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 good pilots, we're all in this
together.
Aero-Tips 02.14.06
Yesterday we began to
translate the language of an airplane’s electrical system by
visualizing its components as parts of a water-flow system. We
illustrated flow from a battery "water tank," through a master
switch "spigot" to a buss "distribution pipe." From there
electricity flows through switches like "spigots" from the buss, to
power equipment ("loads") on the way to flowing to the ground. Are
you with me so far?
This system works only as long as there’s "water" in the
battery "tank." Wouldn’t it be great if there was some way to
take that "water" from its puddle on the ground and pump it back
into the tank?
Please note: This visualization is not technically correct
-- but it does a superb job of helping pilots comprehend
what’s going on with the electrical system to accurately
monitor it and troubleshoot problems. Engineers, mechanics and
purists, please forgive this teaching tool.
Alternator (or Generator) Think of the
alternator/generator as a "water pump" that picks up "water" from
the ground and pumps it back into the battery "tank" (okay,
that’s real inaccurate technically, but it’s perfect
for understanding in our illustration). Water flow must always be
toward the tank to keep it filled. To assure this, the pump propels
water under slightly higher pressure than the ambient pressure of
water in the tank. The pump can also power the entire system even
if the tank itself is not kept full, by pushing water through the
tank. Equipment being powered, however, is not protected against
surges in power flow without the buffer of the tank, and there is
no reserve of pressure should the pump fail.
(Note: the alternator has to be powered by
something. Let’s say we’ve got a four- or six-cylinder,
gas engine to run the pump. Might as well hang a propeller on it
while we’re at it -- all this electricity does us no good if
the airplane won’t fly!)
In a perfect world the alternator would restore power to the
tank precisely at the rate it is being used at the time... any more
could "overfill the tank," leading to (in a battery) overheat and
an explosion hazard, while any less would not be able to keep up
with the rate of "water," or electrical power loss. Since we use
electricity at different rates throughout a flight, we need
something to regulate the output of our alternator "pump."
That’s tomorrow’s topic.
Aero-tip of the day: It may be helpful to
visualize electricity as the flow of water to better understand its
function. We’ll continue this discussion in tomorrow’s
Aero-Tips.