The Piston Engine EO M232.02 1x60 w/ FSgt Aikens

Importance Why are we learning this? The book says that it’s to “develop an understanding of subsequent and related principles” Which is not very helpful at all... Why do you think we’re learning this? (Other than for your level test)

Importance As you may imagine, engines are somewhat important in the aviation industry, being the provider of one of the 4 main forces of flight. Piston engines are the most popular in the general aviation community. Chances are, if you are flying a powered aircraft in the next ten years, it will be a piston powered aircraft. Piston engines are also common in other places, like cars and boats. This information can become quite handy when you need it.

Engine Parts There are many parts to the modern aircraft engine, but for the sake of this class, we’ll only be focusing on the basic 87 parts. That’s a joke

Engine Parts Cylinder: The main component, this is the base for the piston, and where combustion takes place. Easily Spotted by it’s cylinder shape

Engine Parts Piston: A metal arm in the cylinder driven up and down by exploding air and fuel, capturing the explosive force.

Engine Parts Connecting Rod: Connects the piston to the crankshaft, and transfers the up and down motion into rotation

Engine Parts Crankshaft: The spinning part in the middle Also used to connect the power of multiple pistons, This is where the power is transferred into a useable force Pistons Cylinders Crankshaft

Engine Parts Camshaft: a second rod driven by the crankshaft with bumps- or cams that control the opening and closing of valves for each cylinder.

Engine Parts Camshaft: SOHC: Single overhead camshaft DOHC: Dual overhead camshaft

Engine Parts Distributor: A device that times the spark plugs to fire in sequence (The spark plugs are the part that ignite the mixture in the cylinder, with a spark)

Engine Parts Carburetor: When air enters the engine, it passes through the carburetor where it is mixed with fuel droplets. The mixture then enters the cylinders.

Engine Parts Oil Sump: The engine needs oil for lubrication, flushing, sealing, and cooling. The sump is like a collector pan under the engine. Wet Sump: The oil is kept at the bottom and the connecting rods ‘splash’ in the oil. Dry Sump: The oil is pumped through the engine via tubes and pipes.

Review What’s a cylinder (when referring to engines)? The cylinder is the central block where combustion takes place. What is a crankshaft? The crankshaft is the connector between cylinders and outputs engine power. What part converts the up and down movement of the piston into circular motion? The connector rod

I’d suggest you make a chart for this next section. Engine type Advantages Disadvantages Important Facts

Engine Configurations There are several ways that we can arrange the pistons, we do this for a few reasons... More power! Changing the shape of the engine Adding more pistons (More power!) Or for better weight distribution

Engine Configurations Rotary Piston: (Not to be confused with Rotary, or Radial) In a Rotary Piston engine, the pistons are arranged radially (that means in a circle) around a central driveshaft. The drive shaft remains fixed, and the entire engine spins around it. A historical engine, not used after the first world war, and commonly seen in museums. Disadvantages: Poor visibility, not very aerodynamic, and the aircraft will tend to turn in one direction better than the other, making flying difficult. But it was the best we had at the time

Engine Configurations Radial Engine In a radial engine, pistons are arranged in a circle around a single point. The pistons remain fixed, compared to the rotary engine. Advantages: Good power output, and relatively easy maintenance. We can also stack engines for more power. Disadvantages: Not very aerodynamic, poor visibility, and very loud. The radial engine is sometime still seen today on older aircraft.

Engine Configurations Inline: On an Inline engine, all the cylinders are arranged in a line. Advantages: Thinner than a radial engine, relatively simple. Disadvantages: Still blocks forward visibility, adding cylinders makes for more power, but anymore than 6 cylinders will start to cause shaking and warping. Because of that, it’s mostly used only in small airplanes,

Engine Configurations Inline V, H, X, W....: An inline engine coupled at the crankshaft with another inline engine at various angles to produce the shape of a letter. Advantages: Very good power for size Disadvantages: Still not great visibility over the nose. In this example this pilot cannot see directly in front of him over the nose.

Engine Configurations Horizontally Opposed (Inline-O): Similar to Inline V, but with a 180 degree angle between the banks of cylinders. Advantages: All the power of a two bank inline engine, but flattened for space saving and better forward visibility. Disadvantages? This is the most common type of piston engine in general aviation.

Confirmation What kind of engine was primarily used in the first world war? Rotary Piston What engine part controls valve timing? Camshaft What engine fluid is associated with a sump? Oil What engine configuration provides the best visibility? Horizontally Opposed (Inline-O) In what part does combustion take place? Cylinders If the cylinders are mounted in a circle, but they don’t move, what is the configuration? Radial

Confirmation Lets look at some engines and describe the configuration. Inline W Inline O, or Horizontally Opposed Radial, or Rotary (you can’t tell in the picture)

End of lesson That was EO M232.02 In your next engines class we’ll learn about the operation of these engines and the stroke cycle.

Extra If you wanted to build a big multi engined aircraft, what engine would you use? (answers may vary) What considerations would you take flying a rotary piston aircraft? (The aircraft will tend to pull to the direction of rotation) Why are stacked radial engines so rare today? (They were replaced by gas turbine engines) Why do carburetors ice up? (The venturi cools down the air to below freezing) How do we get more power with the same number of cylinders? (Bigger cylinders/more fuel) The Wankel rotary pistonless engine