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