Aviation Maintenance Technician

Powerplant

Dale Crane, Jerry Lee Foulk, David Scoggins

• Editorial: Aviation Supplies & Academics, Inc.
• Año: 2018
• ISBN:
  9781619546462
• Categoría: Technology & Engineering
• Categoría: Aviation

ASA's "Dale Crane Series" textbooks provide the most complete, up-to-date foundation for Aircraft & Powerplant (A&P) students and educators. The curriculum meets 14 CFR Part 147 course requirements and includes all of the aeronautical knowledge required for the FAA Knowledge Exams for AMTs (aircraft maintenance technicians). They are written and designed for at-home, classroom, or university level training. Powerplant is the final section of the FAA's required curriculum for AMTs, and covers all Part 147 course aspects of aircraft powerplant construction theory, maintenance and inspection -- that is, the engines and their related and connected systems. Detailing the technical maintenance of turbine and reciprocating engines, this book covers the final section of the FAA's required curriculum. Theory and construction of these engines are discussed, along with propellers, development of aircraft powerplants, and powerplant auxiliary systems. Each comprehensive textbook in the AMT Series includes full-color charts, tables, illustrations and photographs throughout, in addition to an extensive glossary, index, and additional career information. This series was created to set the pace for aircraft maintenance technician training and attain a level of quality that surpasses all other maintenance textbooks on the market. A study guide is included within each textbook in the form of Study Question sections, with Answer keys printed at the end of each chapter. These can be used for evaluation by an instructor or for self-testing. Therefore the AMTS textbooks are all-inclusive; no separate, inconvenient workbook is needed by the student or instructor. The Series is now edited by a team of subject matter experts.

1

Development of Aircraft Powerplants

powerplant. The complete installation of an aircraft engine, propeller, and all accessories needed for its proper function.

The first man-carrying flights were made in hot air balloons swept along by air currents and without means for the pilot to control the direction of flight. Aircraft had little practical utility until the development of engine-driven propellers. This development of the powerplant has made aviation the vital factor that it is today in the economic world.

The Principle of Heat Engines

heat engine. A mechanical device that converts chemical energy in a fuel into heat energy, and then into mechanical energy.

internal-combustion engine. A form of heat engine in which the fuel and air mixture is burned inside the engine.

All powered aircraft are driven by some form of heat engine. Chemical energy stored in the fuel is released as heat energy that causes air to expand. The expansion of this air is what performs useful work, driving either a piston or a turbine.

There are two basic types of heat engines: external-combustion and internal-combustion.

External-Combustion Engines

external-combustion engine. A form of heat engine in which the fuel releases its energy outside of the engine.

piston. The movable plug inside the cylinder of a reciprocating engine.

turbine. A wheel fitted with vanes or airfoils radiating out from a central disk. Used to extract energy from a stream of moving fluid.

Aerodrome. The name given by Dr. Samuel Langley to the flying machines built under his supervision between the years of 1891 and 1903.

External-combustion engines are most familiar to us as steam engines. Energy released in coal- or gas-fired furnaces or in nuclear reactors is transferred into water, changing it into steam that expands and drives either a piston or a turbine.

Steam engines were used to power experiments in flight made during the late 1800s. Dr. Samuel Langley of the Smithsonian Institution in Washington, D.C. used small steam engines to power a successful series of unmanned machines he called Aerodromes. In 1896, Dr. Langley made a number of powered flights with these models. The most successful had tandem wings with a span of 14 feet, weighed 26 pounds, and was powered by a one-horsepower steam engine. It was launched from a catapult atop a houseboat on the Potomac river, and flew for 90 seconds, traveling more than half a mile.

There was one successful but impractical aircraft steam engine developed in America in 1933 by the Besler brothers, manufacturers of logging locomotives. This 150-horsepower engine, using an oil-fired boiler and having a total installed weight of approximately 500 pounds, was used to power a Travel Air 2000 biplane.

