FLIGHT POWER Know basic engine principles. 1. Define a list of terms related to basic engine principles. 2. Define Boyle’s Law and Charles’ and Gay- Lussac’s Law. 3. Describe how engines evolved from the earliest version to present day.

FLIGHT POWER Know basic engine principles. 4. Describe the mechanical, cooling, and ignition systems of the reciprocating engines. 5. Describe the role of reversers and suppressors used in jet aircraft. 6. Given real causes of pollution, state the method to eliminate the stated cause.

Overview Basic Engines Scientific Terms Reciprocating Engines Laws of Physics Jet Engines How Jet Engines Operate Types of Jet Engines Reversers and Suppressors Pollutants

Basic Engines History of Flight PowerHistory of Flight Power –Ancient pictures show evidence of the dream of flying on the walls of caves. –Through the use of engines, the dream of flight has been partially fulfilled. –Basic engines developed in three major stages. External combustion enginesExternal combustion engines Internal combustion enginesInternal combustion engines Gas turbine enginesGas turbine engines

Basic Engines External CombustionExternal Combustion –The development of the steam engine was the first successful harnessing of mechanical power for useful work. –A steam engine uses steam to change into motion the heat that is released by burning.

Thomas Savery External Combustion ãDeveloped the first steam engine in 1698 ãUsed hand-operated valves to let steam enter a sealed vessel or container

Thomas Newcomen External Combustion ãBuilt steam engine with piston inside cylinder ãCold water was sprayed into the cylinder and condensed the steam

James Watt External Combustion

ãInvented steam engine with two separate parts ãCylinder remained hot and condenser cool all the time James Watt

Henri Giffard External Combustion

Steam Engines External Combustion ãUsed today primarily in power plants

Internal Combustion

Gas Turbine Engines

Scientific Terms EnergyWorkHorsepowerThrust

Energy ãCapacity for doing work and overcoming resistance ãForce behind the movement of all things q Humans and animals use food as energy source

Energy ã Potential Energy (stored) ã Kinetic Energy (active)

Work ãExertion of a force over a given distance ãMeasured in foot-pounds W = F x D W = work F = force D = distance

Horsepower ãMeasures the output of engines ãJames Watt attached an apparatus to a horse and developed a formula to measure it James Watt

Horsepower number of foot- pounds of work seconds/minutes 550/33,000

Thrust ãPower of a jet engine is expressed in pounds of thrust Thrust = Weight of air x acceleration

Reciprocating Engines

Mechanical System ãCylinder ãPiston ãCrankshaft ãConnecting Rod ãValves

Mechanical System ãCylinder q Known as the engine’s combustion chamber q Where the power is developed

Mechanical System ãPiston q Fits snugly in the hollow cylinder allowing up-and-down linear (straight) motion q Fit will not allow air or fluid in the cylinder

Mechanical System Crankshaft The crankshaft and connecting rod allow for the movement of the propeller.

Mechanical System Connecting Rod Attached to the throws With the crankshaft, they change the direction of the pistons into a circular motion

Mechanical System Valves A rocker arm regulates the opening and closing of each valve. Lobes or rings on a camshaft push the rocker arm

Four-Stroke Cycle Stroke one is also called the intake stroke. The second step is the compression process. Near the end of the compression stroke, the air and fuel mixture is ignited by an electric spark from the spark plug. The fourth stroke is also called the exhaust stroke.

Four-Stroke Cycle - Stroke 1 Called intake stroke Piston moves down the cylinder creating vacuum Cam arrangement opens the intake valve Fuel and air drawn into the cylinder

Four-Stroke Cycle - Stroke 2 Piston moves up the cylinder Both valves closed Air and fuel compressed and pressure rises

Four-Stroke Cycle - Stroke 3 Air and fuel ignited by electrical spark Rise in temperature forces piston down

Four-Stroke Cycle - Stroke 4 Piston moves up forcing burned gas out of cylinder Burned gas transmitted to exhaust system

Four-Stroke Cycle Occurs at the same time in all cylinders, but not on the same step Ignition sequence of the cylinders called the firing order

Cooling System Engine produces vast amount of heat Modern aircraft engines use an air cooling system

Cooling System The liquid cooling system on an aircraft works the same as does the cooling system on most automobiles. The coolant flows through the engine block and around cylinders. The liquid circulates through a system of pipes to a radiator.

Ignition System Must receive an electrical spark originating in the magneto

Ignition System Compression Stroke Starter keeps rotating crankshaft Pistons move up and down Fuel and air mix in cylinder and compression begins Rotor spinsElectricity delivered from the magneto

Types of Reciprocating Engines ã How to get more horsepower from an engine? (1) Increase the number of cylinders or (2) Increase the size of each cylinder ã Attention focused on designs

Types of Reciprocating Engines In-line Engines Cylinders are located in a row, one behind the other Two classifications: Upright Inverted

Types of Reciprocating Engines Opposed Engines qTwo rows or banks of cylinders on each side of the crankshaft qRows directly opposite each other called horizontal opposed

Types of Reciprocating Engines V and X Engine “V” engine features two rows of cylinders set at an angle of about 45° The “X” engine is essentially an opposed “V” engine

Types of Reciprocating Engines Radial Engine Crankshaft with only one throw Odd number of cylinders in each bank or row Maximum number of cylinders in each bank is nine

Construction of Reciprocating Engines

Fuels Used in Reciprocating Engines Most common form of fuels is hydrocarbons derived from petroleum Gasoline and kerosene offer several advantages