Aircraft Engine Types And Construction

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Aircraft Engine Types And Construction
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The Heat Engine

• Converts chemical energy (fuel) into heat energy.
• Heat energy is then converted into mechanical
  energy.
• The heat energy is released at a point in the
  cycle where the pressure is high, relative to
  atmospheric.

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The Heat Engine

• Divided into groups or types depending upon
• The working fluid used.
• The means of compression.
• The Propulsive working fluid.

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Types Of Heat Engines
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Types Of Heat Engines

• Turbojet
• Means of compression Turbine-driven compressor
• Engine working fluid Fuel/air mixture
• Propulsive working fluid Fuel/air mixture

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Types Of Heat Engines

• Turboprop
• Means of compression Turbine-driven compressor
• Engine working fluid Fuel/air mixture
• Propulsive working fluid Ambient Air

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Types Of Heat Engines

• Ramjet
• Means of compression Ram compression
• Engine working fluid Fuel/air mixture
• Propulsive working fluid Fuel/air mixture

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Types Of Heat Engines

• Pulse-Jet
• Means of compression Compression due to
  combustion
• Engine working Fluid Fuel/air mixture
• Propulsive working Fluid Fuel/air mixture

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Types Of Heat Engines

• Rocket
• Means of compression Compression due to
  combustion
• Engine working fluid Oxidizer/fuel mixture
• Propulsive working fluid Oxidizer/fuel mixture

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Types Of Heat Engines

• Reciprocating
• Means of compression Reciprocating action of
  pistons
• Engine working fluid Fuel/air mixture
• Propulsive working fluid Ambient air

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Engine Requirements
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Engine Requirements

• Efficiency
• Power and Weight If the specific weight of an
  engine is decreased, the performance of the
  aircraft will increase.
• Reciprocating engines produce approximately 1 HP
  for each pound of weight.

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Engine Requirements

• Fuel Economy
• The basic parameter for describing the fuel
  economy of aircraft engines is specific fuel
  consumption.
• Specific fuel consumption for reciprocating
  engines is the fuel flow (lbs/hr) divided by
  brake horsepower.

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Engine Requirements

• Durability and Reliability
• Durability is the amount of engine life obtained
  while maintaining the desired reliability.
• Reliability and durability are built into the
  engine by the manufacture.
• Continued reliability is determined by the
  maintenance, overhaul, and operating personnel

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Engine Requirements

• Operating Flexibility
• The ability of an engine to run smoothly and give
  desired performance at all speeds from idling to
  full-power.
• The engine must also function efficiently through
  all variations in atmospheric conditions.

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Engine Requirements

• Compactness
• To effect proper streamlining and balancing of an
  aircraft, the shape and size of the engine must
  be compact.
• In a single engine aircraft, the shape and size
  of the engine will affect the view of the pilot.

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Engine Requirements

• Powerplant Selection

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Reciprocating Engine

• For aircraft whose cruising speeds will not
  exceed 250 MPH the reciprocating engine is the
  usual choice.
• Chosen for its excellent efficiency.
• Turbocharged or supercharged for high
• altitude use.
• -- Turbo-use exhaust
• -- Super-use accessory drive

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Turboprop Engine

• For cruising speeds from 180 to 350 MPH the
  turboprop engine performs better.
• Develops more power per pound then reciprocating.
• Operate most economically
• at high altitudes.

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Turbojet/Turbofan Engines

• Intended to cruise from high subsonic speeds up
  to Mach 2.0.
• Operates most efficiently at high altitudes.
• Less instrumentation and
• controls required.

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Types Of Reciprocating Engines
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In-Line Engines

• Generally has even number of cylinders.
• Liquid or air cooled.
• Has only one crankshaft.

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In-Line Engines

• Small Frontal area, better adapted to
  streamlining.
• When mounted inverted, it offers the added
  advantages of a shorter landing gear.
• High weight to horsepower ratio.

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V-type Engines

• Cylinders are arranged in two in-line banks
  generally set 30-60 apart.
• Even number of cylinders and are liquid or air
  cooled.

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Radial Engines

• Consists of a row, or rows, of cylinders arranged
  radially about a center crankcase.
• The number of cylinders composing a row may be
  either three, five, seven, or nine.

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Radial Engines

• Proven to be very rugged and dependable.
• High horsepower.

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Rotary-Radial

• Used during World War I by all of the warring
  nations.
• Cylinders mounted radially around a small
  crankcase and rotate with the propeller.

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Rotary-Radial

• Torque and gyro effect made aircraft difficult to
  control.
• Problems with carburetion, lubrication, and
  exhaust.

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Opposed Or O-type Engines

• Two banks of cylinders opposite each other with
  crankshaft in the center.
• Liquid or air cooled, air cooled version used
  predominantly in aviation.

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Opposed Or O-type Engines

• Has low weight-to-horsepower ratio.
• Its narrow silhouette makes it ideal for
  installation on wings.
• Little vibration.

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