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105-649: The S-duct was invented as a solution for positioning the central engine on trijets. The S-duct is easier to service than alternative trijet designs. Most trijet designs opted for the S-duct layout. Only the McDonnell Douglas DC-10 and MD-11 trijets' designers chose not to use the S-duct and go with a "straight-through" layout. The straight-through layout leaves the engine high above the ground, making access difficult. The straight-through layout also increases total aerodynamic drag by 2–4%. Compared to

210-401: A Boeing 777 -300 reaches that point at 3,000 nautical miles (5,600 km). It is more fuel-efficient to make a non-stop flight at less than this distance and to make a stop when covering a greater total distance. Very long non-stop passenger flights suffer from the weight penalty of the extra fuel required, which means limiting the number of available seats to compensate. For such flights,

315-424: A deadheading DC-10 flight instructor, performed a partially controlled emergency landing by constantly adjusting the thrust of the remaining two engines; 185 people on board survived, but 111 others died, and the aircraft was destroyed. The DC-10 was designed without backup flight controls because it was considered extremely improbable that all hydraulic systems would fail. However, due to their close proximity under

420-487: A jet engine with its efficiency given by its airspeed divided by the thrust-specific fuel consumption and the specific energy of the fuel. Turboprops have an optimum speed below 460 miles per hour (740 km/h). This is less than jets used by major airlines today, however propeller planes are much more efficient. The Bombardier Dash 8 Q400 turboprop is used for this reason as a regional airliner. Jet fuel cost and emissions reduction have renewed interest in

525-475: A 3,500- nautical-mile [nmi] (6,500 km; 4,000 mi) range for transcontinental flights . The DC-10-15 had more powerful engines for hot and high airports. The DC-10-30 and –40 models (with a third main landing gear leg to support higher weights) each had intercontinental ranges of up to 5,200 nmi (9,600 km; 6,000 mi). The KC-10 Extender (based on the DC-10-30) is a tanker aircraft that

630-475: A 57 g/RPK CO₂ emissions (equivalent to 18.1 g/km of fuel, 2.27 L/100 km [104 mpg ‑US ] per passenger), 40% lower than IAG or Lufthansa (95 g CO₂/RPK - 30 g/km of fuel, 3.8 L/100 km [62 mpg ‑US ] per passenger), due to their business classes , lower-density seating , and flight connections . In 2021, the highest seating density in its A330neo , with 459 single-class seats, enabled Cebu Pacific to claim

735-468: A compounded annual reduction 1.3% with a variable reduction rate. In 2018, CO₂ emissions totalled 747 million tonnes for passenger transport, for 8.5 trillion revenue passenger kilometres (RPK), giving an average of 88 grams CO₂ per RPK; this represents 28 g of fuel per kilometre, or a 3.5 L/100 km (67 mpg ‑US ) fuel consumption per passenger, on average. The worst-performing flights are short trips of from 500 to 1500 kilometres because

840-600: A damaged door seal. Yield management allows the optimization of the load factor , benefiting the fuel efficiency , as is the air traffic management optimization. By taking advantage of wake updraft like migrating birds ( biomimicry ), Airbus believes an aircraft can save 5-10% of fuel by flying in formation , 1.5–2 nmi (2.8–3.7 km) behind the preceding one. After Airbus A380 tests showing 12% savings, test flights were scheduled for 2020 with two Airbus A350s , before transatlantic flight trials with airlines in 2021. Certification for shorter separation

945-655: A fuel consumption of 58 mpg ‑US (4.06 L/100 km) per revenue passenger for domestic flights, or 32.5 g of fuel per km, generating 102 g CO₂ / RPK of emissions. In 2013, the World Bank evaluated the business class carbon footprint as 3.04 times higher than economy class in wide-body aircraft , and first class 9.28 times higher, due to premium seating taking more space, lower weight factors, and larger baggage allowances (assuming Load Factors of 80% for Economy Class, 60% for Business Class, and 40% for First Class). At constant propulsive efficiency,

1050-707: A fuel tanker in the air." Singapore Airlines Flights 21 and 22 were re-launched in 2018 with more seats in an A350-900 ULR. In the late 2000s/early 2010s, rising fuel prices coupled with the Great Recession caused the cancellation of many ultra-long haul, non-stop flights. This included the services provided by Singapore Airlines from Singapore to both Newark and Los Angeles that was ended in late 2013. But as fuel prices have since decreased and more fuel-efficient aircraft have come into service, many ultra-long-haul routes have been reinstated or newly scheduled (see Longest flights ). The efficiency can be defined as

