Wednesday, July 14, 2010
The Boeing 747, which is also known as the jumbo jet, is the largest passenger airliner in service. However, it will be surpassed by the Airbus A380 which is scheduled to enter service in late 2006. The four engine 747, produced by Boeing Commercial Airplanes, uses a two deck configuration where the small upper deck is usually used for business class. A typical three class layout accommodates about 400 passengers while a one class layout accommodates a maximum of 600 passengers. The hump created by the upper deck has made the 747 a highly recognizable icon of air travel.
The 747 flies at high subsonic speeds, typically 0.85 Mach or 565 mph or 909 km/h, and features intercontinental range (8,430 statute miles, or 13,570 km, for the 747-400 version) in some configurations sufficient to fly from New York to Hong Kong, roughly a third of the globe, non-stop. In 1989, a Qantas 747-400 flew non-stop from London to Sydney, a distance of 11,185 miles (18,000 km), in 20h 9 min, although this was a delivery flight with no passengers or freight. By May, 2005, a total of 1382 aircraft had been built or ordered in various 747 configurations, making it a profitable product for Boeing.
The 747 was born from the explosion of air travel in the 1960s. The era of commercial jet transportation, led by the enormous popularity of the Boeing 707, had revolutionized long distance travel and made possible the concept of the "global village." Boeing had already developed a study for a very large airplane while bidding on a US military contract for a huge airlifter. Boeing lost the contract to Lockheed's C-5 Galaxy but came under pressure from its most loyal airline customer, Pan Am, to develop a giant passenger plane which would be over twice the size of the 707. In 1966, Boeing proposed a preliminary configuration for the airliner to be called the 747. Pan Am ordered 25 of the initial 100 series. The design was a full length double decker but, due to issues with evacuation routes, this idea was scrapped in favor of a wide-body design.
At the time it was widely thought that the 747 would be replaced in the future with an SST (supersonic transport) design. Boeing made the shrewd move and designed the 747 so that it could easily be adapted to carry freight, knowing that when sales of the passenger version dried up it could remain in production as a cargo aircraft. The cockpit was moved to a shortened upper deck so that a nose loading door could be included, creating the 747's distinctive bulge. However, the supersonic transports such as Boeing's failed SST and the Concorde never lived up to their promise, being too expensive to operate profitably at a time when fuel prices were soaring. The upper deck was initially used as a luxurious first-class lounge/bar area, but is now most often used for extra seating capacity. After being expected to be obsolete with only 400 sales, the 747 outlived many of its critics and production passed the 1,000 mark in 1993. The expected slow-down in sales of the passenger version in favor of the cargo derivative has only happened in the early 2000s.
The development of the 747 was a huge undertaking. Boeing did not have a factory large enough to assemble the giant aircraft, so the company built an all new assembly building near Everett, Washington. This factory is the largest building ever built. Pratt and Whitney developed a massive high-bypass turbofan engine, the JT9D, that was, in the beginning, exclusively for the 747. To appease concerns about the safety and flyability of such a massive aircraft the 747 was designed with four backup hydraulic systems, split control surfaces, multiple structural redundancy, and sophisticated flaps which allow it to use standard length runways.
Initially, many airlines regarded the 747 with skepticism. Boeing's rivals, McDonnell Douglas and Lockheed, were working on wide-body, three engine tri-jets which were significantly smaller than the proposed 747. Many airlines believed the 747 would prove too large for an average long distance flight and, instead, invested in tri-jets. Furthermore, there was worry about whether the 747 would be compatible with existing airport infrastructure. Another issue raised by the airlines was fuel efficiency. A three engine airliner burns significantly less fuel per flight than a four engine and, with airlines trying to lower costs, fuel efficiency was an important issue that would return to haunt Boeing in the 1970s.
Boeing had promised to deliver the 747 to Pan Am by 1970, meaning that it had less than four years to develop, build, and test the airplane. Work progressed at such a breakneck pace that all those who worked on the development of the 747 were given the nickname "The Incredibles". The massive cost of developing the 747 and building the Everett factory meant that Boeing had gambled its very existence on the 747's success, and the company was nearly bankrupted in the early 1970s. The gamble paid off, however, and Boeing enjoyed a monopoly on very large passenger transports that has only been threatened 35 years later with the advent of the Airbus A380.
The 747 exists as several variants to address the specific needs of its numerous customers.
The first model of the jet, the 747-100, rolled out of the new Everett facility in September, 1968. The 747-100 entered service on January 1, 1970, with launch customer Pan American World Airways. It was later replaced by the 747-100B, a very similar aircraft with a stronger airframe and undercarriage design. Another 100 variant, the 747-100SR, has a capacity of up to 550 passengers and is used on domestic flights in Japan. The basic 100 has a range of about 4,500 miles (7,200 km) with full load.
Aircraft can be distinguished from one another by the upper deck which normally has only three windows. There are exceptions however. Some airlines purchased "SUD", or "stretched upper deck" modifications which make the upper deck almost identical to a 747-300.
Introduced in 1971, and further improved over successive years, the 747-200 has higher thrust and weight lifting capability than the 747-100, allowing it to fly further. It can usually be distinguished by its eight window upper deck, but, again, some airlines have given their 200 aircraft SUD, and a few early 200s had just 3 windows. The last models of the 200, built in the late 1980s, have a full load range of about 6,700 miles (10,800 km).
