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19 Nov 2006

Afterburners


Afterburners are special devices fitted between the turbine and the nozzle of some turbojets and turbofans. A modern turbine engine is extremely efficient, and there is still a lot of oxygen available in the exhaust stream. The idea behind an afterburner is to inject fuel directly into the exhaust stream and burn it using this remaining oxygen. This heats and expands the exhaust gases further, and can increase the thrust of a jet engine by 50% or more.

The big advantage of an afterburner is that you can significantly increase the thrust of the engine without adding much weight or complexity to the engine.

The disadvantage of an afterburner is that it uses a lot of fuel for the power it generates. Therefore most planes use afterburners sparingly.

6 Nov 2006

So You Want to be an Aircraft Mechanic?

There are a host of reasons why year after year thousands of intelligent individuals attempt to break into the aviation maintenance career field.

They will do anything and everything they can just to get their "Foot in the Door".

Where else are you required to accomplish many tasks with sheer brute force and brawn, exceeding the bodies normal capability? You also must weave your body into unimaginable locations filled with wire and sharp objects, and function with the precision of a surgeon. Our bodies are required to withstand the sun, wind, rain, cold, and the darkness of night. We often use our senses of smell, sound, sight, touch, and even taste to determine whether an item is capable of withstanding the required loads or meeting its objective. Our hands are burned, punctured, smashed, cut, and placed in areas and chemicals that have been deemed too dangerous and harmful for even laboratory animals.

Aviation mechanics must know the systems intimately, and be able to reason, calculate, and rationalize any defect imaginable. These functions must be performed with great speed and accuracy, as humiliation and/or unemployment await the incapable. The mechanic must know, interpret, and attempt to locate vital information in a vast array of books, publications, and bulletins. Then, upon successful accumulation of the data, we must use skills and techniques to produce a job that will sustain lives. Upon completion we must document our every move, and be prepared to enter federal prosecution, which could result in fines, loss of license, and/or sentencing.

Weekends, normal hours, and holidays are often talked about, but seldom enjoyed. Pagers have become as common as the Phillips head screwdriver. In addition, we are expected to be neat, clean, and have a delightful disposition. However, with any job of this caliber, a few frustrations and a little stress is to be expected.

Sometimes it's so good I can hardly stand it myself.

It's no wonder why so many individuals want to be just like me.

5 Nov 2006

SUCK-SQUEEZE-BANG-BLOW!!!!

Whoops! With a title like that you probably think you've hit the wrong website.
While the above title may sound like something out of my writings, it's really just a creative way of remembering the stages of a turbojet engine uses in aircrafts.

Hmmm, that doesn't sound much better, does it?

OK, let's start with the basics.

Most modern passenger and military aircraft are powered by gas turbine engines, which are also called jet engines. The first and simplest type of gas turbine is the turbojet.

In a basic turbo jet, the air enters the front intake (suck) and is compressed by the compressor (squeeze), then forced into combustion chambers where fuel is sprayed into them and the mixture is ignited (bang). The gases which form expand rapidly, and are exhausted through the rear of the combustion chambers and out through the nozzle (blow) providing the forward thrust. Just before the gases enter the engine nozzle, they pass through a fan-like set of turbine blades which rotates the engine shaft. This shaft, in turn, rotates the compressor, thereby bringing in a fresh supply of air through the intake. All of these processes are happening at the same time.


A basic turbojet engine.