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An auxiliary power unit (APU) is a device on a vehicle whose purpose is to provide energy for functions other than propulsion. Different types of APU are found on aircraft, as well as some large ground vehicles. Image File history File links Metadata Size of this preview: 800 × 600 pixelsFull resolution (2560 × 1920 pixel, file size: 1. ...
Image File history File links Metadata Size of this preview: 800 × 600 pixelsFull resolution (2560 × 1920 pixel, file size: 1. ...
The Airbus A380 is a double-deck, four-engined airliner manufactured by EADS (Airbus S.A.S.). It is the largest passenger airliner in the world. ...
Aircraft An aircraft APU is a relatively small, self-contained generator used to start the jet engines, usually with compressed air, and to provide electricity, hydraulic pressure and air conditioning while the aircraft is on the ground. In many aircraft, the APU can also provide electrical power in the air. ImageMetadata File history File links APIC-Honeywell-APU-Airbus. ...
ImageMetadata File history File links APIC-Honeywell-APU-Airbus. ...
The APU exhaust at the tail end of an Airbus A380 An auxiliary power unit (APU) is a device on a vehicle whose purpose is to provide energy for functions other than propulsion. ...
Airbus S.A.S. is the aircraft manufacturing subsidiary of EADS N.V., a pan-European aerospace concern. ...
“Dynamo†redirects here. ...
A Pratt and Whitney turbofan engine for the F-15 Eagle is tested at Robins Air Force Base, Georgia, USA. The tunnel behind the engine muffles noise and allows exhaust to escape. ...
Lightning strikes during a night-time thunderstorm. ...
A gasoline piston engine APU was first used on the Pemberton-Billing P.B.31 Nighthawk Scout aircraft in 1916. The Boeing 727 in 1963 was the first jetliner to feature a gas turbine APU, allowing it to operate at smaller, regional airports, independent from ground facilities. Noel Pemberton Billing (1881-1948) was a British aviator and Member of Parliament known for his extreme right-wing views. ...
Supermarine P.B.31E Nighthawk The P.B.31E Night Hawk, the first project of the Pemberton-Billing operation after it became Supermarine Aviation Works Ltd. ...
The Boeing 727 is a mid-size, narrow-body, three-engine commercial jet airliner. ...
This machine has a single-stage centrifugal compressor and turbine, a recuperator, and foil bearings. ...
Although APUs have been installed in many locations on various military and commercial aircraft, they are usually mounted at the rear of modern jet airliners. The APU exhaust can be seen on most modern airliners as a small pipe exiting at the aircraft tail. The de Havilland Comet 1 G-ALYP A jet airliner is any airliner powered by jet engines. ...
In most cases the APU is powered by a small gas turbine engine that provides compressed air from within or drives an air compressor (load compressor). Recent designs have started to explore the use of the Wankel engine in this role. The Wankel offers power-to-weight ratios better than normal piston engines and better fuel economy than a turbine. Compressor has several meanings: A gas compressor is a mechanical device that takes in a gas and increases its pressure by squeezing a volume of it into a smaller volume. ...
Wankel Engine in Deutsches Museum Munich, Germany The Wankel rotary engine is a type of internal combustion engine, invented by German engineer Felix Wankel, which uses a rotor instead of reciprocating pistons. ...
Power-to-weight ratio is a measure commonly used when comparing various vehicles (or engines), including automobiles, motorcycles and aircraft. ...
Components of a typical, four stroke cycle, DOHC piston engine. ...
APUs fitted to ETOPS (Extended-range Twin-engine Operations) are a critical safety device, as they supply backup electricity and compressed air in place of the dead engine or failed main engine generator. While some APUs may not be startable while the aircraft is in flight, ETOPS compliant APUs must be flight-startable at up to the aircraft service ceiling. Recent applications have specified starting up to 43,000 ft (≈ 13,000 m) from a complete cold-soak condition. If the APU or its electrical generator is not available, the airplane cannot be released for ETOPS flight and is forced to take a longer route. ETOPS (Extended-range Twin-engine Operational Performance Standards) is an acronym for an International Civil Aviation Organization (ICAO) rule permitting twin-engined commercial air transports to fly routes that, at some points, are further than a distance of 60 minutes flying time from an emergency or diversion airport. ...
APUs are even more critical for space shuttle flight operations. Unlike aircraft APU's, they provide hydraulic pressure, not electrical power. The space shuttle has three redundant APUs, powered by hydrazine fuel. They only function during powered ascent and during re-entry and landing. During powered ascent, the APUs provide hydraulic power for gimballing of shuttle's engines and control surfaces. During landing, they power the control surfaces and brakes. Landing can be accomplished with only one APU working. On STS-9, two of Columbia's APUs caught fire, but the flight still landed successfully. For the current Space Shuttle mission, see STS-117 NASAs Space Shuttle, officially called Space Transportation System (STS), is the United States governments current manned launch vehicle. ...
Hydraulics is a branch of science and engineering concerned with the use of liquids to perform mechanical tasks. ...
In engineering, the duplication of critical components of a system with the intention of increasing reliability of the system, usually in the case of a backup or fail-safe, is called redundancy. ...
Hydrazine should not be confused with Hydergine (Ergoloid mesylates) an ergot alkaloid Hydrazine is the chemical compound with formula N2H4, widely used in chemical synthesis. ...
