Aero-Tips!
A good pilot is always learning -- how many times have you heard
this old standard throughout your flying career? There is no truer
statement in all of flying (well, with the possible exception of
"there are no old, bold pilots.") It's part of what makes aviation
so exciting for all of us... just when you think you've seen it
all, along comes a scenario you've never imagined.
Aero-News has called upon the expertise of Thomas P. Turner,
master CFI and all-around-good-guy, to bring our readers -- and us
-- daily tips to improve our skills as aviators, and as
representatives of the flying community. Some of them, you may have
heard before... but for each of us, there will also be something we
might never have considered before, or something that didn't
"stick" the way it should have the first time we memorized it for
the practical test.
It is our unabashed goal that "Aero-Tips" will help our readers
become better, safer pilots -- as well as introducing our
ground-bound readers to the concepts and principles that keep those
strange aluminum-and-composite contraptions in the air... and allow
them to soar magnificently through it.
Look for our daily Aero-Tips segments, coming each day to you
through the Aero-News Network. Suggestions for future Aero-Tips are
always welcome, as are additions or discussion of each day's tips.
Remember... when it comes to being better pilots, we're all in this
together.
Aero-Tips 04.07.06
You know about the Bernoulli
principle and how Newton's laws apply to lift. But have you
ever heard of the Magnus Effect?
The Magnus Effect can best be visualized by looking at a
cylinder rotating in an airstream. The local air
velocity near the cylinder is composed of the airstream
velocity plus the cylinder's rotational velocity -- a boundary
layer of air means local velocity is lower the farther air is from
the cylinder. If the top of the cylinder is rotating in the
same direction as the airflow, local velocity on the top is higher
than local velocity on the bottom.
There's a stagnation point at the level where air flows
either up or down around the cylinder. A second stagnation
point exists behind the cylinder where air paths rejoin.
There's an upward flow ahead of the cylinder and downward behind
it.
Under (and over) pressure
This difference in flow results in lower pressure on the top of
the cylinder than on the bottom. This in turn causes an
upward force called…the Magnus Effect. It's the same
force that causes a baseball to curve, or a golf ball to slice.
An airfoil with a positive angle of attack creates airflow
circulation as the wing's sharp trailing edge forces the aft
stagnation point aft of the wing, while rebounding from the leading
edge forces the forward stagnation point ahead of the
wing.
Aero-tip of the day: Next time someone
asks you to explain how a wing develops lift, remember Bernoulli,
remember Newton…and don't forget Magnus.