1155-669: A high density of 1.36 seat/m due to a low 9% premium seating. On the other side, the least efficient was British Airways at 27 pax-km/L (3.7 L/100 km [64 mpg ‑US ] per passenger), using fuel-inefficient Boeing 747-400s with a low density of 0.75 seat/m due to a high 25% premium seating, in spite of a high 82% load factor. In 2018, CO₂ emissions totalled 918 Mt with passenger transport accounting for 81% or 744 Mt, for 8.2 trillion revenue passenger kilometres : an average fuel economy of 90.7 g/RPK CO₂ - 29 g/km of fuel (3.61 L/100 km [65.2 mpg ‑US ] per passenger) In 2019, Wizz Air stated

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1260-408: A maximum payload range of 4,604 miles (4,001 nmi; 7,409 km). The series 40 had a typical load range of 5,750 miles (5,000 nmi; 9,250 km) and a maximum payload range of 4,030 miles (3,500 nmi; 6,490 km). The DC-10 had two engine options and introduced longer-range variants a few years after entering service; these allowed it to distinguish itself from its main competitor,

1365-452: A range of 3,800 miles (3,300 nmi; 6,100 km) with a typical passenger load and a range of 2,710 miles (2,350 nmi; 4,360 km) with maximum payload. Various models of the DC-10 promptly followed, such as the series 15, which had a typical load range of 4,350 miles (3,780 nmi; 7,000 km). The series 20 was powered by Pratt & Whitney JT9D turbofan engines, whereas

1470-522: A rear center landing gear . It was to use Pratt & Whitney JT9D -15 turbofan engines, each producing 45,500 lbf (202 kN) of thrust, with a maximum takeoff weight of 530,000 pounds (240 t). However, engine improvements led to increased thrust and increased takeoff weight. Northwest Orient Airlines, one of the launch customers for this longer-range DC-10 requested the name change to DC-10-40. A proposed version with Rolls-Royce RB211 -524 engines for British Airways. The order never came and

1575-400: A reliable aircraft with a low overall accident rate as of 1998. The DC-10's initially poor safety record has continuously improved as design flaws were rectified and fleet hours increased. The DC-10's lifetime safety record is comparable to similar second-generation passenger jets as of 2008. The DC-10 has cargo doors that open outward; this allows the cargo area to be completely filled, as

1680-694: A route like Bangkok–Tokyo: direct routing saves 190 kg (420 lb) fuel by flying 40 km (25 mi) less; 600 kg (1,300 lb) more fuel is consumed if flying 600 m (2,000 ft) below optimum altitude without vertical flight profile optimization; cruising Mach 0.01 above the optimum speed consumes 800 kg (1,800 lb) more fuel; 1,000 kg (2,200 lb) more fuel on board consumes 150 kg (330 lb) more fuel while 100 litres (22 imp gal; 26 US gal) of unused potable water consumes 15 kg (33 lb) more fuel. Operational procedures can save 35 kg (77 lb) fuel for every 10-minute reduction in use of

1785-415: A seating configuration that exacerbated the effects of decompression, and as the cabin floor collapsed into the cargo bay, control cables were severed and the aircraft became uncontrollable. Investigators found that the DC-10's relief vents were not large enough to equalize the pressure between the passenger and cargo compartments during explosive decompression. Following this crash, a special subcommittee of

1890-463: A solely McDonnell Douglas product, but none proceeded beyond design studies. The KC-10 Extender is a military version of the DC-10-30CF for aerial refueling . The aircraft was ordered by the U.S. Air Force and delivered from 1981 to 1988. A total of 60 were built. These aircraft are powered exclusively by General Electric CF6 turbofan engines. The KDC-10 was an aerial refueling tanker for

1995-496: A specifically designed aircraft, such as the (discontinued) Aerion AS2 , the Mach ;1.1 range at 3,700 nmi is 70% of the maximum range of 5,300 nmi at Mach 0.95, but increases to 4,750 nmi at Mach 1.4 for 90% before falling again. Wingtip devices increase the effective wing aspect ratio , lowering lift-induced drag caused by wingtip vortices and improving the lift-to-drag ratio without increasing

2100-673: A subsonic turbofan aircraft. Airbus states a fuel rate consumption of their A380 at less than 3 L/100 km per passenger (78 passenger-miles per US gallon). Newer aircraft like the Boeing 787 Dreamliner , Airbus A350 and Bombardier CSeries , are 20% more fuel efficient per passenger kilometre than previous generation aircraft. For the 787, this is achieved through more fuel-efficient engines and lighter composite material airframes, and also through more aerodynamic shapes, winglets , more advanced computer systems for optimising routes and aircraft loading. A life-cycle assessment based on

2205-476: A surge in demand for widebody airliners. However, the Boeing 747-400 , MD-11, Airbus A330 / A340 , and soon-to-be-built Boeing 777 were all behind schedule and couldn't fully meet the demand for widebody airliners. Production of first-generation widebodies like the Boeing 747-100 / 200 / 300 , L-1011, and DC-10 had already stopped, so the value of used DC-10-30s almost doubled, rising from less than $ 20 million to almost $ 40 million. The McDonnell Douglas DC-10

