TRANSPORTATION

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TRANSPORTATION
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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

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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

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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

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Air Transportation

• How Planes Fly
• Four forces Weight, Lift, Drag and Thrust
• Bernoullis 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

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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

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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

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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

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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