Cylinder Bank

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Merlin Engine Cylinders

This is a bank of six cylinders from a Merlin engine. Air and fuel are burnt inside the cylinders to move the pistons up and down. A crankshaft converts the up-and down-motion of the pistons into a round-and-round motion, turning a shaft connected to the propeller.

The ‘four-stroke’ cycle:

  1. The piston moves to the bottom of the cylinder. The exhaust valves close and the inlet valves open, letting in a mixture of air and fuel.

  2. All the valves close. The piston moves back up and compresses the air and fuel at the top of the cylinder.

  3. The sparkplug ignites the compressed air and fuel. The explosive force pushes the piston down. This is the power stroke.

  4. The exhaust valves open. The piston moves up and pushes out the exhaust gases, The cycle can now begin again.
Four-stroke cycle diagram from Air Publication 3048, Standard Technical Training Notes: Flight Mechanics (Engine), March 1944.

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