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2310-423: A time when air crew labor costs were higher relative to fuel costs. Despite the high fuel consumption, because fuel was inexpensive in that era the higher speed resulted in favorable economical returns since crew costs and amortization of capital investment in the aircraft could be spread over more seat-miles flown per day. Productivity including speed went from around 150 ASK /MJ*km/h for the 1930s DC-3 to 550 for

2415-462: A variable-pitch propfan that produced less noise and achieved high speeds. In Europe in 2017, the average airline fuel consumption per passenger was 3.4 L/100 km (69 mpg ‑US ), 24% less than in 2005, but as the traffic grew by 60% to 1,643 billion passenger kilometres , CO₂ emissions were up by 16% to 163 million tonnes for 99.8 g/km CO₂ per passenger. In 2018, the US airlines had

2520-422: A widebody aircraft smaller than the Boeing 747 yet capable of flying similar long-range routes from airports with shorter runways; this specification would be highly influential in the design of what would become the DC-10. It would become McDonnell Douglas's first commercial airliner after the merger between McDonnell Aircraft Corporation and Douglas Aircraft Company in 1967. An early DC-10 design proposal

2625-416: Is 18.4% to 20.8% of their maximum take-off weight, while single-aisle airliners are between 24.9% and 27.7%. An aircraft weight can be reduced with light-weight materials such as titanium , carbon fiber and other composite plastics if the expense can be recouped over the aircraft's lifetime. Fuel efficiency gains reduce the fuel carried, reducing the take-off weight for a positive feedback . For example,

2730-404: Is 22.9g/ ASK , or 2.86 L/100 km (82 mpg ‑US ) per seat, 3.51 L/100 km (67.0 mpg ‑US ) per passenger at its 81.5% load factor. Fuel economy in air transport comes from the fuel efficiency of the aircraft + engine model, combined with airline efficiency: seating configuration , passenger load factor and air cargo . Over the transatlantic route,

2835-442: Is a trijet , being powered by three turbofan engines. Two of these engines are mounted on pylons that attach to the bottom of the wings, while the third engine is encased in a protective banjo-shaped structure that is mounted on the top of the rear fuselage. In comparison to the first generation of jetliners, these engines generated less noise and were usually smoke-free. The engines are equipped with thrust reversers which reduce

2940-453: Is a low-wing wide-body aircraft . It is sized to conduct medium to long-range flights, offering similar endurance to the larger Boeing 747 yet being able to use shorter runways and thus access airports that it could not. Dependent upon configuration, the main cabin can accommodate between 250 and 380 passengers across its main deck. The fuselage is split into two levels, the upper deck is the only one where passenger seating would be present as

3045-501: Is an American trijet wide-body aircraft manufactured by McDonnell Douglas . The DC-10 was intended to succeed the DC-8 for long- range flights. It first flew on August 29, 1970; it was introduced on August 5, 1971, by American Airlines . The trijet has two turbofans on underwing pylons and a third one at the base of the vertical stabilizer . The twin-aisle layout has a typical seating for 270 in two classes. The initial DC-10-10 had

3150-587: Is an upgrade to add a glass cockpit to the DC-10 with the re-designation to MD-10 . The upgrade included an Advanced Common Flightdeck similar to what was used on the MD-11 and was launched in September 1996. However, the actual avionics are shared with the Boeing 717 , using the Honeywell VIA liquid-crystal-displays. The program was continued by Boeing after its merger with McDonnell Douglas in 1997, and

3255-454: Is attained by minimizing parasitic drag , and lift-generated induced drag , the two components of aerodynamic drag. As parasitic drag increases and induced drag decreases with speed, there is an optimum speed where the sum of both is minimal; this is the best glide ratio . For powered aircraft, the optimum glide ratio has to be balanced with thrust efficiency. Parasitic drag is constituted by form drag and skin-friction drag , and grows with

S-duct - Misplaced Pages Continue

3360-425: Is capable of performing all-weather operations, a function that many preceding jetliners had been incapable of. From the onset, it could perform takeoffs and landings completely under autopilot . Cassette tapes were used to load preprogrammed flight plans into the flight computer. As originally built, the cockpit was operated by a flight crew of three; numerous DC-10s have received a retrofitted glass cockpit and

3465-421: Is determined by the level of efficiency with which thrust can be applied to overcome the aerodynamic drag . A subfield of fluid dynamics , aerodynamics studies the physics of a body moving through the air. As lift and drag are functions of air speed, their relationships are major determinants of an aircraft's design efficiency. Aircraft efficiency is augmented by maximizing lift-to-drag ratio , which

3570-522: Is enabled by ADS-B in oceanic airspace, and the only modification required would be flight control systems software. Comfort would not be affected and trials are limited to two aircraft to reduce complexity but the concept could be expanded to include more. Commercial operations could begin in 2025 with airline schedule adjustments, and other manufacturers' aircraft could be included. While routes are up to 10% longer than necessary, modernized air traffic control systems using ADS-B technology like

