Boeing 707, the first successful commercial passenger jetliner. The mid- to long-range narrow-body four-engine aircraft with a swept-wing design was developed and manufactured by the Boeing Company. It made its first flight on December 20, 1957, and entered commercial service on October 26, 1958.
Without an APU an aircraft would depend on GSE only for starting one engine with pressurized ground supplied air. Aircraft are allowed in general to fly without an APU. Another exception where an APU is needed could be an aircraft with safety architecture depending on an available APU.
The APU is a turbine engine that sits in the tail of the aircraft. It provides no thrust. Like any jet engine, it takes in air, compresses it, adds a fuel mixture and ignites it.
The engineering division dedicated the number 700 to jet-engined aircraft. Boeing's marketing division realized that the name 700 for their first jet aircraft would sound boring, so they suggested the name to be the 707, which had quite a nice ring to it.
| Boeing 707 |
|---|
| Number built | 1,010 |
| Unit cost | US$4.3 million (1955 dollars) US$36.5 million (2012 dollars) |
| Developed from | Boeing 367-80 |
| Variants | Boeing 720 Boeing C-137 Stratoliner |
The Boeing 720 is a four-engined low-wing cantilever monoplane. Although it was similar to the Boeing 707, compared with the 707-120, it was 9 ft (2.74 m) shorter in length, and had a lighter structure through use of lighter forged metal parts and thinner fuselage skins and structures.
Technical Specifications
| First flight | Dec. 20, 1957 |
|---|
| Length | 144 feet 6 inches |
| Gross weight | 248,000 pounds |
| Cruising speed | 600 mph |
| Range | 3,000 miles |
Since it was tradition to start the right engine first, they choose the left wing tank for this. So the APU starts to use some fuel from the left and then when the right engine is started first, it will help to partially balance the fuel.
The APU comes on to charge batteries discharged by the inverter feeding other AC loads. Many APUs have the same generator capacity as a propulsion engine. But they don't produce thrust. They can run at an optimum RPM for the generator requirements.
The APU can be started utilizing only the aircraft battery(s) and, once running, will provide electrical power to aircraft systems as well as bleed air for air conditioning and for engine start.
The APU often provides only electic and pneumatic power, but no hydraulic power. Hydraulic power can in this case e.g. be provided from an electric motor driven pump. The three power forms are called secondary power.
First, the APU runs on fuel and generally represents about 2-2.5% according to IATA. Air Conditioning Unit (ACU) and Ground Power Unit (GPU) can also be used to provide energy on the ground but should not be deployed in addition to the APU.
Because the 787 uses more electricity than do other Boeing airplanes, the 787 generates more electricity, via six generators: two on each engine and two on the auxiliary power unit (APU, a small turbine engine in the tail).
Aircraft APUs generally produce 115 V AC voltage at 400 Hz (rather than 50/60 Hz in mains supply), to run the electrical systems of the aircraft; others can produce 28 V DC voltage . APUs can provide power through single or three-phase systems.
Aircraft are designed in a way that allows them to glide through the air even with no engine thrust. Aircraft are able to fly through the movement of air passing over the wings and as long as this process continues the aircraft will continue to fly.
In recent years, airplane crashes have killed about a thousand people annually, whereas plane emissions kill about ten thousand people each year, researchers say. Airplane exhaust, like car exhaust, contains a variety of air pollutants, including sulfur dioxide and nitrogen oxides.
The 707 is no longer operated by major airlines. American actor John Travolta owned an ex-Qantas 707-138B, with the registration N707JT. In May 2017, he donated the plane to the Historical Aircraft Restoration Society near Wollongong, Australia.
McDonnell Douglas DC-9
| DC-9 |
|---|
| Status | In limited service |
| Primary users | USA Jet Airlines Aeronaves TSM Northwest Airlines (historical) Delta Air Lines (historical) |
| Produced | 1965–1982 |
| Number built | 976 |
The day a Douglas DC-8 busted Mach 1. On August 21, 1961, pilot William Magruder, copilot Paul Patten, flight engineer Joseph Tomich, and flight test engineer Richard H. The aircraft exceeded Mach 1—the only intentional supersonic flight by an airliner other than the Concorde and the Tu-144.
Who built the DC-8?
McDonnell Douglas
Douglas Aircraft Company
Takeover by Consolidated FreightwaysThe California company bought Emery on April 3, 1989, for $478 million.
Douglas DC8 Specs.
| Douglas DC-8 |
|---|
| Variant | Series 10 | Series 70 |
|---|
| Dimensions | |
| Number of Passengers (1 class) | 177 | -71/-73=259 -72=189 |
| Aircraft Length | 45.9 M(150 Ft 8 In) | -61/-63/-71/-73=57.1 M(187 Ft 5 In) -62/-72=48.0 M (157 Ft 6 In) |
In flight, engines provide all the needed energy (bleed air, hydraulic and electrical power). So the APU can be shut down shortly after engines are running.
The Boeing 747 cruising at 530 miles per hour at a weight of 700 000 pounds is seen to require 59 934 horsepower; the corresponding values for the Super Constellation are 330 miles per hour, 112 000 pounds, and 6585 horsepower.
Bleed air, extracted from either the Auxiliary Power Unit (APU) or another operating engine is used to power an air turbine starter motor to start the engine.
Start the APU 15 minutes before expected engine start. Shut it down as soon as the engines are started. Leave it off. After landing, if you're going to save costs by shutting down an engine (or 2 engines on a quad) during taxi in: start the APU first before shutting down the engine.
The differences between the twoThe main difference is the mobility – an APU is installed in an aircraft while a GPU is mobile can be used on different aircrafts. Despite that, there are certain aircrafts that are powered by both.
Yes it
can. A twin-
engine aircraft can fly perfectly well on only
one engine.
These steps are typically as follows:
- Disengage the Autothrottle – this stops automatic thrust control.
- Reduce the thrust on the damaged engine to idle – this involves moving the respective thrust lever all the way back to its idle position.
No it does not, it does not need one, there is a mechanical connection to the flight controls that can be used if all else fails. The B737 flight controls are hydraulically powered. There are three hydraulic systems: System A, System B, and Standby.
Each auxiliary power unit consists of a fuel tank, a fuel feed system, a system controller, an exhaust duct, lube oil cooling system, and fuel/lube oil vents and drains.
A Ground Power Unit (GPU) can be either a fixed or mobile unit which can be connected to the electrical system of an aircraft while on the ground to provide either 120V AC or 28V DC power.
