On Apr 17, 12:02 am, Jose wrote:
On the other hand, wingtip vortices are a well-researched topic, and
if a Boeing 727's is only 9' in radius,

cite? I remember seeing pictures of wingtip vortices (of fair sized
aircraft) and they looked like they were more than 18 feet across.

Sorry was not cited here, but in other posts. To repeat:

http://www.airpower.maxwell.af.mil/a...ug/carten.html

Yes, I would've thought much bigger too, but then they wouldn't be as
much a threat so far behind an aircraft if they expanded quickly in
diameter. Apparently if flaps or spoilers aren't used, the danger
area behind a 747, for example, extends many more miles than we're
usually taught:

http://www.nasa.gov/centers/dryden/a...4-14-DFRC.html

Still haven't found much on really light aircraft ( 26,000 lbs), but
the concept should be the same, albeit at a much smaller amplitude.
There are equations for calculating the vortex, but they seem hard to
get at on the web.

Of interest: wingtip vortices were first formally written about in
1907 (!), and the use of vertical fins to cut down the drag on wings,
dates over a decade before that.

Regards, Kev