3675-665: Is the measure of the transport energy efficiency of aircraft . Fuel efficiency is increased with better aerodynamics and by reducing weight , and with improved engine brake-specific fuel consumption and propulsive efficiency or thrust-specific fuel consumption . Endurance and range can be maximized with the optimum airspeed , and economy is better at optimum altitudes , usually higher. An airline efficiency depends on its fleet fuel burn, seating density, air cargo and passenger load factor , while operational procedures like maintenance and routing can save fuel. Average fuel burn of new aircraft fell 45% from 1968 to 2014,

3780-491: The Airbus A350 design includes a majority of light-weight composite materials. The Boeing 787 Dreamliner was the first airliner with a mostly composite airframe . For long-haul flights , the airplane needs to carry additional fuel, leading to higher fuel consumption. Above a certain distance it becomes more fuel-efficient to make a halfway stop to refuel, despite the energy losses in descent and climb . For example,

3885-511: The Auxiliary power unit (APU), 15 kg (33 lb) with a reduced flap approach and 30 kg (66 lb) with reduced thrust reversal on landing. Maintenance can also save fuel: 100 kg (220 lb) more fuel is consumed without an engine wash schedule; 50 kg (110 lb) with a 5 mm (0.20 in) slat rigging gap, 40 kg (88 lb) with a 10 mm (0.39 in) spoiler rigging gap, and 15 kg (33 lb) with

3990-616: The L-1049 in the 1950s, and from 200 for the DH-106 Comet 3 to 900 for the 1990s B737-800 . Today's turboprop airliners have better fuel-efficiency than current jet airliners, in part because of their propellers . In 2012, turboprop airliner usage was correlated with US regional carriers ' fuel efficiency . Jet airliners became 70% more fuel efficient between 1967 and 2007, 40% due to improvements in engine efficiency and 30% from airframes. Efficiency gains were larger early in

4095-526: The MD-10 with a glass cockpit that eliminated the need for a flight engineer . In February 2014, the DC-10 made its last commercial passenger flight. Cargo airlines continued to operate a small number as freighters . The Orbis Flying Eye Hospital is a DC-10 adapted for eye surgery . A few DC-10s have been converted for aerial firefighting use. Some DC-10s are on display, while other retired aircraft are in storage . Following an unsuccessful proposal for

4200-541: The Royal Netherlands Air Force . These were converted from civil airliners (DC-10-30CF) to a similar standard as the KC-10. Also, commercial refueling companies Omega Aerial Refueling Services and Global Airtanker Service operate three KDC-10 tankers for lease. The DC-10 Air Tanker is a DC-10-based firefighting tanker aircraft, using modified water tanks from Erickson Air-Crane . The MD-10

4305-504: The United States Air Force 's CX-HLS (Heavy Logistics System) in 1965, Douglas Aircraft began design studies based on its CX-HLS submission. The aviation author John H. Fielder notes that the company was under competitive pressure to produce a widebody aircraft, having been somewhat slow in the previous decade to introduce its first jetliners . In 1966, American Airlines offered a specification to manufacturers for

S-duct - Misplaced Pages Continue

4410-707: The United States House of Representatives investigated the cargo-door issue and the certification by the Federal Aviation Administration (FAA) of the original design. An airworthiness directive was issued, and all DC-10s underwent mandatory door modifications. The DC-10 experienced no more major incidents related to its cargo door after FAA-approved changes were made. On May 25, 1979, American Airlines Flight 191 crashed immediately after takeoff from Chicago O'Hare Airport . Its left engine and pylon assembly swung upward over

4515-492: The air freight share for 48%, seating density for 24%, aircraft fuel burn for 16% and passenger load factor for 12%. That same year, Cathay Pacific and Cathay Dragon consumed 4,571,000 tonnes of fuel to transport 123,478 million revenue passenger kilometers , or 37 g/RPK, 25% better than in 1998: 4.63 L/100 km (50.8 mpg ‑US ). Again in 2016, the Aeroflot Group fuel consumption

4620-471: The jet age than later, with a 55-67% gain from 1960 to 1980 and a 20-26% gain from 1980 to 2000. Average fuel burn of new aircraft fell 45% from 1968 to 2014, a compounded annual reduction 1.3% with variable reduction rate. Concorde , a supersonic transport , managed about 17 passenger-miles to the Imperial gallon, which is 16.7 L/100 km per passenger; similar to a business jet, but much worse than

4725-479: The propfan concept for jetliners with an emphasis on engine/airframe efficiency that might come into service beyond the Boeing 787 and Airbus A350 XWB. For instance, Airbus has patented aircraft designs with twin rear-mounted counter-rotating propfans. Propfans bridge the gap between turboprops, losing efficiency beyond Mach 0.5-0.6, and high-bypass turbofans, more efficient beyond Mach 0.8. NASA has conducted an Advanced Turboprop Project (ATP), where they researched

