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 Guided Tours of the BGA The Beginner's Guide to Aeronautics (BGA) was created as a Web-based "textbook." The creation of the BGA is a research project to explore the use of the personal computer and the Internet to present educational materials to students, teachers, and lifelong learners in a more interactive way than a printed, bound textbook. As a general rule, the Web consists of many individual pages that are connected, or related, to one another through hyperlinks. The Web is, therefore, much less structured than a bound book, in which one page follows another in a definite, numbered sequence. We have intentionally organized the BGA to mirror this unstructured approach. Users can navigate the pages of the BGA through hyperlinks based on their own interest and inquiry. For those who prefer more structure to the information available at the BGA, we have organized an alternative to the unstructured approach--a number of guided tours through the site. Each tour is organized around a single topic, and users move from page to page through the tour by using special buttons at the bottom of each page. Click to move back to the previous page. Click to move to the next page. Click to return to this page at the end of each tour. (Some pages will be "crossed" by more than one tour, so it is important to remember which tour you are on. If you click on a hyperlink you will leave the tour; you can rejoin the tour by using the browser's "Back" command. If you wish to abort a tour and return here, just click on the "Guided Tours" label located above the buttons. ) All of the tours begin and end on this page unless otherwise noted. Descriptions of each tour are given below--just click on the name of the tour to start you on your way. Have fun! Fundamentals Newton's Laws of Motion The motion of aircraft can be accurately described by the classical Laws of Motion developed by Sir Isaac Newton in the late 1600's. Forces, Torques, and Motion As an object moves through space it translates and rotates. The translations are in direct response to forces on the object. The rotations are in response to torques on the object. Thermodynamics Thermodynamics is the study of the effects of work, heat and energy on a system. There are three laws of thermodynamics based on large scale observations. Combustion Modern aircraft are powered by jet engines which produce thrust by burning a fuel. Combustion is the chemical process which combines fuel, oxygen, and a source of heat to produce heat and exhaust products. Basic Fluid Dynamics Equations The motion of any fluid can be described by the conservation of mass, momentum, and energy. Compressible Aerodynamics Additional forces are present when an object travels through a gas at speeds near or faster than the speed of sound for the gas. Shock waves may also be present in the flow field. Aircraft Weight Weight is a major design consideration for all aircraft. Equations have been developed to compute the aircraft's weight and center of gravity during design. Gases Standard Atmosphere Model The atmosphere is a thin layer of gas that separates the surface of the planet from outer space. The properties of the gas change with altitude through the atmosphere. Gas Statics The properties of a gas are related to one another. You can learn about the properties of a gas by considering a static volume of gas. Speed of Sound Small disturbances in a gas are transmitted at the speed of sound which depends on the temperature of the gas. The Mach number is the ratio of an object's speed to the speed of sound. Sound Waves Small disturbances in a gas are transmitted through the gas as spherical waves. If the source of the disturbance is moving the waves are distorted. Pitot Tube A Pitot Tube is a device for measuring the speed of an aircraft through the air. It depends on an application of Bernoulli's equation for a moving fluid. Wind Tunnels Wind Tunnels are large devices used to test models of proposed aircraft. (This tour does not return to this page) Powered Aircraft Forces on an Airplane There are four forces that act on an airplane. The motion of an aircraft depends on the relative magnitude of the forces. So you must first understand what the forces are, how they are directed, the nature of the forces, and how they are related. Cruising Aircraft If the four forces on an aircraft are perfectly balanced, the aircraft flies in a straight line at a constant speed. Equations have been developed which describe cruising flight. Into the Wind The aerodynamic forces on an airplane depend on the difference in velocity between the airplane and the air. Determining the forces and resulting motion is complicated by the wind. Parts of an