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TRANSPORTATION

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

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TRANSPORTATION

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  1. TRANSPORTATION

  2. 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

  3. 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

  4. 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

  5. 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 --- 3rd 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

  6. Space Transportation • The world entered space age in 1957 --- 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

  7. 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

  8. 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

  9. 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

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