4830-407: The wing aspect ratio or by using wingtip devices at the cost of increased structure weight. By increasing efficiency, a lower cruise-speed augments the range and reduces the environmental impact of aviation ; however, a higher cruise-speed allows more revenue passenger miles flown per day. For supersonic flight, drag increases at Mach 1.0 but decreases again after the transition. With

4935-528: The 1971 estimate of 438 deliveries needed to break even on the program; however, according to Fielder, the DC-10 had not reached the breakeven point by the end of production. As the final DC-10s were delivered, McDonnell Douglas started production of its successor, the MD-11 , which was essentially a stretched derivative of the DC-10-30. In the late 1980s, international travel was on the rise thanks to lower oil prices and more economic freedom , leading to

5040-595: The Advanced Common Flightdeck, which has "significant commonality" with that of the MD-11, thus eliminating the flight engineer and permitting the aircraft, re-designated MD-10 , to be flown by a flight crew of two. Three independent hydraulic systems are present. The flight controls actuate many of the flight control surfaces across the airliner via these hydraulic circuits. The critical nature of these circuits and their vulnerability to damage in

5145-459: The American aerospace company Convair . The legal relationship between McDonnell Douglas, Convair, and the Federal Aviation Administration (FAA) would later serve to complicate matters; specifically, Convair was forbidden from contacting the regulator no matter the severity of any safety concerns it had in the DC-10's design. On February 19, 1968, in what was supposed to be a knockout blow to

5250-579: The Americas, and one with the Panamanian start-up Cargo Three , also in the Americas. Non-airline operators included Omega Aerial Refueling Services with three DC-10 based KDC-10 tanker aircraft , the USAF with its 59 KC-10s, and the 10 Tanker Air Carrier with four modified DC-10-30s used for fighting wildfires. Orbis International has used a DC-10 as a flying eye hospital. Surgery is performed on

5355-598: The Boeing 787 shows a 20% emission savings compared to conventional aluminium airliners, 14-15% fleet-wide when encompassing a fleet penetration below 100%, while the air travel demand would increase due to lower operating costs. Lufthansa , when it ordered both, stated the Airbus A350 -900 and the Boeing 777X -9 will consume an average of 2.9 L/100 km (81 mpg ‑US ) per passenger. The Airbus A321 featuring Sharklet wingtip devices consumes 2.2 L/100 km (110 mpg ‑US ) per person with

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5460-469: The DC-10 achieved a long-term safety record comparable to those of similar-era passenger jets. The DC-10 outsold the similar Lockheed L-1011 TriStar due to the latter's delayed introduction and high cost. Production of the DC-10 ended in 1989, with 386 delivered to airlines along with 60 KC-10 tankers. It was succeeded by the lengthened, heavier McDonnell Douglas MD-11 . After merging with McDonnell Douglas in 1997, Boeing upgraded many in-service DC-10s as

5565-399: The DC-10 had been involved in 55 accidents and incidents , including 32 hull-loss accidents, with 1,261 occupant fatalities. Of these accidents and incidents, it has been involved in nine hijackings resulting in one death and a bombing resulting in 170 occupant fatalities. Despite its poor safety record in the 1970s, which gave it an unfavorable reputation, the DC-10 has proved to be

5670-572: The DC-10's completion in light of the prospective competition and the high financial stakes involved. Together with American Airlines' announcement of the DC-10 order, it was also reported that American Airlines had declared its intention to have the British Rolls-Royce RB211 turbofan engine on its DC-10 airliners. The DC-10 was first ordered by launch customers American Airlines with 25 orders, and United Airlines with 30 orders and 30 options in 1968. The DC-10's similarity to

5775-588: The FAA NextGen or European SESAR could allow more direct routing, but there is resistance from air traffic controllers . Modern jet aircraft have twice the fuel efficiency of the earliest jet airliners . Late 1950s piston airliners like the Lockheed L-1049 Super Constellation and DC-7 were 1% to 28% more energy-intensive than 1990s jet airliners which cruise 40 to 80% faster. The early jet airliners were designed at

5880-607: The L-1011. Further models and derivatives of the DC-10 have been considered; perhaps the most radical of these being an unpursued twin-engined model akin to the Airbus A300 . However, following a spate of fatal accidents, particularly the American Airlines Flight 191 crash (the deadliest aviation accident in US history) orders for the DC-10 had nosedived by 1980, the type having garnered a poor reputation that

5985-560: The Lockheed L-1011 in design, passenger capacity, and launch date resulted in a sales competition that affected the profitability of both aircraft. On August 29, 1970, the first DC-10, a series 10, conducted its maiden flight . An extensive flight test program was carried out, totaling 929 flights and 1,551 flight hours; the test program was not incident-free: during one ground test in 1970, an outwardly-opening cargo door blew out and resulted rapid pressurization changes that caused

