Flight Power

Warm-Up Questions CPS Questions 1-2 Chapter 1, Lesson 5

Lesson Overview The principles of Boyle’s Law, Charles’s Law, and Gay-Lussac’s Law The characteristics of internal combustion engines The mechanical, cooling, and ignition systems of reciprocating engines Chapter 1, Lesson 5

Lesson Overview, cont. How the different types of jet engines work The role of reversers and suppressors used in jet aircraft Reaction engines The development of new engine technology Chapter 1, Lesson 5

(Note to teacher: Use “Pick a Student” button in CPS) Quick Write Which is the more significant achievement – being the first to invent something, or the first to make it practical? Or are both equally important? (Note to teacher: Use “Pick a Student” button in CPS) Chapter 1, Lesson 5 © Laser143/Dreamstime.com

Boyle’s Law Relationship between pressure and volume of a confined gas at a constant temperature When pressure increased, the volume decreased, when pressure decreased, the volume increased Chapter 1, Lesson 5 Reproduced from NASA/Glenn Research Center

Charles’s Law The volume of a gas is directly proportional to its temperature If temperature of a gas rises, its volume increases; if temperature falls, the volume decreases Chapter 1, Lesson 5 Reproduced from NASA/Glen Research Center

Gay Lussac’s Law Relationship between pressure of a gas, and temperature, when the volume is constant Pressure rises when temperature rises, and pressure falls when temperature falls Chapter 1, Lesson 5 Reproduced from NASA/Glen Research Center

Activity 1: Animated Gas Lab   View the Animated Gas Lab at the NASA website Use the lab to work through the questions Chapter 1, Lesson 5

The Characteristics of Internal Combustion Engines Internal combustion engines turn propellers which generate thrust Combustion process— chemical energy converts to mechanical energy The piston compresses fuel and air before combustion; then is forced back down the cylinder following combustion Chapter 1, Lesson 5 Reproduced from NASA/Glen Research Center

Learning Check Questions CPS Questions 3-4 Chapter 1, Lesson 5

Activity 2: Internal Combustion Engine Parts   Observe the four-stroke internal combustion engine animation  Label the engine parts and provide a short description Chapter 1, Lesson 5

Activity 2—Four Stroke Internal Combustion Engine Chapter 1, Lesson 5 Reproduced from NASA/Glen Research Center

Reciprocating Engines Internal combustion engine is a reciprocating engine Back-and-forth movement of the pistons produces mechanical energy Most small aircraft have reciprocating engines Parts include cylinders, pistons, connecting rods, a crankshaft, crankcase, intake and exhaust valves, and spark plugs Chapter 1, Lesson 5 Reproduced from US Department of Transportation/Federal Aviation Administration

Intake Stroke—First Stroke Piston moves down, intake valve opens, drawing air and fuel in at constant pressure Provides great deal of surface area that reacts quickly with the oxygen in the air Chapter 1, Lesson 5 Reproduced from NASA/Johnson Space Center

Compression Stroke— Second Stroke The piston reaches the bottom, the intake valve closes, sealing the cylinder Volume decreases, the piston compresses the fuel-air mixture, raising temperature and increasing pressure Gas particles are close together, can react quickly when ignited Chapter 1, Lesson 5 Reproduced from NASA/Johnson Space Center

Power or Ignition Stroke— Third Stroke As the piston nears the top, a surge of current is sent to spark plug The Spark ignites the compressed fuel- air mixture Fuel rapidly combines with oxygen and produces carbon dioxide gas and water vapor Hot gases force the piston down turning the crankshaft The crankshaft turns the aircraft propeller Chapter 1, Lesson 5 Reproduced from NASA/Johnson Space Center

Exhaust Stroke— Fourth Stroke Piston reaches the bottom and starts back up the cylinder, the exhaust stroke begins The exhaust valve opens, residual heat is released, and pressure returns to atmospheric conditions The piston pushes waste gas out of the cylinder Chapter 1, Lesson 5 Reproduced from NASA/Johnson Space Center

Cooling   Air cooled system—air flows through openings at the front of the engine cowling into the engine compartment Hot air leaves the engine through openings in lower, aft portion of the cowling Liquid-cooled —requires the additional weight of a radiator and liquid Radiators pump air-cooled liquid in pipes around hot parts of an engine Chapter 1, Lesson 5 Reproduced from US Department of Transportation/Federal Aviation Administration

Ignition System Provides the spark that ignites the fuel-air mixture in cylinders Firing of two spark plugs improves combustion and results in more power; if one magneto fails, other can still work on its own Chapter 1, Lesson 5 Reproduced from NASA/Glen Research Center