Airplane Airplanes are composed of many parts with many different functions. Learn to recognize and identify the different parts of an airplane. Fuselage The fuselage (or body) of the airplane holds all of the parts together and carries the passengers or cargo. Jet Engines Most modern aircraft are powered by gas turbine, or jet engines. Wings The wings generate most of the lift necessary for flight. Ailerons Ailerons are parts of the wing which are used to roll the aircraft. Spoilers Spoilers are parts of the wing which are used to roll the aircraft and to decrease lift and increase drag during landings. Flaps and Slats Flaps and Slats are parts of the wing which are used during take off and landing to increase lift and drag. Elevators Elevators are control surfaces connected to the horizontal stabilizer and are used to pitch the aircraft. Stabilators Stabilators are control surfaces which provide both horizontal stability and pitch control for the aircraft. Rudder A Rudder is a control surface connected to the vertical stabilizer and used to yaw the aircraft. Control Surfaces On a modern aircraft, there are several moving parts which are used to control the motion of the aircraft. This tour examines these parts and the resulting motion. Gliders Forces on a Glider Gliders are unpowered aircraft. The forces on gliders and the response to external forces is quite similar to powered aircraft. Examples: paper airplanes and the Space Shuttle Gliding Flight Gliders are unpowered aircraft. The flight of a glider is a little easier to analyze than the flight of a powered aircraft Kites Forces on a Kite Kites are unpowered aircraft. They are very similar to gliders except that, instead of moving through air, a kite is held still and the blowing air moves past the kite. Kite Flying You can learn a great deal about aerodynamics by flying a kite. KiteModeler - Kite Simulator KiteModeler is an interactive computer program that lets you design and flight test a kite. Model Rockets Forces on a Model Rocket The forces on a model rocket are similar to forces on an aircraft although the thrust is used to overcome weight. Stability of a Model Rocket A model rocket relies on aerodynamics to provide stability during flight. Flight of a Model Rocket The flight of a model rocket depends on the relative size of the forces on the rocket. Parts of a Model Rocket Flying model rockets is a relatively safe and inexpensive way for students to learn about aerodynamics and propulsion. Model Rocket Engines Disposable solid rocket engines are used in model rockets. RocketModeler - Model Rocket Simulator RocketModeler is an interactive computer program that lets you design and flight test a model rocket. Other Flying Objects Falling Objects An object falling through the atmosphere is subjected to two forces, weight and drag, and attains a constant terminal velocity. If the object were falling in a vacuum, only gravity would act on the object. Objects that Generate Lift Many objects generate lift as they move through a fluid. CurveBall - Baseball Simulation A big league baseball player can throw a curveball because of aerodynamic forces on the ball. Investigate the forces on the ball by using this simulation program. Aircraft Lift Theories of Lift Lift is the force that keeps an aircraft flying. Many theories for the generation of lift have been proposed. Factors that Affect Lift Lift is the force that keeps an aircraft flying. There are many factors that affect the amount of lift generated by a body. Lift Equation Lift is the force that keeps an aircraft flying. There is a simple algebraic equation to relate the factors that affect lift. FoilSim - Lift Simulator FoilSim is an interactive computer program that lets you design a wing on-line and determine the theoretical lift of the wing. Aircraft Drag Sources of Drag Drag is the force that opposes the motion of an object through the air. There are several different sources of aircraft drag. Factors that Affect Drag Drag is the force that opposes an aircraft's motion. There are many factors that affect the amount of drag generated by a body. Drag Equation Drag is the force that opposes the aircraft's motion . There is a simple algebraic equation to relate the factors that affect drag. Aircraft Thrust Propulsion Systems Thrust is the force that pushes an airplane through the air. There are many different types of propulsion systems which generate thrust. Propellers For the forty years following the Wright Brothers first flight, aircraft used propellers to produce thrust. Modern general aviation aircraft still use propellers. Jet Engines Most modern aircraft are powered by gas turbine, or jet engines. There are several different types of jet engines which are used for different