6090-529: The United States, and banning all DC-10s from U.S. airspace. These measures were rescinded five weeks later on July 13, 1979, after the slat actuation and position systems were modified, along with stall warning and power supply changes. In November 1979, the FAA fined American Airlines for removing the engine and its pylon as a single unit in its maintenance procedure, thus damaging the structure and causing

6195-489: The advantage of blocking the front of the jet engine from radar. The spinning compressor blades would produce a strong radar return, compared to the smooth sides of the duct. Aircraft built with S-ducts are the: Aircraft previously built with S-ducts, but no longer in production, are the: The Boeing 747-300 Trijet (not to be confused with the later 747-300) was designed with an S-duct layout, but never built. McDonnell Douglas DC-10 The McDonnell Douglas DC-10

6300-453: The airframe and fuel is non-payload that must be lifted to altitude and kept aloft, contributing to fuel consumption. A reduction in airframe weight enables the use of smaller, lighter engines. The weight savings in both allow for a lighter fuel load for a given range and payload. A rule-of-thumb is that a reduction in fuel consumption of about 0.75% results from each 1% reduction in weight. The payload fraction of modern twin-aisle aircraft

6405-415: The amount of energy imparted to the plane per unit of energy in the fuel. The rate at which energy is imparted equals thrust multiplied by airspeed. To get thrust, an aircraft engine is either a shaft engine – piston engine or turboprop , with its efficiency inversely proportional to its brake-specific fuel consumption  – coupled with a propeller having its own propulsive efficiency ; or

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6510-460: The average at 123 g and Lufthansa at 132 g – by using high-density 189-seat Boeing 737-800s . In 2015 Ryanair emitted 8.64 Bn t of CO 2 for 545,034 sectors flown: 15.85 t per 776 miles (674 nmi; 1,249 km) average sector (or 5.04 t of fuel: 4.04 kg/km) representing 95 kg per 90.6 million passengers (30.4 kg of fuel: 3.04 L/100 km or 76 g CO 2 /km). In 2016, over

6615-415: The cargo door design to be dangerously flawed, as the door could be closed without the locking mechanism fully engaged, and this condition was not apparent from visual inspection of the door nor from the cargo-door indicator in the cockpit. The NTSB recommended modifications to make it readily apparent to baggage handlers when the door was not secured and also recommended adding vents to the cabin floor so that

6720-499: The cargo door, but the basic design remained unchanged, and problems persisted. On March 3, 1974, in an accident circumstantially similar to American Airlines Flight 96, a cargo-door blowout caused Turkish Airlines Flight 981 to crash near Ermenonville , France, in the deadliest air crash in history at the time—346 passengers and crew died. The cargo door of Flight 981 had not been fully locked, though it appeared so to both cockpit crew and ground personnel. The Turkish aircraft had

6825-423: The competing Lockheed L-1011 , George A. Spater , President of American Airlines, and James S. McDonnell of McDonnell Douglas announced American Airlines' intention to acquire the DC-10. This was a shock to Lockheed and there was general agreement within the U.S. aviation industry that American Airlines had left its competitors at the starting gate. According to Fielder, McDonnell Douglas had been urgently pursuing

6930-436: The continued use of smaller engines in the 15–30 kN (3,400–6,700 lb f ) class with which Falcons have historically been designed. In international aviation regulations the triple engine layout is also considered inherently safer for the increased redundancy, which allows the use of certain airfields at high elevation only for aircraft with more than two engines. The S-duct is also used on combat aircraft, where it has

7035-647: The conversions. On January 8, 2007, Northwest Airlines retired its last remaining DC-10 from scheduled passenger service, thus ending the aircraft's operations with major airlines. Regarding the retirement of Northwest's DC-10 fleet, Wade Blaufuss, spokesman for the Northwest chapter of the Air Line Pilots Association said, "The DC-10 is a reliable airplane, fun to fly, roomy and quiet, kind of like flying an old Cadillac Fleetwood . We're sad to see an old friend go." Biman Bangladesh Airlines

7140-514: The crash of American Airlines Flight 191 , the deadliest aviation accident in U.S. history, the U.S. Federal Aviation Administration (FAA) temporarily banned all DC-10s from American airspace in June 1979. In August 1983, McDonnell Douglas announced that production would end due to a lack of orders, as it had widespread public apprehension after the 1979 crash and a poor fuel economy reputation. As design flaws were rectified and fleet hours increased,

7245-405: The critical fiscal factor is the quantity of fuel burnt per seat-nautical mile. For these reasons, the world's longest commercial flights were cancelled c.  2013 . An example is Singapore Airlines' former New York to Singapore flight, which could carry only 100 passengers (all business class) on the 10,300-mile (16,600 km) flight. According to an industry analyst, "It [was] pretty much