Atmospheric entry is the transition from the vacuum of space to the atmosphere of any planet or other celestial body. ...
A gimbal is a mechanical device that allows the rotation of an object in multiple dimensions. ...
A cold (un-ignited) rocket engine test at NASA A rocket engine is a reaction engine that can be used for spacecraft propulsion as well as terrestrial uses, such as missiles. ...
A flight control system consists of the flight control surfaces, the respective cockpit controls, connecting linkage, and necessary operating mechanisms to control aircraft in flight. ...
This article needs additional references or sources for verification. ...
STS-9 (Spacelab 1) was a United States Space Shuttle mission, the 6th mission of the Columbia orbiter. ...
Space Shuttle Columbia (NASA Orbiter Vehicle Designation: OV-102) was the first spaceworthy space shuttle in NASAs orbital fleet. ...
A typical gas turbine APU for commercial transport aircraft comprises three main sections:
- Power section
- Load compressor
- Gearbox
The power section is the gas generator portion of the engine and produces all the shaft power for the APU. The load compressor is generally a shaft‐mounted compressor that provides pneumatic power for the aircraft, though some APUs extract bleed air from the power section compressor. There are two actuated devices, the inlet guide vanes that regulate airflow to the load compressor and the surge control valve that maintains stable or surge‐free operation of the turbo machine. The third section of the engine is the gearbox. The gearbox transfers power from the main shaft of the engine to an oil‐cooled generator for electrical power. Within the gearbox, power is also transferred to engine accessories such as the fuel control unit, the lube module, and cooling fan. In addition, there is also a starter motor connected through the gear train to perform the starting function of the APU. Some APU designs use combination starter/generator for APU starting and electrical power generation to reduce compelexity. A gearbox is an assembly of gears allowing the rotational speed of an input shaft to be changed to a different speed. ...
With the Boeing 787 being an all electric airplane, the APU delivers only electricity to the aircraft. The absence of pneumatic system simplifies the design, but the demand for hundreds of kilowatts (kW) of electricity requires heavier generators and unique system requirements. The Boeing 787 Dreamliner is an American mid-sized, wide-body, twin engine jet airliner currently in production by Boeings Commercial Airplanes division and scheduled to enter service in May 2008. ...
The watt (symbol: W) is the SI derived unit of power, equal to one joule per second. ...
Two main corporations compete in the aircraft APU market: United Technologies Corporation, through its subsidiaries Hamilton Sundstrand and Pratt & Whitney Canada, and Honeywell International Inc. United Technologies Corporation (UTC) (NYSE: UTX) is a multinational corporation based in Hartford, Connecticut, USA, and is the 20th largest U.S. manufacturer. ...
Hamilton Sundstrand, owned by UTC, is headquartered in Windsor Locks, Connecticut. ...
Pratt & Whitney Canada (PWC) is a Canadian aircraft engine manufacturer. ...
Honeywell Heating Specialties Company Stock Certificate dated 1924 signed by Mark C. Honeywell - courtesy of Scripophily. ...
In case of APU failure an air start unit (ASU) and ground power unit (GPU), respectively is needed.
Armor APUs are also fitted to some tanks to provide electrical power when stationary, without the high fuel consumption caused by running the main engine.
Commercial Vehicles Some commercial vehicles now mount auxiliary power units of their own. A typical APU for a commercial truck is a small diesel engine with its own cooling system, generator, and air conditioning compressor, mounted to one of the frame rails of a semi-truck. This unit is used to provide climate control and electrical power for the truck's sleeper cab and engine block heater during downtime on the road. This article does not cite any references or sources. ...
semi-trailer truck with sleeper behind the cab. ...
In the United States, federal Department of Transportation regulations require 10 hours of rest for every 11 hours of driving. During these times, truck drivers often idle their engines to provide heat, light, and power for various comfort items. Although diesel engines are very efficient when idling, it is still financially and environmentally costly to idle them like this, from a fuel consumption and an engine wear perspective. The APU is designed to eliminate these long idles. Since the generator engine is a fraction of the main engine's displacement, it uses a fraction of the fuel; some models can run for eight hours on a gallon (≈ 4 litres) of diesel. The generator also powers the main engine's block and fuel system heaters, so the main engine can be started easily right before departure if the APU is allowed to run for a period beforehand. An APU can save five gallons (≈ 19 litres) of fuel a day, and can extend the useful life of the main engine by around 100,000 miles (≈ 160,000 kilometres), by reducing non-productive run time. The Department of Transportation (DOT) is the most common name for a government agency in North America devoted to transportation. ...
Some vehicle APUs can also use an external shore power connection for their heating and cooling functions, thus eliminating fuel consumption during rest periods altogether. Many truck stops already provide shore power connections in their parking areas.
As an alternative to the diesel units, APUs using an auxiliary battery system or hydrogen fuel cells as a source of power have also been designed. Freightliner has shown a demonstration model of a fuel cell APU, run on a tank of liquid hydrogen mounted to the truck, on one of their Century Class S/T road tractors. There are two entries concerning Freightliner For the Freightliner Truck Company, please see Freightliner (truck) For the United Kingdom Rail Company, please see Freightliner_(UK) This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...
General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ...
On some older diesel engines an APU was used instead of an electic motor to start the main engine. These were primarily used on large pieces of construction equipment.
External links - "Armor-plated auxiliary power" design of a modern gas turbine APU
- "Space Shuttle Orbiter APU"
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