Module 16 Piston Engine 100 Important Sentences for Revision

 1. Basic Engine Principles

1. A piston engine converts chemical energy into mechanical power.
2. It works on the Otto cycle for spark ignition engines.
3. The four strokes are intake, compression, power, and exhaust.
4. In the intake stroke, the piston moves down drawing in air-fuel mixture.
5. In the compression stroke, the mixture is compressed.
6. The spark plug ignites the mixture near top dead center.
7. The power stroke forces the piston down.
8. The exhaust stroke expels burnt gases.
9. The crankshaft converts linear motion to rotary motion.
10. Engine power depends on displacement and compression ratio.

2. Engine Construction

11. The cylinder head contains valves and spark plugs.
12. The cylinder barrel guides piston movement.
13. The piston transfers gas pressure to the connecting rod.
14. The connecting rod links the piston to the crankshaft.
15. The crankshaft converts reciprocating motion into rotation.
16. Bearings support rotating parts and reduce friction.
17. The camshaft controls valve timing.
18. Pushrods and rocker arms open and close valves.
19. Valve springs ensure proper valve seating.
20. The crankcase houses and supports all major components.

3. Engine Types and Configurations

21. Engines may be inline, opposed, radial, or V-type.
22. Opposed engines are common in light aircraft.
23. Radial engines have cylinders arranged around a crankcase.
24. V-type engines have two banks of cylinders forming a “V” shape.
25. Inline engines are compact and used in smaller aircraft.
26. Radial engines offer good cooling and power-to-weight ratio.
27. Opposed engines are smooth and balanced in operation.
28. Multibank engines improve power output.
29. Turbocharged engines use exhaust gases to increase power.
30. Supercharged engines use mechanical compressors for power boost.

4. Engine Operating Cycles

31. A two-stroke engine completes one cycle in two strokes.
32. A four-stroke engine completes one cycle in four strokes.
33. Four-stroke engines are more fuel-efficient.
34. Two-stroke engines are lighter and simpler.
35. Compression ratio affects efficiency and power.
36. Higher compression ratios increase performance.
37. Detonation occurs when mixture burns uncontrollably.
38. Pre-ignition happens before spark ignition.
39. Both detonation and pre-ignition can damage the engine.
40. Proper fuel grade prevents detonation.

5. Induction and Fuel Systems

41. The induction system delivers air or fuel-air mixture to cylinders.
42. The carburetor mixes air and fuel in correct proportion.
43. Mixture control adjusts fuel flow for altitude changes.
44. Float-type carburetors are common in piston aircraft.
45. Pressure carburetors prevent icing and fuel starvation.
46. Fuel-injection systems deliver fuel directly into intake ports.
47. Fuel injection provides better fuel distribution.
48. Turbochargers use exhaust gases to drive a compressor.
49. Superchargers are driven mechanically by the engine.
50. Induction icing can occur in moist, cold conditions.

6. Ignition System

51. The ignition system provides spark for combustion.
52. Each cylinder has two spark plugs for redundancy.
53. Magnetos generate electrical energy independently.
54. Dual ignition improves reliability and efficiency.
55. The magneto uses rotating magnets to induce current.
56. The distributor sends high voltage to each spark plug.
57. Ignition timing affects engine performance.
58. Early timing can cause knocking.
59. Late timing reduces power and increases heat.
60. Spark plug fouling occurs from lead or carbon deposits.

7. Lubrication System

61. The lubrication system reduces friction and cools parts.
62. Piston engines use either dry sump or wet sump lubrication.
63. In a dry sump, oil is stored in an external tank.
64. Scavenge pumps return oil from the crankcase to the tank.
65. Wet sump systems store oil in the crankcase.
66. Oil coolers maintain correct operating temperature.
67. Filters remove dirt and metal particles.
68. Pressure relief valves prevent excessive oil pressure.
69. Oil viscosity affects flow and lubrication quality.
70. Regular oil checks ensure safe operation.

8. Cooling System

71. Air-cooled engines use fins to dissipate heat.
72. Liquid-cooled engines use coolant circulated through jackets.
73. Baffles direct airflow around cylinders in air-cooled engines.
74. Overheating can cause detonation or piston seizure.
75. Cooling is essential for maintaining performance.
76. Cylinder head temperature is a key indication of cooling efficiency.
77. Oil also assists in cooling internal parts.
78. Proper cowling ensures efficient airflow.
79. Temperature gauges monitor engine heat levels.
80. Poor cooling reduces engine life.

9. Exhaust and Supercharging

81. The exhaust system removes combustion gases.
82. Exhaust manifolds collect gases from cylinders.
83. Mufflers reduce noise and back pressure.
84. Turbochargers increase intake air pressure.
85. Wastegates control turbocharger boost pressure.
86. Superchargers use engine power to compress intake air.
87. Boost pressure must be controlled to prevent damage.
88. Exhaust gas temperature indicates engine performance.
89. Turbo lag occurs due to delayed response of the turbine.
90. Proper maintenance prevents cracks in exhaust systems.

10. Engine Operation and Maintenance

91. Engine start requires correct fuel mixture and ignition.
92. Warm-up allows oil to circulate before high power use.
93. Lean mixture improves fuel economy in cruise.
94. Rich mixture provides cooling during high power.
95. Power checks verify engine performance before flight.
96. Vibration indicates imbalance or misfire.
97. Compression testing checks cylinder sealing.
98. Spark plug inspection ensures proper ignition.
99. Engine overhaul restores components to serviceable condition.
100. Proper operation and maintenance ensure reliability and safety.

 

Read More