R
EVISION
:
-
D
ATE
:
12/29/04
P
AGE
:
18
Copyright
2004 Glasair Aviation, LLC Arlington, Washington All rights reserved
Both problems are amenable to one solution: maintain adequate power
to keep cylinder head temperatures in the “green” range during
descent, and lean to best power mixture (that is, progressively enrich
the mixture from cruise only slightly as altitude decreases). This
procedure will lengthen the descent, of course, and requires some
advance planning.
If it is necessary to make a prolonged descent at or near idle, as in
practicing forced landings, at least avoid the problem of fouled spark
plugs by frequently advancing the throttle until the engine runs
smoothly and by maintaining an appropriate mixture setting with
altitude.
Vortices–Wake Turbulence
Every airplane generates wake turbulence while in flight. Part of this is
from the propeller or jet engine and part from the wing tip vortices.
The larger and heavier the airplane, the more pronounced and turbulent
the wakes will be. Wingtip vortices from large, heavy airplanes are very
severe at close range, degenerating with time, wind and distance. In
tests, vortex velocities of 133 knots have been recorded.
Encountering the rolling effect of wing tip vortices within two minutes
after passage of large airplanes is most hazardous to light airplanes.
This roll effect can exceed the maximum counter-roll available in a light
airplane. The turbulent areas may remain for as long as three minutes
or more, depending on wind conditions, and may extend several miles
behind the airplane. Plan to fly slightly above and to the windward side
of the other airplane’s flight path. Because of the wide variety of
conditions that can be encountered, there is no set rule to follow to