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.

FMI: Aero-Tips