7350-503: The design of the L-1011 indicated that losses of using an S-duct were more than compensated for by the savings. The S-shaped duct is a complicated and costly design. Since modern jet engines have more power and reliability than those of the 1970s and can safely power the aircraft with only two engines, the trijet design is no longer used for large commercial airliners but is used on the latest Dassault Falcon 7X and Falcon 8X business jets in order to provide more total thrust while enabling

7455-454: The distance required when landing. Despite being considerably larger, the landing speed of the DC-10 was comparable to that of the contemporary Boeing 727 . The primary flight controls of the DC-10 consist of inboard and outboard ailerons , two-section elevators , and a two-section rudder ; the secondary flight controls comprise leading edge slats , spoilers , and a dual-rate movable horizontal stabilizer . The vertical stabilizer with

7560-496: The door appeared secure, but the internal locking mechanism was not fully engaged. When the aircraft reached approximately 11,750 feet (3,580 m) in altitude, the door blew out, and the resulting explosive decompression collapsed the cabin floor. Many control cables to the empennage were cut, leaving the pilots with very limited control of the aircraft. Despite this, the crew performed a safe emergency landing. U.S. National Transportation Safety Board (NTSB) investigators found

7665-428: The doors do not occupy otherwise usable interior space when open. To overcome the outward force from pressurization of the fuselage at high altitudes, outward-opening doors must use heavy locking mechanisms. In the event of a door lock malfunction, there is greater potential for explosive decompression . On June 12, 1972, American Airlines Flight 96 lost its aft cargo door above Windsor, Ontario . Before takeoff,

7770-409: The engine separation, rather than removing the engine from the pylon before removing the pylon from the wing as advised by McDonnell Douglas. On July 19, 1989, United Airlines Flight 232 crashed at Sioux City, Iowa , after an uncontained engine failure of the tail engine earlier in the flight disabled all hydraulic systems and rendered most flight controls inoperable. The flight crew, assisted by

7875-564: The first MD-10 flew on April 14, 1999. The new cockpit eliminated the need for the flight engineer position and allowed common type rating with the MD-11. This has allowed companies such as FedEx Express , which operated both the MD-10 and MD-11, to use a common pilot pool for both aircraft. The MD-10 conversion now falls under the Boeing Converted Freighter program where Boeing's international affiliate companies perform

7980-621: The fuel used for takeoff is relatively large compared to the amount expended in the cruise segment, and because less fuel-efficient regional jets are typically used on shorter flights. New technology can reduce engine fuel consumption, like higher pressure and bypass ratios , geared turbofans , open rotors , hybrid electric or fully electric propulsion ; and airframe efficiency with retrofits, better materials and systems and advanced aerodynamics. A powered aircraft counters its weight through aerodynamic lift and counters its aerodynamic drag with thrust . The aircraft's maximum range

8085-597: The ground and the operating room is located between the wings for maximum stability. In 2008, Orbis replaced its aging DC-10-10 with a DC-10-30 jointly donated by FedEx and United Airlines. The newer DC-10 was converted into an MD-10 configuration and began flying as an eye hospital in 2010. A modified DC-10 is operated by the Missile Defense Agency as the Widebody Airborne Sensor Platform (WASP). As of September 2015,

8190-424: The initial flight being a round-trip flight between Los Angeles and Chicago. United Airlines also commenced DC-10 flights later that same month. American's DC-10s were configured to seat a maximum of 206 passengers while United's seated 222; both had six-across seating in first-class and eight-across (four pairs) in coach. They operated the first version of the DC-10, referred to as the "domestic" series 10, which had

8295-516: The lowest carbon footprint with 1.4 kg (3 lb) of fuel per seat per 100 km, equivalent to 1.75 L/100 km [134 mpg ‑US ] per seat. Continuous Descent Approaches can reduce emissions. Beyond single-engine taxi , electric taxiing could allow taxiing on APU power alone, with the main engines shut down, to lower the fuel burn. Airbus presented the following measures to save fuel, in its example of an Airbus A330 flying 2,500 nautical miles (4,600 km) on

8400-408: The main cabin's floor to collapse. This discovery and first effort at rectification led to a contract dispute between McDonnell Douglas and Convair over what changes were necessary and financial liability. Fielder alleges that McDonnell Douglas consistently sought to minimize and postpone any design changes to the DC-10, although this attitude was not an explicit policy. In July 1971, Convair outlined

8505-480: The maximum range speed is when the ratio between velocity and drag is minimal, while maximum endurance is attained at the best lift-to-drag ratio. Air density decreases with altitude, thus lowering drag, assuming the aircraft maintains a constant equivalent airspeed . However, air pressure and temperature both decrease with altitude, causing the maximum power or thrust of aircraft engines to reduce. To minimize fuel consumption, an aircraft should cruise close to

