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No. 94: Jul-Aug 1994

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Plane Weirdness Made Plain

In SF#93, under the title: "Just Plane Weird," we questioned the long-term persistence of trailing vortices from aircraft wingtips. Could such vortices actually maintain their integrities for several minutes and thus produce the curious tubes of misty air and flapping sounds observed at the end of the Los Angeles airport runway? The answer seems to be YES, as confirmed below:

"Wingtip vortices have a core diameter of 20 to 40 feet and, as they trail behind each wingtip, remain approximately two wingspans apart. Why don't they enlarge in radius and dissipate? The rapid acceleration at the outer edge of the vortex produces low pressure in the core, and this pressure differential creates enough centrifugal force to hold the system tightly together for three to seven minutes. After that, friction takes its course, breaking these stubborn twisters apart into mere turbulence."

The rest of this article deals with how light aircraft can avoid these sometimes deadly horizontal "twisters."

(Manningham, Micah D.; "Wake Turbulence," Private Pilot, p. 69, June 1994. Cr. W.A. Welch)

From Science Frontiers #94, JUL-AUG 1994. 1994-2000 William R. Corliss

Science Frontiers Sourcebook Project Reviewed in:


  • "A sourcebook of unexplained phenomena is therefore a valuable addition to a collection of scientific literature. William R. Corliss has provided this in the past with his source books of scientific anomalies in several subjects, and now he has provided it for astronomy. He has done an excellent job of collecting and editing a large amount of material, taken in part from scientific journals and in part from scientific reporting in the popular or semi-scientific press." -- "The Mysterious Universe: A Handbook of Astronomical Anomalies", reviwed by Thomas Gold, Cornell University, in Icarus, vol.41, 1980

  • "An interesting, systematic presentation of unusual weather [..] This book is recommended for a general audience" --"Corliss, William R., Tornados, Dark Days, Anomalous Precipitation, and Related Weather Phenomena, Sourcebook Project, 1983.", revieweed in Choice, September 1983
  • "..the science is necessarily somewhat speculative, but Corliss's symthesis is based on reputable sources." -- "Corliss, William R. (Compiler). Lightning, Auroras, Nocturnal Lights, and Related Luminous Phenomena" reviwed by Joseph M. Moran, Univ. of Wisconsin in Science Books and Films, Sep/Oct 1983

  • "Before opening the book, I set certain standards that a volume which treads into dangerous grounds grounds like this must meet. The author scrupulously met, or even exceeded those standards. Each phenomenon is exhaustively documented, with references to scientific journals [..] and extensive quotations" -- "Book Review: The moon and planets: a catalog of astronomical anomalies", The Sourcebook Project, 1985., Corliss, W. R., Journal of the Royal Astronomical Society of Canada, Vol. 81, no. 1 (1987), p. 24., 02/1987