The 747-200C and 200F variants were designed to carry air freight. The 747-200F is a pure freighter while the 747-200C is a convertible aircraft that can carry either passengers or freight. A sub-variant is unofficially called the 747-200M and is a "combi" aircraft that can carry both at the same time. Like the 100, many 200s have been given a new lease on life as freight aircraft.
The 747SP, or "Special Performance," was first delivered in 1976. The SP was largely a stop-gap model to compete with the Douglas DC-10 and Lockheed L-1011 TriStar. The 747 was simply too big for many routes and Boeing did not have a mid-sized widebody to compete in the segment of the market that the DC-10 and TriStar had created. Crippled by the huge costs it had incurred in developing both the 737 and 747 in the late 1960s, Boeing could not afford to develop an all new design, so, instead, it shortened the 747 and reoptimized it for speed and range at the expense of capacity. The SP could only accommodate 220 passengers in a 3 class cabin but could fly over 6,500 miles (10,500 km) at speeds of up to 610 mph (980 km/h). Some airline insiders call it the "74 Short" or "Baby Jumbo" because of its shortened fuselage and stubby appearance. Originally designated 747SB, standing for Short Body, the airlines had Boeing change the production designation to 747SP.
The 747SP was the longest flying airliner available until the Airbus A340, and found its way into the fleets of American Airlines, Pan Am, and Qantas, airlines that needed its range for trans-South Pacific routes. American later used its 747SPs for service to Tokyo. The 747SP was also used by South African Airways on flights from Johannesburg to London during the Apartheid years when that airline's aircraft were not allowed to fly over African countries and had to fly around the Bulge of Africa. The extra range allowed aircraft to cover the additional distance.
For all its technical achievements, the SP never sold as well as Boeing hoped. Only 45 were ever built and most that are still in service are used by operators in the Middle East. The SOFIA astronomical observatory is a 747SP modified to carry a 2.5-meter-diameter infrared reflecting telescope. Originally it was delivered to Pan Am and titled "Clipper Lindbergh". NASA has displayed the name in Pan Am script on models of the plane. It will fly again in late 2005.
The first incarnation of the 747-300 would have been a tri-jet version of the 747SP, intended to compete with the DC-10 and L-1011 TriStar. This plan was scrapped due to insufficient demand. The 747-300 name was revived for a new aircraft introduced in 1980, and was the first 747 model to feature a stretched upper deck which increased its capacity over earlier models. Combi (747-300M) and Japanese domestic (747-300SR) models were also built. The upper deck was now accessed via a straight staircase rather than the spiral steps featured in the 100 and 200.
The 747-400 is the latest model of the 747, and also the only series still in production. It added 6ft(2m) wing tip entensions and 6ft(2m) winglets, an all new glass cockpit which dispensed with the need for a flight engineer, tail fuel tanks, revised engines, an all new interior, and newer in-flight entertainment to the basic design of the -300 series. It first entered service in 1989 with Northwest Airlines.
The -400 is available in the all passenger, combi (747-400M), and freighter (747-400F) variants. The Japanese domestic variant, the 747-400D, is the highest capacity passenger aircraft in the world and will be until the Airbus A380 officialy enters service. The -400D lacks the wing tip entensions and winglets included on other variants, allowing for increased number of takeoffs and landings by lowering wing stresses. The -400D may be converted to the long range version when needed.
The 747-400ER is an extended range version: it also comes in an all freight version, the 747-400ERF. Plans to develop a newer model, the 747-400XQLR, which stood for Quiet Long-Range (the X being a designator for an aircraft derivative which is still a design study and has not been officially launched), have evolved into the 747 Advanced.
747 Large Cargo Freighter
Boeing announced in October, 2003, that air transport will be the primary method of transportation for 7E7/787 parts, as opposed to shipping. Boeing will convert three passenger 747-400 aircraft into an oversize configuration in order to ferry subassemblies to Everett, Washington, for final assembly. It has a bulging fuselage like the Super Guppy or Airbus Beluga cargo planes used for transporting wings and fuselage sections. Delivery times will be reduced from around 30 days to one day with the 747 transporter. This is extremely important for the 787 as the wings are being produced by Japanese subcontractors.
The 747X was a proposed aircraft design that was similar to the proposed 747-500 among other 747 stretches. The proposal was dropped when Boeing decided to develop and commercialize the 747Adv (747 Advanced).
Boeing is now working with airlines to create a new 747 design called the Boeing 747 Advanced which will use the same engine and cockpit technology as the 787. The new 747 will be quieter, more economical, and more environmentally friendly. It will be capable of carrying up to 500 passengers in a 3 class configuration and fly over 8,000 nautical miles (14,816 km) at .86 Mach. It is rumored that British Airways, Japan Airlines, and Cathay Pacific have shown interest in this model. None of them have purchased the Airbus A380 as of yet.
Government and military
The current U.S. Presidential aircraft, VC-25A, is among the most famous 747 models. It is popularly known as Air Force One, even though that name refers to any United States Air Force aircraft carrying the President. VC-25A is based on the civilian Boeing 747-200. Other special 747s include the E-4B airborne emergency command and control post, modified 747s to transport the Space Shuttle, Shuttle Carrier Aircraft, and aerial refueling tankers. A recent addition to the military's 747 arsenal is the experimental Airborne Laser, a component of the National Missile Defense plan. A number of other governments also use the 747 as a VIP transport including Bahrain, Iran, Japan, Oman, Qatar, Saudi Arabia, Taiwan, and the United Arab Emirates.