force on a powered airplane is commonly represented by three vectors: thrust, lift and drag.

• Thrust: Moves an airplane forward and can be created by propeller or jet engine.
• Drag:The force the holds an airplane back and parallel to the direction of relative motion.
• Lift': The force component perpendicular to the direction of relative motion, and is responsible for keeping an airplane airborne.

Lift can be explained through three theories: Bernoulli's principle, the Coanda effect, and Newton's third law of motion. [7][8]

In addition to these forces, the body may experience an aerodynamic moment also, the value of which depends on the point chosen for calculation. <br

Velocity Distribution

Knowing velocity distribution can be used to determine Pressure distribution and the net force using Bernoulli equation.

• Ideal Fluids:

-A fluid has no boundary layers -The surface of the solid object is considered as a stream line. -Bernoulli's equation can be used to determine pressure distribution as long as there is energy is not added to the flow and the velocity is low.

• Fluids with boundary layers:

-External flow responds to the edge of the boundary layer -Pressure on the surface is imposed from the edge of the boundary layer.

• Fluids with separated boundary layers from the surface of the body:

-Cannot specify a certain velocity to be determined -Solve equations expressing a conservation of mass, momentum, and energy for the fluid passing the object.

Shock Waves
The air flowing over the wing of the airplane accelerates above the speed of sound when its speed reaches above March.7. At this point the airplane is compressing air molecules because it’s at a high speed that air molecules won’t be fast enough to move around the airplane. This cause a shock wave and it’s dangerous since it effects controlled surfaces of the airplane. Shock wave have been barrier for manufactures to make faster planes for many years, until it was solved by moving certain control surface of the wave’s direct path and by using swept-back wings.

More about Aerodynamic Forces

• Measuring Aerodynamics Forces

-Wind tunnels.
-Hyper sonic shock tunnel

• Uses of Aerodynamic Forces

-Airplanes companies and manficaturies

-Automobile Vehicles manufactories

Summary For any object immersed in a fluid, the mechanical forces are transmitted at every point on the surface of the body through pressure, which acts perpendicular to the surface. The net force can be found by integrating (or summing) the pressure times the area around the entire surface. For a moving flow, the pressure will vary from point to point because the velocity varies from point to point. For some simple flow problems, we can the pressure distribution can be determine (and the net force) by using Bernoulli's equation if the velocity distribution is known

References

Cleaning up & incorporating edits

Looking over the history, it seems that some of the edits that were added and then removed would be useful if they were tidied up a bit and clarified (for example the connection to fluid dynamics vis-a-vis aeorodynamics force not being a contact force). I'll try and do this in the next couple of weeks.

There is also a contradiction: Aerodynamic force is exerted on a body by the air (or some other gas) BUT thrust and it is also an aerodynamic force (since it also acts on the surrounding air) . So THRUST is NOT an aerodnyamic force according to the definition at the top. Lehasa (talk) 16:19, 1 February 2015 (UTC)

I think that restoring this sentence is also valuable. "Lift is generally explained by three theories: Bernoulli's principle, the Coanda effect, and Newton's third law of motion." . The main interest in aerodynamic force seems to be in terms of airplanes and airfoils. Perhaps this should also be mentioned. Are there any other areas where this is applied? (propellors, really high buildings that must not be airfoil shaped?) Lehasa (talk) 16:26, 1 February 2015 (UTC)

I would suggest familiarizing yourself with the material and discussion at Lift_(force) before attempting to summarize it here. At the very least, the two articles should not contradict one another.

Regarding thrust not being an aerodynamic force, Newton's third law says that when the propeller exerts a force on the air, the air exerts an equal but opposite force on the propeller. So in the case of thrust, the air is exerting a force on the the propeller and so thrust falls within the definition of aerodynamic force.

And, yes, there are many areas other than fixed-wing aircraft where aerodynamic force is applied. Mr. Swordfish (talk) 15:08, 2 February 2015 (UTC)

Well if you are saying that by Newtons' 3rd law there is always an equal and opposite force, you are essentially saying that this "Aerodynamic force is exerted on a body by the air" is redundant and should be writen as "Aerodynamic force is a force exerted on a body by the air, OR on the air by a body" - which would include a fan, a balloon deflating, etc. Sometimes people intentionally restrict definitions in order to make discusions more manageable and precise. Presumably you know that in free body diagrams, one only considers the forces that are acting on the body, even though everybody knows that there are equal and opposite forces that are not shown. And ... of course there are occaisional exceptions when one does need to consider the pair of forces on an FBD, but this is not the point (I am just pointing this out now so that you don't have to later). Lehasa (talk) 03:03, 4 February 2015 (UTC)

Fluid/gas/air

My knowledge of this field is dated and limited. Aerodynamic force has been used when referring to fluids. To show that it is not just my poor memory, a quick web search finds: https://www.grc.nasa.gov/WWW/K-12/airplane/presar.html

My minor suggestion is to comment on and clarify this; i see that this page: https://en.wikipedia.org/wiki/Aerodynamics tries to do that in its second and third sentences, but imho doesn't nail it. Perhaps some history on anachronistic vs obsolete vs sloppy-or-just-plain-wrong usage might be interesting and useful. — Preceding unsigned comment added by Sbrozell0 (talk • contribs) 18:04, 30 May 2018 (UTC)

@Sbrozell0: Thank you for bringing your concern to this talk page. The NASA page that you cite does indeed refer to "fluid" in reference to air. The first two bullets that you are alluding to are general—they don't necessarily refer to a lifting body, like a wing or propellor. So here are two observations:

• While air and water are both fluids, it's better to talk about air or gas here, which is to say that we're talking about a compressible fluid. Incompressible fluids exhibit some different behaviors, such as cavitation.
• The first two bullets are supposed to condense material found in: Hurt, H.H.Jr. Aerodynamics for Naval Aviators, which is available as a fully searchable PDF at the link given here. You are welcome to try a better summary than what's currently in the article, using either Hunt and/or the link that you provided.

Sincerely, HopsonRoad (talk) 20:10, 30 May 2018 (UTC)