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Archive 1 |
It would be nice to describe what each variable represents and how it is determined, especially the area "A". —Preceding unsigned comment added by 129.107.97.131 ( talk • contribs)
It'd be a good idea on the aircraft section to make sure you differentiate between Cd and Cdmin, since the Cd min values given in the reference page are valid only for certain types of flight... besides all that, there's also the question of whether or not it's set up for Cdi or Cdo...
(edit began here, previous segment was unsigned) Cd really needs to be entirely separated in this article. It is very inconsistent in that it is combining Cd and Cd(induced) far too often. It might also be beneficial to state that the Cd itself has no meaning outside of Cd*ref area. That value is the 'equivalent flat plate area' and Cd is initially derived from Flat plate area/reference area, not magically created or tested for.
Mentioning the derivation of Cdo, which is done either using 'wetted area'*'aerodynamic cleanliness' or by individual parts being summed up, and the aerodynamic interference being introduced.
Cdi, induced Cd through lift, is ENTIRELY different, and needs to be clarified as such. This is why a vehicle like an indy car, which has an extremely low aerodynamic cleanliness value, has such a high Cd(a very high negative lift keeps the car on the ground). Lift induces drag via the equation: Cd=Cdo+(Cl^2/pi*AR*e). e is the wing (lifting surface) effiency factor, and AR is the Aspect ratio of the plane, Span^2/wing area. 164.107.199.93 05:54, 24 January 2007 (UTC)Jason Mead
Cars don't have the same induced drag as air vehicles because they are much closer to the ground. The ground effect doesn't allow as much of a vortex to occur, and the induced drag would be lower than expected.
I just found this comment in the article —Ben FrantzDale 16:38, 26 April 2007 (UTC):
These 2 articles should be merged; I see no reason why the 2 pages are separate. The two topics are about the same thing, except it makes it more inconvenient by having another link to the drag equation page. "drag equation" should be redirected to the "drag coefficient" page Subheight640 23:08, 24 June 2007 (UTC)
I moved a substantial portion of the material that was in this article to a new one entitled Automobile drag coefficients. Rracecarr 18:42, 31 August 2007 (UTC)
I think that the article should be clearer that the equation given does not work in all scenarios. The larger the velocity the more the drag becomes linear, and thus deviates from the quadratic dependence of the given equation. —Preceding unsigned comment added by Moto Perpetuo ( talk • contribs) 05:41, 17 January 2008 (UTC)
Very nice, very well explained, but, how the hell does someone determine the drag coefficient? Where it comes from?
—Preceding unsigned comment added by 200.144.145.32 ( talk) 12:58, 13 March 2006
I've always seen CD rather than Cd. Why does this article not match this one? -- Anthony5429 ( talk) 19:28, 24 January 2009 (UTC)
I am an aerospace engineer. The lower case "d" is only used for a 2-dimensional drag coefficient such as of a wing cross-section(airfoil). A capital "D" is used for a 3-dimensional drag coefficient for a whole wing or a vehicle.
--
Integracer (
talk)
19:42, 15 May 2009 (UTC)
I like the "measured drag coefficients" diagram.
Please add a couple more shapes to the diagram:
I'm pretty sure you already have *one* of the first 2 shapes, but which?
Thank you. -- 68.0.124.33 ( talk) 15:06, 30 July 2009 (UTC)
I think that adding how to calculate the drag coefficient would be important to not only this page but to other page like drag force and ballistic coefficient pages. Here is an example of the NSL equation for the x direction of how the calculation would be done.
Fd=Force of drag (N)
M=mass (kg)
ax=acceleration in the x-axis
=density of air
v=velocity (units aren't important because you will be making a ratio of final vs initial velocities)
C=coefficient of drag (unitless)
A=cross sectional area
Gulielmi2002 (
talk)
15:30, 11 December 2009 (UTC)
In the table near the end of the artcle, please check the values for spheres. I'm not certain, but I think they're off by a factor of greater than 10. ike9898 ( talk) 19:58, 9 February 2010 (UTC)
In the intro paragraph the article states: "The drag coefficient is always associated with a particular surface area". But then the article goes on to list lots and lots of drag coefficient values for various shapes - and never mentions an associated area. How is one to interpret this? Xmrs ( talk) 21:55, 9 February 2010 (UTC)
Notice that the coefficients for rough sphere and smooth sphere are exchanged. It should be 0,1 for rough sphere and 0,4 for smooth sphere. —Preceding unsigned comment added by 85.243.31.73 ( talk) 14:46, 11 February 2010 (UTC)
Notice that the coefficients for rough sphere and smooth sphere are exchanged. It should be 0,1 for rough sphere and 0,4 for smooth sphere.
Notice that the coefficients for rough sphere and smooth sphere are exchanged. It should be 0,1 for rough sphere and 0,4 for smooth sphere.
I seriously doubt the Merc E-Class counts in good science.
I would also expect it is not the lowest Cd of all time.
A table perhaps? —Preceding unsigned comment added by 81.174.174.31 ( talk) 09:11, 4 March 2010 (UTC)
Abelcarvalho ( talk) 14:50, 11 February 2010 (UTC)Abelcarvalho
will someone please check if the following numerical info is available in the article: [1] , [2] —Preceding unsigned comment added by Saeed.Veradi ( talk • contribs) 05:20, 5 June 2010 (UTC)
It might be helpful to condense or clarify the table data on flat plates. I feel that it is misleading, since I am finding many different values for drag coefficient when considering the length-width ratio. Some of the values I've found have been 1.15-1.17 for L/d=1 [3], to 1.28 [4], and 1.98 for infinitely long flat plates.
The table at the top of the article gives cone's a Cd of 0.50, without specifying the sharpness. That's misleading (it mislead me).
According to: http://www.aerospaceweb.org/question/aerodynamics/q0231.shtml a nose cone's Cd can be approximated (sub-mach speeds) by Cd = 0.0112 * (half-vertex angle) + 0.162, thus can span a considerable range. A cone with a 10 degree angle would have a Cd = 0.274, very different from 0.50.
The current table should be amended to specify that the cone pictured is for a half-vertex angle of 30 degrees, and the above approximation should be added into the article somewhere. —Preceding unsigned comment added by 122.57.68.104 ( talk) 01:21, 9 March 2011 (UTC)
The drag coefficient Cd is a scalar, or as the article puts it "a dimensionless quantity". If that is the case, then why is bold face used, i.e. why is it denoted by Cd in the first line? Bold face is reserved for vectors. — Fly by Night ( talk) 13:23, 8 May 2011 (UTC)
i removed Cd=16720/Rel^1/2 this is nonsense ,this relation is incorrect form of Cd=1.382/Rel^(1/2) which is only valid for laminar flow past a plate — Preceding unsigned comment added by 93.172.111.55 ( talk) 15:42, 31 May 2011 (UTC)
I just added that Cw is another way to write drag coefficient, based on http://www.vectorbd.com/peugeot/archive/General/2003/Mar/0063.html, the only source I could find. Correct me if I'm wrong. DirkvdM 07:48, 13 September 2006 (UTC)