Piston Engine Classification and Types

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Questions and Answers

What classification of engine is characterized by a row of cylinders arranged radially about a central crankcase?

  • RADIAL TYPE (correct)
  • IN-LINE TYPE
  • V-TYPE
  • DOUBLE V TYPE

Which cooling method involves the direct transfer of heat from cylinders to the surrounding air?

  • Liquid-cooled
  • Air-cooled (correct)
  • Hybrid-cooled
  • Steam-cooled

Which type of radial engine rotates with the propeller and was widely used during World War I?

  • Rotary-radial (correct)
  • Static-radial
  • Single row
  • Double row

What is a common disadvantage of rotary-radial engines as mentioned?

<p>Difficulty in control due to torque (B)</p> Signup and view all the answers

How many strokes per cycle classify engines into two-stroke or four-stroke types?

<p>Two or four strokes (A)</p> Signup and view all the answers

What type of piston engine is characterized by its arrangement with the crankshaft in a 'V' configuration?

<p>V-TYPE (A)</p> Signup and view all the answers

Which of the following types is NOT a classification based on cylinder arrangement?

<p>Barrel TYPE (A)</p> Signup and view all the answers

What is the primary method of heat transfer in liquid-cooled engines?

<p>To coolant to radiator (B)</p> Signup and view all the answers

What are the typical total numbers of cylinders in a double-row radial engine?

<p>14 or 18 (D)</p> Signup and view all the answers

Which engine type is characterized by a crankshaft that is horizontal in most light aircraft?

<p>Opposed-Type Engine (D)</p> Signup and view all the answers

What is a significant advantage of the opposed-type engine over other types?

<p>Low weight-to-horsepower ratio (A)</p> Signup and view all the answers

What is a common disadvantage associated with radial engines?

<p>High drag due to large frontal area (B)</p> Signup and view all the answers

Which of the following describes the configuration of cylinders in a V-type engine?

<p>Two banks arranged to form a 'V' (A)</p> Signup and view all the answers

What was a significant contribution of the static-radial engine to aviation in the late 1920s?

<p>Improved reliability for long-distance flights (C)</p> Signup and view all the answers

How are the pistons of a single-row radial engine connected to the crankshaft?

<p>Single-throw 360° crankshaft (A)</p> Signup and view all the answers

Which feature does the design of a V-12 engine primarily offer?

<p>Higher horsepower in reduced space (B)</p> Signup and view all the answers

What cooling method challenges the V-type engine design?

<p>Difficulties in cooling by air (C)</p> Signup and view all the answers

What role does the staggered arrangement of cylinders in a double-row radial engine serve?

<p>Ensures cylinders receive ram air for cooling (D)</p> Signup and view all the answers

In which scenario are in-line engines generally used?

<p>Confined to low- and medium-horsepower engines (C)</p> Signup and view all the answers

What does the design of an inverted in-line engine offer as an advantage?

<p>Shorter landing gear combined with better visibility (D)</p> Signup and view all the answers

Which factor contributes to the radial engine’s status as a preferred choice for large aircraft?

<p>Dependability and efficiency in high horsepower applications (D)</p> Signup and view all the answers

What is the primary advantage of the horizontally-opposed air-cooled engine?

<p>Low weight and ease of cooling (B)</p> Signup and view all the answers

Which code indicates that an engine has left-hand rotation for a counter-rotating propeller?

<p>L (D)</p> Signup and view all the answers

What defines the firing order in multi-cylinder engines?

<p>The number of cylinders and arrangement of cranks (D)</p> Signup and view all the answers

What is the ignition interval for a six-cylinder engine?

<p>120° (C)</p> Signup and view all the answers

What is the main disadvantage of V-type engines?

<p>Cooling difficulties (D)</p> Signup and view all the answers

Which engine designation indicates an aerobatic engine designed for inverted flight?

<p>A (B)</p> Signup and view all the answers

What is indicated by the three-digit numbers in an engine’s designation?

<p>Displacement to the nearest 10 in³ (A)</p> Signup and view all the answers

Which of the following engines is no longer manufactured for general aircraft use?

<p>Double-V engines (B)</p> Signup and view all the answers

What does the 'G' suffix in engine designations indicate?

<p>Geared nose section for propeller rpm reduction (A)</p> Signup and view all the answers

In terms of engine operation, what is the primary advantage of having multiple cylinders?

<p>Smoother operation and uniform torque development (C)</p> Signup and view all the answers

What is a primary characteristic of the opposed engine design?

<p>Compact and efficient cooling (D)</p> Signup and view all the answers

Which letter designation might indicate an engine equipped with a dual magneto?

<p>D (C)</p> Signup and view all the answers

For which type of installation would the 'V' designation be used in engine identification?

<p>Vertical engine positioning for helicopters (D)</p> Signup and view all the answers

What is a typical firing order for a four-cylinder engine?

<p>1-3-4-2 (D)</p> Signup and view all the answers

Flashcards

Radial engine

A type of engine with cylinders arranged radially around a central crankcase.

Rotary-radial engine

A radial engine where the cylinders rotate along with the propeller.

Static-radial engine

A radial engine where the cylinders are fixed and only the crankshaft rotates.

In-line engine

A type of reciprocating engine where the cylinders are arranged in a line along a common crankshaft.

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Upright in-line engine

An in-line engine where the cylinders are positioned above the crankshaft.

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Inverted in-line engine

An in-line engine where the cylinders are positioned below the crankshaft.

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V-type engine

A type of engine with two banks of cylinders arranged in a V-shape, sharing a common crankshaft.

