TRANSPORTATION

Inter-modal Transportation –Goods moved over long distances often travel on several different kinds of transportation systems; trailer, truck, railroad car, ship –The freight does not have to be unloaded along the way –The ships used are called container ships –The carrying of tractor trailer by trains is called piggyback –An inter-modal system is so reliable that it is often used to supply parts for “just-in time” manufacturing

Air Transportation –Chinese sailors would tie a person to a kite and try to fly it  Lighter-Than-Air Vehicles (LTA) –Two Frenchmen built a hot-air balloon in 1783 that could carry people –Objects in water have buoyancy while that in air have lift –Lift: An upward force equal to the weight of the air displaced by the object –Hot air, hydrogen or helium are lighter than air (LTA) –In early 1900s, huge LTA ships called dirigibles carried passengers and cargo around the world --- filled with hydrogen –Today, LTA ships called blimps use helium gas. They are used advertising, cargo lifting and as platforms for cameras –Passive lift: lift because of volume and weight –Active lift: lift by the movement through the air --- powered flight

Air Transportation  Active-Lift Aircraft –The first powered flight was made by Orville Wright in 1903 –Orville and Wilbur added a 12 hp engine driving two propellers, to a glider (unpowered plane) –Passenger service started in United States in 1914 –World War II brought many changes  Airplanes were mass-produced  Airframe and electronics were improved  Military planes started using jet engines after World War II –The first person to fly faster than the speed of sound was Chuck Yeager –Mach 1 is the speed of sound. Mach 2 is twice the speed of sound –Once the plane goes faster than M1, it is easier to control --- shock –Jumbo jets carry hundreds of people at a time over long distances –The British and French Concorde carries passengers at twice the speed of sound –Military planes carry large cargoes and refuel in-flight

Air Transportation  How Planes Fly –Four forces: Weight, Lift, Drag and Thrust –Bernoulli’s Principle: As air flows over a surface, its pressure decreases in places where the air speed increases –The curve at the top of the wing makes the air, over the top, faster than under the bottom  Aircraft Engines –Internal combustion engines that turn propellers to provide thrust --- air movement from front to back –Propeller are mounted on the wing (1) a pusher --- at the back, (2) a puller --- at the front –In a jet engine, a compressor forces air into a combustion chamber –The burning mixture of air, fuel expands and rushes out rd Law –The burning gas also turns a turbine --- generators –In a turbo-prop engine, the turbine drives a propeller –A rocket takes its own oxygen

Space Transportation –The world entered space age in Sputnik --- circled the earth every 90 min –Yuri Gagarin of USSR made the first manned flight in 1961 –Neil Armstron and Edwin Aldrin were the first to set foot on the moon –To reach orbit, a speed of more than 17,000 miles per hour must be reached –An additional thrust is needed to accelerate the vehicle to 25,000 miles per hour, the speed needed to escape earth orbit –Space travel poses many problems  Carry own air  Weightless --- how to perform normal chores  Greatest distances, longest times --- Voyager took 12 years to travel from the earth to Neptune

Transportation Safety –In 1912, the largest steam ship, Titanic hit an iceberg on her first voyage –Most vehicles are designed with features such as air bags and improved bumpers –It is estimated that 17,000 fewer people would die in traffic accidents each year if people used seat belts

Nonvehicle Transportation Systems –They move materials and people without vehicles  Pipelines –Used to move crude oil or natural gas –They extend from the resources to the place where fuels are refined or loaded abroad  Conveyors –Parts are moved in most assembly lines, from work station to work station by conveyors –Coal and electronic parts are often moved this way

People Movers –Escalators, elevators and personal rapid transit systems (PRTs) –Elisha Otis invented freight elevators –PRTs move people horizontally from one place to another --- airport –Elevators and PRTs use vehicles, escalators and moving sidewalks do not –Escalators can move people a little more quickly than walking or climbing stairs