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Conestoga Valley High SchoolAviation Technology
PowerplantEngines
Aircraft Engines
• Two common types– Reciprocating (Piston)– Turbine (Turbofan or turboprops)
• Additional Engine Types– Ramjet– Scrams– Rockets
1903- 1940s: Propeller & Piston Era
• From 1903 (Wright bros.) until the Early 1940s, all aircraft used the reciprocating engine combined with a propeller as their propulsion system.
Reciprocating engine or internal combustion is similar to a car engine.– A propeller is essentially a
type of fan which transmits power by converting rotational motion into thrust to propel the aircraft (move forward).
Reciprocating engines use the energy produced by burning a mixture of air and fuel to drive
the propeller.
History of the IC Engine
• 1820-1900 Advancements• First Patent 1826:
American Samuel Morey• First gas IC on a wheeled
vehicle 1862: Frenchmen Alphonse deRochas
• Four-stroke engine patented 1876: German Nikolaus Otto (Otto Cycle)
• First “modern” gasoline engine patent 1887: German Gottlieb Daimler
Otto
Daimler
Reciprocating Engine Parts
• Basic Parts– Cylinder– Pistons– Connecting Rod– Crankshaft– Valves– Spark Plugs– Valve-operating
Mechanism (CAM)
DEFINITIONS
TDCTop Dead CenterPiston at top of
stroke.
BDCBottom Dead CenterPiston at Bottom of
stroke.
STROKETDC to BDCBDC to TDC180 degrees of
crankshaft rotation
FOUR CYCLE (Stroke)4 x 180 = 720 degrees
to make one complete cycle.
Reciprocating Engine Operating Principles
• Intake– As the piston moves
down from the top of the cylinder the intake valve opens & a mixture of air/fuel is drawn into the cylinder.
• Compression– The intake valve closes
when the piston is at the bottom of the cylinder. It moves back up the cylinder & compresses the air/fuel mixture.
Reciprocating Engine Operating Principles
• Ignition & Power– As the compressed
air/fuel mixture is compressed the spark plug ignites the mixture which creates an explosion and pushes the piston back down.
• Exhaust– When the piston
reaches BDC & starts back up the cylinder the exhaust and heat of the ignition is released from the exhaust valve.
4 Stroke Reciprocating Engine
INTAKE COMPRESSION POWER EXHAUST
Engine Cycles
Cylinder Arrangements
• Most Common four cylinder arrangements
• In-Line• “V” In-Line• Horizontally
Opposed In-Line• Radial
Measuring Power/Thrust
• An engines power is measured in horsepower
• One horsepower equals 33,000 foot-pounds of work per minute
• Speed is measured in Knots• d• 1 knot =1.15 mph
Review Questions
•What type of engine was the most common for planes up until the 1940’s?
•Who invented the 4 stoke engine which is still in use today?
•What are the 4 basic operating principles of a 4 stroke engine?
Reciprocating or Piston
Intake, Compression, Power, Exhaust
Nikolaus Otto