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Double V-type engine

A type of engine with two V-type engine configurations placed opposite each other, sharing a common crankshaft.

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Horizontally Opposed Engine

The arrangement of cylinders in an engine where they are positioned horizontally opposed to each other, with a crankshaft in the middle.

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Engine Designation Code

A system used by some manufacturers to identify engine types and characteristics using letter codes.

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Engine Designation: "L"

The code "L" in engine designation indicates left-hand rotation of the propeller.

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Engine Designation: "T"

The code "T" in engine designation indicates a turbocharged engine.

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Engine Designation: "V" (Helicopter)

The code "V" in engine designation indicates a vertical crankshaft position for helicopter installation.

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Engine Designation: "H" (Helicopter)

The code "H" in engine designation indicates a horizontal crankshaft position for helicopter installation.

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Engine Designation: "A"

The code "A" in engine designation indicates an engine designed for aerobatic maneuvers, including inverted flight.

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Engine Designation: "I"

The code "I" in engine designation indicates a fuel-injected engine.

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Engine Designation: "G"

The code "G" in engine designation indicates a geared nose section for propeller RPM reduction.

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Engine Designation: "S"

The code "S" in engine designation indicates a supercharged engine, capable of operating at higher manifold pressure.

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Engine Designation: "O"

The code "O" in engine designation indicates an opposed cylinder configuration.

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Engine Designation: "R"

The code "R" in engine designation indicates a radial cylinder arrangement.

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Opposed-type engine

A type of reciprocating engine with two banks of cylinders directly opposite each other, with a crankshaft in the center.

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Double-row radial engine

A type of radial engine where the cylinders are arranged in two rows, each with an odd number of cylinders. Typical configurations use either 14 or 18 cylinders.

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Radial engine: Weight-to-horsepower ratio

Radial engines are known for their low weight-to-horsepower ratio, making them ideal for aircraft.

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Radial engine: Drag

The main disadvantage of radial engines is their large frontal area, which contributes to increased drag.

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Radial engine: Reliability and efficiency

Radial engines are known for their reliability and efficiency, making them a popular choice for large aircraft.

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In-line engine: Streamlining

In-line engines are better suited to streamlining due to their smaller frontal area.

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In-line engine: Weight-to-horsepower ratio

In-line engines generally have a higher weight-to-horsepower ratio compared to radial engines.

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V-type engine: Weight-to-horsepower and streamlining

V-type engines offer a good balance between weight-to-horsepower ratio and streamlining.

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Opposed-type engine: Efficiency and dependability

Opposed-type engines are known for their efficiency, dependability, and low weight-to-horsepower ratio, making them popular for light aircraft.

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Opposed-type engine: Streamlining

Opposed-type engines are well-suited for streamlining due to their flat shape.

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Study Notes

Piston Engine Classification

  • Reciprocating engines are classified by cylinder arrangement, cooling method (liquid or air-cooled), and number of strokes per cycle (two-stroke or four-stroke).
  • Air-cooled engines transfer excess heat directly to the surrounding air.
  • Liquid-cooled engines transfer heat from cylinders to coolant, which is then cooled in a radiator.
  • Cylinder arrangement is the most descriptive classification method.

Piston Engine Types

  • Radial: Cylinders arranged radially around a central crankcase. Includes rotary-radial, static-radial, single-row, double-row, and multiple-row.

    • Rotary-radial: Cylinders rotate with the propeller. Provides high horsepower-to-weight ratio but is less reliable due to carburetion, lubrication, and exhaust problems.
    • Static-radial: Cylinders are stationary relative to the crankcase, more reliable. Allowed long-distance flights.
    • Single-row: Odd number of cylinders extending radially from the crankshaft centerline.
    • Double-row: Two single-row engines on a single crankshaft, with staggered cylinders. High reliability and efficiency.
  • In-line: Cylinders arranged in a straight line with the crankshaft above or below. Commonly has an even number of cylinders (though some 3-cylinder engines exist). Shorter frontal area and better for streamlining. Inverted design offers shorter landing gear and improved pilot visibility, however air-cooling is more challenging with increasing engine size.

  • V-type: Cylinders arranged in two in-line banks forming a V-shape, often with 60, 90, or 45 degree separation, mostly 8 or 12 cylinders. Two sets of connecting rods on the same crankpin, reducing weight. Air-cooling is more difficult.

  • Opposed (or Flat) type: Two banks of cylinders directly opposed with a single crankshaft. Either vertical/horizontal mount. More compact, efficient, reliable, and economical configuration for light aircraft. High suitability for streamlining and horizontal installation.

  • Double V (or Fan): This type is less common.

  • X-type: Another less common design

Engine Designation

  • Manufacturers use a code system followed by a numerical indication of displacement (e.g., 470'). Letters in the code indicate engine characteristics (e.g., L for left-hand rotation, T for turbocharged, V for vertical, R for radial, O for opposed cylinders).

Firing Order and Ignition

  • Multi-cylinder engines have a firing order, the sequence in which cylinders ignite.
  • Ignition intervals vary depending on the number of cylinders (e.g., 360° for twin, 180° for four, 120° for six, and 90° for eight).
  • Firing order is determined by crank throw positions on the crankshaft and cam lobe positions on the camshaft.
  • Firing order isn't sequential but is optimized for smooth operation.
  • Normal opposed engines tend to alternate cylinders from front to back, like 1-3-4-2 for a 4 cylinder engine or 1-6-3-2-5-4 for a 6 cylinder engine.

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