By understanding how key parts of your aircraft function you can become a much safer pilot or mechanic. Learning about the functionality of your aircraft cylinders is one area where you can quickly grasp an understanding of a crucial component of your aircraft.
This article will be referring to a four cylinder aircraft engine for the sake of simplicity.
You may assume that aircraft engines are very similar to automobile engines, but they are quite different. Two major differences include the reliability and the power output. These will be discussed in detail later within this article.
First, you need to understand how an aircraft cylinder works.
The intake stroke occurs moving the piston down as fuel and air enter the cylinder through an intake valve. Once this single stroke has completed, the intake valve closes, blocking any other air or fuel from entering.
After this occurs, the crankshaft continues to rotate during the compression stroke. As this happens a few things occur simultaneously: intake and exhaust valves close, the piston moves upwards, and the fuel-air mixture is compressed.
Now starts the fun stuff. An electric spark jumps across the spark plugs as the piston reaches the top of the stroke. This ignites the compressed fuel-air mixture causing it to burn. If you know anything about physics, then you know that as the mixture burns, it expands. This forces the piston downward, driving the crankshaft around again.
Lastly, the exhaust stroke takes place. This is the point where the piston reaches the bottom of the stroke and the exhaust valve opens, releasing excess gas.
Aircraft Cylinders Are Reliable
Being that you can’t simply pull your airplane over and take a look at the engine in midair, you want reliable cylinders, right? Luckily, aircraft cylinders are known for reliability.
John Goglia of AviationPros.com stated in a 2014 article that engines are much improved today compared to the 1960s and 70s engines. He goes on to say:
“Today’s young mechanics are unlikely to have to worry about changing cylinders — or any of a number of other jobs we used to do routinely, like adding oil because the engines consumed so much and leaked so badly. On a typical flight across the country from the east to west coasts, it was not unusual to add 10 or more gallons of oil per engine.”
The biggest improvement from previous decades has been noted in the lubricants being used. Today’s synthetic blend or fully synthetic oil greatly reduce friction thus giving a much better coating, reducing engine wear as well as keeping operating temperatures lower.
Aircraft Cylinders Have a High Power Output
Who doesn’t love a good amount of horsepower?
But, do you really understand horsepower? When applied to reciprocating engines, like we have been discussing, the engine must be running at a certain speed to be producing the amount of horsepower it is said to produce.
The major difference between automobile and aircraft power output is the length of time the engine can create this power output. Aircraft engines can create a power output for much longer durations than an automobile, typically around 2000 consecutive hours. If you attempted running a car for this type of power output for this length of time, you might as well call a tow truck and get your vehicle ready for the local trash dump.
So, You Want to Turbocharge It…
Superchargers, or turbochargers, can give a good amount of torque at all engine speeds to your aircraft. This is accomplished by increasing the density of the fuel/air charge that is delivered to the cylinders. The compressor that does this is typically a centrifugal impeller which is driven by a gas turbine that takes the gas that would be wasted and uses it to create more power for the engine.
So, put simply, air is compressed before the fuel is injected. The more tightly packed air compressed into the aircraft cylinders, the more fuel that can be added creating more mechanical power and an improved combustion process.
Although turbocharging sounds great, it does have a downside as well. This increase of power can increase the sea level rated power but this also limits the full power at lower altitudes due to engine temperature limitations.
Another downside is that turbocharging allows your aircraft to maintain its rated power only up to the critical altitude which typically happens around 6000-7000 feet, and then the rating will begin to decrease.
By understanding the way your aircraft works you can begin to problem solve on your own. This type of mental training is what will keep you flying safely throughout your career!
We hope this article has given you a better grasp on the mechanics of your aircraft and how aircraft cylinders work. If you found this article helpful, please share it with your friends by using our social media buttons!