Wednesday, February 1, 2017

Embrace the Suck, Squeeze, Bang, and Blast

One of the things that any basic pilot ground school covers is how engines create power. Jet engines and piston engines have the same four stages:
  • Intake
  • Compression
  • Combustion (also commonly called "Power")
  • Exhaust
It's easier to remember them the following way (although you do need to know the "proper" names above for the written exam)
  • Suck
  • Squeeze
  • Bang
  • Blast (or "Blow")

How jets and pistons create these stages is much different. Jets use an almost seamless process, where one stage flows in a line from one to the other. Pistons do them in separate stages, one for each stroke of the piston. This is why 4-stroke engines are called that: one stage of the 4 cycles occurs during each stroke.

Since most people learn to fly in piston airplanes like Cessnas and Pipers, almost all of the time spent on the engine power cycle is spent in ground school on the piston cycle. Unfortunately, it often comes down to rote memorization, since it's hard to see inside an engine to watch what is actually going on.

That all changed recently, however. Thanks to the wonders of high-def, super-slow-mo cameras and YouTube, there are videos that show this process as it happens. Two very good ones were in my email this week.

The first one is by one of YouTube's better channels, Smarter Every Day. They have close to 5 million subscribers for a reason. In the following video, he visits a couple of people who have created a see-through piston engine, gives a review of the basics of an internal combustion engine, and films it in action. If you want to skip the setup, just go to about 4 minutes in:


The second one is by Warped Perception, a channel that films things in unusual ways. It uses the same sort of video equipment and engine, but focuses more on trying different types of fuel to see how it looks different inside the combustion chamber:


These exact principles govern the Lycoming or Continental engine under the hood of your training aircraft. Even if you already understand the power cycle, they're still amazing videos to watch.

See you next Wednesday!


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The author is an airline pilot, flight instructor, and adjunct college professor teaching aviation ground schools. He holds an ATP certificate with ERJ-145 and DHC-8 type ratings, as well as CFI, CFII, MEI, AGI, and IGI certificates, and is a Master-level participant in the FAA's WINGS program and a former FAASafety Team representative. He is on Facebook as Larry the Flying Guy, has a Larry the Flying Guy YouTube channel, and is on Twitter as @Lairspeed.

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