Talk:Magnus effect
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Although discovered by Heinrich Magnus in 1853, it remained little studied until the 1920's and 1930's. Most all of the research was done in Germany. The Magnus Effect force can be very powerful, and was studied first and utilized in hydrodynamics, and then came aerodynamic utilization and measurements.
Probably the best book written on the subject, in order to understand it, was By Anton Flettner in a translation published in the U.S. ( see Wikipedia discussion under "Anton Flettner" Also: "Applied Hydro- and Aeromechanics," by L. Prandtl and O.G. Tietjens, McGraw-Hill Book Company Inc.,
1934.
Note: Anton Flettner was the first to use rotating cylinders to produce Magnus Force to drive a wind driven ship. Also noteworthy, was the fact that this was the only sailing ship that could be driven in reverse - simply by changing the rotation direction of the cylinders! Note: See also the NASA web site that discusses the Kutta-Joukowski lift theorem, which explains the Magnus Force
and provides an equation to estimate its magnitude. This site also mentions the Flettner-proposed wind driven ship that used an engine to spin a cylinder. (A picture of the ship is shown.) It further notes that: "the propulsion force generated was less than the motor would have generated if it had been connected to a standard marine propeller!" (www.grc.nasa.gov/WWW/K-12/airplane/cyl.html) Stephreg 20:42, 30 July 2006 (UTC)
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[edit] Tennis
About this phrase in today's copy of this article, "Isaac Newton described it and correctly theorised about the cause 180 years earlier after observing tennis players in his Cambridge college." -- where does it say tennis was available during Issac Newton's time? The Tennis article says otherwise. Was a tennis-like game available, and what was it called? Mdrejhon 20:30, 19 June 2007 (UTC)
Not to worry i think. Tennis has been around since the early 15th century. You see it mentioned in journals and chronicales contemporary with Joan of Arc, for example. That said, the kind of ball being used in Newton's day would have been quite different. The game was still court tennis then. The "modern" game of tennis is lawn tennis - adapted for play outdoors on something like a putting green in the 1870's. But it was still "tennis" before that. Restricted to the upper classes as "court tennis." Ken2849 15:56, 20 September 2007 (UTC)
[edit] Turbulent/laminar flow
- "This is not the only way of describing the Magnus force. The separation of the turbulent boundary layer of the flow from the ball is delayed on the side that is moving in the same direction as the free stream flow, and is advanced on the side moving against the flow..."
The wording here implies that there are two complementary explanations of the same force (velocity difference and boundary separation). However, I wonder if they are actually two independent physical contributions to the force (i.e. two additive forces), and not just different descriptions of the same phenomenon? If so, the text is misleading. Mtford 07:54, 5 October 2007 (UTC)
[edit] A better description of Magnus Effect
Here is a link that offers more on flow seperation of Magnus Effect, with a better diagram (although deflection of flow is exaggerated, it does at leas show a deflected flow).
http://www.geocities.com/k_achutarao/MAGNUS/magnus.html
As mentioned above, I also wonder if it's a combination of the small amount of attached spinning air causing some direct resistance to the air flow as well as causing seperation.
Jeffareid 17:20, 12 October 2007 (UTC)
[edit] Spinning Ball Potential Flow Simulation Image
I just uploaded a spinning ball potential flow simulation image that you might consider for inclusion in this article. Syguy 18:48, 23 October 2007 (UTC)
[edit] Incorrect Description
The effect of different velocities on the top and bottom surfaces actually acts AGAINST the Magnus effect. In the case of the picture on the page, the higher pressure is on the bottom. The boundary layer effect is greater than this effect however, thus the conclusion is, of course, accurate. —Preceding unsigned comment added by 209.202.5.230 (talk) 03:26, 27 March 2008 (UTC)
