Riding The Storm Out
Thanks for Ryan Motte’s “Coping With Turbulence” in your June 2024 issue. The article didn’t spend much time discussing clear air turbulence. Is it simply not a factor with personal airplanes? Also, can you go into more detail on how to handle a turbulence encounter?
Thanks in advance!
—Charles Klaine, Via email
Clear air turbulence is primarily a problem at higher altitudes. The aircraft most of us fly can’t comfortably get high enough for CAT to be a regular factor. That said, you can use the same basic tools as at lower altitudes. If recent airline-related events are any guide, CAT is becoming more common in the flight levels. We’ll work on a “belly of the beast” article.
Avoiding Vortices
Jim Wolper’s July 2024 article on wingtip vortices was a good review but omitted some details regarding vortices and their behavior near the ground. For example, under some wind conditions, the vortex’s rotation can result in it remaining over the runway, ready to trip up the next light plane’s arrival. Also, do vortices dissipate at greater rates when winds are calm or gusty? Thanks!
—Steve Bening, Via email
Sadly, space didn’t allow us to go into greater detail on how vortices behave close to the ground. Yes, certain wind conditions/runway combinations can result in vortices lingering over the runway after a heavier airplane comes or goes. As Jim also related, a vortex generated by an airplane departing a parallel runway can drift downwind to yours.
One of the keys is awareness and, especially, knowing what the wind is doing at the surface and how the vortices may behave. The Pilot’s Handbook Of Aeronautical Knowledge (PHAX, FAA-H-8083-25C) includes diagrams of many runway/vortex permutations.
That said, we’ll always take the full three-minute delay at towered facilities when departing behind almost anything, since almost anything else is bigger and heavier than us. Doing so doesn’t endear us to ATC sometimes, but their chair isn’t doing 100 knots down the runway, either.
Cooler Hovering
July’s cover article “Playing Slow Flight For Keeps” helps remove some of the “fear factor” when doing slow flight for extended periods. One thing I’m concerned about is keeping the engine cool, since it’s likely putting out a fair amount of power to keep us slow and in control.
Any suggestions on keeping an air-cooled engine happy when there’s not much air moving over it to dissipate heat?
—Andrew Strauss, Via email
Good question. Hopefully, we aren’t in hover mode long enough for it to matter. And, we’ll be at a reduced power setting, so overheating may not be the problem you think it is. That said, in airplanes so equipped, cowl flaps obviously should be open.
Another way to regulate an air-cooled engine’s operating temperature is with the mixture control. At low power settings—say, 50-percent power—there’s no danger of hurting anything if you choose to run the engine well lean of peak exhaust gas temperature (EGT). Doing so uses air instead of the excess fuel of a well rich of peak EGT fuel/air mixture to keep things cool.
Especially when at low altitude and in the traffic pattern to land, we’re not likely to use a technique like hover mode long enough to overheat the engine.
However, if we’re engaged in a longer slow-flight demonstration, it’s a good idea to pay more attention to the engine’s temperature than we might normally.
Good question! Thanks!