Internal-Combustion Engines

Otto cycle of energy transformation. The four-stroke, five-event, constant-volume cycle of energy transformation used in a reciprocating engine.

gas turbine engine. An internal combustion engine that burns its fuel in a constant-pressure cycle and uses the expansion of the air to drive a turbine which, in turn, rotates a compressor. Energy beyond that needed to rotate the compressor is used to produce torque or thrust.

turbojet engine. A gas turbine engine that produces thrust by accelerating the mass of air flowing through it.

turbofan engine. A type of gas turbine engine in which lengthened compressor or turbine blades accelerate air around the outside of the core engine.

turboprop engine. A turbine engine in which energy extracted from the accelerated gases is used to drive a propeller.

turboshaft engine. A turbine engine in which energy extracted from the accelerated gases is used to drive helicopter rotors, generators, or pumps.

reciprocating engine. A type of heat engine that changes the reciprocating (back-and-forth) motion of pistons inside the cylinders into rotary motion of a crankshaft.

brake horsepower. The actual horsepower delivered to the propeller shaft of an aircraft engine.

cylinder. The component of a reciprocating engine which houses the piston, valves, and spark plugs and forms the combustion chamber.

The concept of releasing energy from fuel directly inside an engine to heat and expand the air has challenged engineers since the late 1700s. The expanding air can drive reciprocating pistons or spin turbines.

Coal dust, gunpowder, and even turpentine vapors have been exploded inside cylinders, but it was not until 1860 that the French engineer Etienne Lenoir actually built a practical engine that could use illuminating gas as its fuel.

In 1876, Dr. Nikolaus Otto of Germany made practical engines using the four-stroke cycle that bears his name, and it is the principal cycle upon which almost all aircraft reciprocating engines operate. This cycle of energy transformation is discussed in detail in Chapter 2.

Gas turbine engines in the form of turbojet, turbofan, turboprop, and turboshaft engines have revolutionized aviation, and their principle of operation is discussed in Chapter 10.

Aircraft Reciprocating Engines

Throughout the history of aviation, progress has always been dependent upon the development of suitable powerplants.

Aviation as we know it today was born at the beginning of the 1900s with powered flights made by Wilbur and Orville Wright. The Wright brothers approached the problems of flight in a sensible and professional way. They first solved the problem of lift with kites, then the problem of control with gliders, and finally by 1902, they were ready for powered flight. First they painstakingly designed the propellers and then began their search for a suitable engine. Their requirements were for a gasoline engine that would develop 8 or 9 brake horsepower and weigh no more than 180 pounds. No manufacturer had such an engine available, and none were willing to develop one for them. Their only recourse was to design and build it on their own.

The engine, built to their design by Mr. Charles Taylor, had four cylinders in-line and lay on its side. It drove two 81⁄2-foot-long wooden propellers through chain drives and developed between 12 and 16 horsepower when it turned at 1,090 RPM. It weighed 179 pounds.

On December 17, 1903, this engine powered the Wright Flyer on its historic flight of 59 seconds, covering a distance of 852 feet on the wind-swept sand at Kitty Hawk, North Carolina.

Because of Dr. Langley’s success with his Aerodromes, the U.S. government gave him a contract to build a full-scale man-carrying machine. The steam engines used in the models could not be effectively scaled up to power this aircraft, so a better means of propulsion had to be found.

Charles Manly, Dr. Langley’s assistant, searched without success, both in the United States and Europe, for a suitable powerplant. The best he found was a three-cylinder rotary radial automobile engine built by Stephen Balzer in New York. This engine was not directly adaptable to the Aerodrome, but Manly, building upon Balzer’s work, constructed a suitable engine for it. The Manly-Balzer engine was a five-cylinder, water-cooled static radial engine that produced 52.4 horsepower at 950 RPM and weighed 207.5 pounds complete with water.

On October 7, 1903, the full-scale Aerodrome with Manly as the pilot was launched from atop the houseboat. As the aircraft neared the end of the catapult, it snagged part of the launching mechanism and was dumped into the river. But Manly’s engine, which was far ahead of its time, functioned properly and was in no way responsible for the failure of the Aerodrome to achieve powered flight.

dirigible. A large, cigar-shaped, lighter-than-air flying machine. Dirigibles differ from balloons in that they are powered and can be steered.

rotary radial engine. A form of reciprocating engine in which the crankshaft is rigidly attached to the airframe and th...