missions. Turbojets The turbojet is the most basic type of gas turbine engine. Afterburning Turbojets To develop the extra thrust needed for supersonic flight, an afterburner is often connected to the exit of a turbojet or turbofan engine. Turbofans Most modern airliners are powered by highly efficient turbofan engines. Turboprops Many small commuter airliners use highly efficient turboprop engines. The turboprop uses a gas turbine engine to turn a propeller. Ramjets A ramjet engine produces thrust by burning a fuel at high pressure and exhausting the gas through a nozzle. The high pressure is produced by the forward speed of the vehicle. Rockets A rocket engine produces thrust by burning a fuel at high pressure and exhausting the gas through a nozzle. The oxygen for combustion is carried with the propulsion system. Parts of a Jet Engine Jet Engines are composed of many parts with many different functions. Learn to recognize and identify the different parts of a jet engine. Inlet The inlet sits upstream of the compressor and brings air into the engine. Compressor The compressor increases the pressure of the air while delivering it to the burner. Combustor or Burner Combustion of the fuel takes place in the burner. Fuel is mixed with high pressure air from the compressor and burned. Power Turbine The power turbine sits downstream of the burner and extracts some energy from the hot exhaust to power the compressor. Nozzle The nozzle is a specially shaped tube which accelerates the hot exhaust gas to produce thrust. Thrust Equation Mathematical equations have been developed which describe the generation of aircraft thrust. Calculating Fuel Flow Rate Mathematical equations have been developed which describe the fuel usage of a jet engine. EngineSim - Engine Simulator EngineSim is an interactive computer program that lets you design a turbine engine on-line and determine the theoretical thrust, fuel flow, and weight of your engine. Aircraft Motion Basic Aircraft Motion The motion of an airplane through the air can be described as a combination of translation and rotation. Cruising Flight If the four forces on an aircraft are perfectly balanced, the aircraft flies in a straight line at a constant speed. Aircraft Roll Motion A roll motion is caused by deflecting the ailerons which causes the wings tips to move up and down. Aircraft Pitch Motion A pitch motion is caused by deflecting the elevators which causes the aircraft nose to move up and down. Aircraft Yaw Motion A yaw motion is caused by deflecting the rudder which causes the aircraft nose to move side to side. Banking Turns An airplane changes direction by rolling in the direction of the turn and producing a gradual curved flight path. Gradual Climb An airplane climbs whenever the lift is greater than the weight. The rate of climb is increased by high excess thrust. Simulation Programs FoilSim - Lift Simulator FoilSim is an interactive computer program that lets you design a wing on-line and determine the theoretical lift of the wing. EngineSim - Engine Simulator EngineSim is an interactive computer program that lets you design a turbine engine on-line and determine the theoretical thrust, fuel flow, and weight of your engine. CurveBall - Baseball Simulation A big league baseball player can throw a curveball because of aerodynamic forces on the ball. Investigate the forces on the ball by using this simulation program. RangeGames RangeGames is an interactive computer program that presents problems for you to solve. The problems involve aspects of cruising flight and aircraft take-off. RocketModeler - Model Rocket Simulator RocketModeler is an interactive computer program that lets you design and flight test a model rocket. KiteModeler - Kite Simulator KiteModeler is an interactive computer program that lets you design and flight test a kite. Interactive Atmosphere Model This interactive computer program lets you study how the properties of the atmosphere change with altitude. Interactive Sound Waves This interactive computer program lets you study how the doppler shift occurs and how shock waves are formed. Interactive Shock Waves This interactive computer program lets you study shock waves generated by supersonic flow passing a wedge. Interactive Isentropic Flow This interactive computer program lets you study isentropic supersonic flows. Interactive Nozzle Flow This interactive computer program lets you study how rocket and turbine engine nozzles operate. Navigation.. Beginner's Guide to Aerodynamics Beginner's Guide to Propulsion Beginner's Guide to Model Rockets Beginner's Guide to Kites Beginner's Guide to Aeronautics Back to top Go to... Beginner's Guide Home Page byTom Benson Please send suggestions/corrections to: benson@grc.nasa.gov