Learning Check Questions CPS Questions 5-6 Chapter 1, Lesson 5

Turbojets Engine is an open tube that burns fuel continuously Main parts: compressor, combustion chamber, turbine, inlet, shaft, and nozzle Large air mass enters the inlet and is drawn into a rotating compressor Chapter 1, Lesson 5 Reproduced from US Department of Transportation/Federal Aviation Administration

Turbojets, cont. Compressor raises air pressure and forces the gas into smaller volumes, gas pressure increases and heats up Fuel is injected into the combustion chamber, where it ignites Heated gas passes over turbine blades causing them to rotate shaft connected to compressor Nozzle’s purpose is to convert chemical energy into mechanical energy, thus producing thrust Chapter 1, Lesson 5

Turbofans Modified turbojet engine - has additional turbine to turn a fan at front of the engine Two-spool engine; one powers compressor, other turns the large fan Air from large fan enters the engine core, where fuel burns to provide some thrust 90 percent of the air bypasses the engine core; as much as 75 percent of the total thrust is from bypass air Chapter 1, Lesson 5 Reproduced from US Department of Transportation/Federal Aviation Administration

Turboprops Hybrid of a turbojet and a propeller engine Has a turbojet core to produce power but with two turbines First turbine powers the compressor; the second turbine powers the propeller Chapter 1, Lesson 5 Reproduced from US Department of Transportation/Federal Aviation Administration

Ramjets Ramjets work with another power source for initial thrust, such as a rocket Operates by combusting fuel in a stream of air compressed by aircraft’s forward motion Airflow is subsonic, less than the speed of sound Chapter 1, Lesson 5 Reproduced from NASA/Johnson Space Center

Scramjets Scramjets overcome the speed limitation It is a supersonic- combustion ramjet Needs another engine or vehicle to accelerate it to operating speed Chapter 1, Lesson 5 Reproduced from NASA's Dryden Flight Research Center

Thrust Reversers Diverts thrust to the opposite direction of the aircraft’s motion Clamshell reverser forms a shield at the back of the nozzle, deflects exhaust so it no longer produces forward thrust Cascade reverser is a series of airfoils with a high degree of camber that opens, to change the airflow’s direction Chapter 1, Lesson 5 Courtesy of Dan Brownlee

Noise Suppressors Laws regulate how much noise an aircraft can make Flow of exhaust creates much of the racket Chevron noise suppressor has teeth cut in nozzle’s edge to reduce noise Corrugated noise suppressor has ridged nozzles; breaks noise in a large exhaust flow Ejector-type noise suppressor directs surrounding air so it mixes with the high- velocity exhaust to reduce noise Chapter 1, Lesson 5 Copyright © Boeing. All Rights Reserved

Learning Check Questions CPS Questions 7-8 Chapter 1, Lesson 5

Activity 3: Jet Engine Characteristics View the various animations of a jet engine to observe the parts and their functions Label the parts and provide a short description of characteristic Chapter 1, Lesson 5

Activity 3: Engine Chapter 1, Lesson 5 Reproduced from NASA/Glen Research Center

Activity 3: Compressor Chapter 1, Lesson 5 Reproduced from NASA/Glen Research Center

Activity 3: Turbine Chapter 1, Lesson 5 Reproduced from NASA/Glen Research Center

Reaction Engines Reaction engine develops thrust by its reaction to a substance ejected from it Operates according to Newton’s third law of motion Rocket engines are also reaction engines Chapter 1, Lesson 5 Courtesy of NASA

The Development of New Engine Technology Aerospace engineers are working on new engine technologies that cut fuel use and reduce emissions Geared turbofan engine reduces fuel consumption, emissions, engine noise, and operating costs Open rotor jet engine focuses on fuel efficiency, reduced emissions, and noise reduction Chapter 1, Lesson 5 Courtesy of NASA/Glenn Research Center

Thrust Vectoring Thrust vector engine has nozzles that turn to redirect thrust; lets aircraft maneuver with greater precision The aim of this technology is maneuverability, not fuel efficiency Chapter 1, Lesson 5 Courtesy of NASA/Glenn Research Center

Learning Check Questions CPS Questions 9-10 Chapter 1, Lesson 5

Activity 4: Flight Power Create a presentation on a jet engine (current model or one under development) Research sources and describe how the engine works, and why the engine is suited for the aircraft’s purpose Chapter 1, Lesson 5

Summary The principles of Boyle’s Law, Charles’s Law, and Gay-Lussac’s Law The characteristics of internal combustion engines The mechanical, cooling, and ignition systems of reciprocating engines Chapter 1, Lesson 5

Summary, cont. How the different types of jet engines work The role of reversers and suppressors used in jet aircraft Reaction engines The development of new engine technology Chapter 1, Lesson 5

Review Questions CPS Questions 11-12 Chapter 1, Lesson 5

Next…. Done – flight power Next – aviation innovation Chapter 1, Lesson 5 Copyright © Boeing. All Rights Reserved