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Regional Gliding School Types of Reciprocating Engines QThere are three main types of piston engines in current use: –Horizontally Opposed –Radial –In-Line.

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Presentation on theme: "Regional Gliding School Types of Reciprocating Engines QThere are three main types of piston engines in current use: –Horizontally Opposed –Radial –In-Line."— Presentation transcript:

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3 Regional Gliding School Types of Reciprocating Engines QThere are three main types of piston engines in current use: –Horizontally Opposed –Radial –In-Line

4 Regional Gliding School Horizontally Opposed Two banks of cylinders which lie directly opposite to each other in the horizontal plane. Four, six or eight cylinders. Design is flat with small frontal area (good visibility) and low drag production. Most commonly used in general aviation.

5 Regional Gliding School Radial Cylinders arranged radially. Always an odd number of cylinders. Crankshaft is short, compact and light. Produces tremendous horsepower. Poor shape increases parasite drag and reduces forward visibility.

6 Regional Gliding School In-Line Cylinders are arranged side by side in a row. Practical limit is six. Any more cylinders and V, X or H-type in-line engines are used. Two crankshafts side by side. Some are inverted for better visibility. Little drag but heavier engine and size limited.

7 Confirmation Stage NOTE: You must use the buttons in the Confirmation Stage

8 Regional Gliding School Aero Engines Basic construction and the four stroke cycle A B C D Radial In Line Horizontally Opposed V6 Let's try a few review questions on Aero Engines: Question #1 - What type of engine is the most commonly used in general aviation?

9 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

10 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

11 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

12 That answer is correct. Let's move on...

13 Regional Gliding School Aero Engines Basic construction and the four stroke cycle A B C D Poor visibility Short crankshaft Size is limited Let's try a few review questions on Aero Engines: Question #2 - What is an disadvantage of using a radial engine? Heavy crankshaft

14 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

15 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

16 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

17 That answer is correct. Let's move on...

18 Regional Gliding School Construction of a Reciprocating Engine Piston - Cylinder shaped object that moves up and down. Piston Rings - wrap around the piston and provide a seal between the piston and cylinder. Connecting Rod - joins the piston to the crankshaft, which turns the propeller. Cylinder Head - contains the inlet (intake) valve, exhaust valve and two spark plugs.

19 Regional Gliding School Construction of a Reciprocating Engine Camshaft - turned by the crankshaft and operates the push rods and rocker arms. It turns at half the speed the crankshaft turns. Magnetos - provide electrical current to ignite the Fuel/Air mixture through the distributor. Intake Valve Ports - allow air to enter the cylinder and is connected to the carburetor where the air and fuel are mixed. Exhaust Valve - connected to the exhaust pipe, which vents the exhaust fumes away from the cabin.

20 Regional Gliding School Piston Spark Plugs Cylinder Intake Valve Exhaust Valve Connecting Rod Crankshaft Major Engine Components

21 Regional Gliding School The Four Stroke Cycle  Most piston engines operate on the four stroke cycle.  The piston moves through four strokes, two up and two down, to complete the cycle.  The crankshaft makes two complete revolutions.  The four strokes are:  the induction (or intake) stroke,  the compression stroke,  the power (or combustion) stroke, and  the exhaust stroke.

22 Regional Gliding School The Induction (or Intake) Stroke ÜIntake valve is open. ÜPiston moves down. ÜFuel/air mixture drawn into combustion chamber through intake valve. ÜExhaust valve remains closed.

23 Regional Gliding School The Compression Stroke  Both valves are closed.  Piston moves up.  Mixture is compressed.  Compression ratio is comparison of volume of mixture with piston at the bottom and volume with piston at the top.

24 Regional Gliding School The Power (or Combustion) Stroke  Both valves are closed.  Compressed mixture is ignited by spark plug.  Burning gas expands forcing piston down.  Energy drives other three strokes as well as useful work (i.e.. turn propeller).

25 Regional Gliding School The Exhaust Stroke  Exhaust valve is open.  Piston moves up.  Burnt gas is pushed out through exhaust valve.  Intake valve remains closed.

26 Regional Gliding School Timing  The purpose of timing is to improve the performance of the engine.  Valves take time to open and close.  Therefore they are timed to open early and close late in order not to waste any of the induction or exhaust stroke.

27 Regional Gliding School  Timing the valve to open early.  Timing the valve to close late.  Allowing both valves to remain open at the same time. Valve Lead Valve Lag Valve Overlap

28 Regional Gliding School Valve Clearances  Valve clearance, or tappet clearance, is a space that must be provided between the valve stem and rocker to allow for heat expansion of the metal.  Clearances too wide cause a loss of power and excessive wear.  Clearances too close can warp the valves.

29 Confirmation Stage NOTE: You must use the buttons in the Confirmation Stage

30 Regional Gliding School Aero Engines Basic construction and the four stroke cycle A B C D Power Compression Exhaust Let's try a few review questions on Aero Engines: Question #3 - Name the second stroke in the four stroke engine? Intake

31 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

32 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

33 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

34 That answer is correct. Let's move on...

35 Regional Gliding School Aero Engines Basic construction and the four stroke cycle A B C D Power Compression Exhaust Let's try a few review questions on Aero Engines: Question #4 - During which stroke do the spark plugs fire? Intake

36 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

37 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

38 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

39 That answer is correct. Let's move on...

40 Regional Gliding School Aero Engines Basic construction and the four stroke cycle A B C D Valve closes late Both valves remain open Both valves remain closed Let's try a few review questions on Aero Engines: Question #5 - What is the definition of valve lag? Valve closes early

41 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

42 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

43 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

44 That answer is correct. Let's move on...

45 Regional Gliding School Congratulations!! You have now completed the Basic Construction and the Four Stroke Cycle lesson of the Aero Engines Module. Of course, this lesson is always available to you for future reference if required. You are now ready to move along to the next Aero Engines lesson you have not completed or to any other module you wish. You can advance to the Self Test Module if you feel ready to challenge the final exam. Good Luck! Aero Engines Basic construction and the four stroke cycle


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