8610-463: The maximum altitude at which it can generate sufficient lift to maintain its altitude. As the aircraft's weight decreases throughout the flight, due to fuel burn, its optimum cruising altitude increases. In a piston engine , the decrease in pressure at higher altitudes can be mitigated by the installation of a turbocharger . Decreasing temperature at higher altitudes increases thermal efficiency . Since early 2006 until 2008, Scandinavian Airlines

8715-403: The models is that the series 10 has three sets of landing gear (one front and two main) while the series 30 and 40 have an additional centerline main gear. The center main two-wheel landing gear (which extends from the center of the fuselage) was added to distribute the extra weight and for additional braking. The series 30 had a typical load range of 6,220 miles (5,410 nmi; 10,010 km) and

8820-427: The most from winglets. They average a 6.69% increase in efficiency but depending on the route have a fuel savings distribution spanning from 4.6% to 10.5%. Airbus A319s see the most consistent fuel and emissions savings from winglets. Airbus A321s average a 4.8% improvement in fuel consumption, but have the widest swing based on routes and individual aircraft, recognizing anywhere from 0.2% improvement to 10.75%. As

8925-403: The most-active intercontinental market, the average fuel consumption in 2017 was 34 pax-km per L (2.94 L/100 km [80 mpg ‑US ] per passenger). The most fuel-efficient airline was Norwegian Air Shuttle with 44 pax-km/L (2.27 L/100 km [104 mpg ‑US ] per passenger), thanks to its fuel-efficient Boeing 787 -8, a high 85% passenger load factor and

9030-531: The plans for the DC-10-50 were abandoned after British Airways ordered the Lockheed L-1011-500 instead. Beginning in 1966, two-engine designs were studied for the DC-10 before the design settled on the three-engine configuration. Later, a big twin based on the DC-10 cross-section was proposed to Airbus as a 50/50 venture but was rejected. Then in 1971, a shortened DC-10 version with two engines

9135-434: The pressure difference between the cabin and cargo bay during decompression could quickly equalize without causing further damage. Although many carriers voluntarily modified the cargo doors, no airworthiness directive was issued, due to a gentlemen's agreement between the head of the FAA, John H. Shaffer , and the head of McDonnell Douglas's aircraft division, Jackson McGowen. McDonnell Douglas made some modifications to

9240-412: The rudder is mounted on top of the tail engine banjo while the horizontal stabilizer with its four-segment elevator is attached to the sides of the rear fuselage conventionally. The DC-10 is equipped with retractable tricycle landing gear . To enable higher gross weights, the later –30 and –40 series have an additional two-wheel main landing gear, which retracts into the center of the fuselage. The DC-10

9345-524: The series 10 and 30 engines were General Electric CF6 . Prior to taking delivery of the aircraft, Northwest's president asked that the "series 20" aircraft be redesignated "series 40" because the airliner was much improved over the original design. The FAA issued the certification for the series 40 on October 27, 1972. In 1972, the DC-10's listed unit cost was reportedly US$ 20M ($ 146 million in 2023 prices). The series 30 and 40 were longer-range "international" versions. The main visible difference between

9450-417: The situation in a formal memo; almost a year later, it internally expressed concerns that the inadequate resolution would lead to loss of aircraft. Tragically, the initial rectification work would prove to be inadequate. On July 29, 1971, the FAA issued the type certificate for the DC-10, permitting its entry into revenue service. It entered commercial service with American Airlines on August 5, 1971, with

9555-404: The smaller lower level is typically used for storage for baggage and food preparation; elevators are usually present to carry people and carts between the two levels. As originally designed, the floor of the main cabin was not strong enough to withstand full pressure differential, yet key control lines are routed through this floor, an approach that proved to be a key vulnerability. The DC-10

9660-405: The square of the speed in the drag equation . The form drag is minimized by having the smallest frontal area and by streamlining the aircraft for a low drag coefficient , while skin friction is proportional to the body's surface area, and can be reduced by maximizing laminar flow . Induced drag can be reduced by decreasing the size of the airframe , fuel and payload weight, and by increasing

9765-531: The straight-through design on the DC-10 and MD-11, the S-duct allows a shorter fin and a rudder closer to the longitudinal axis. On the Lockheed L-1011 TriStar , engineers were able to maintain engine performance comparable with straight-through designs by limiting the curve of the S-duct to less than a quarter of the radius of the engine intake diameter. The S-duct design also reduced the total empty aircraft weight. The research undertaken during

9870-500: The tail area led to the addition of hydraulic fuses to prevent the total loss of fluid. Power for the hydraulics was derived from primary and reserve engine-driven pumps equipped on each of the three engines. Hydraulic power was required for flight control, there was no provision for reverting to manual flight control inputs. A proposed version of the DC-10-10 with extra fuel tanks, 3 feet (91 cm) extensions on each wingtip, and

9975-580: The tail engine, the engine failure ruptured all three, resulting in a total loss of control of the elevators, ailerons, spoilers, horizontal stabilizers, rudder, flaps, and slats. Following the accident, hydraulic fuses were installed in the #3 hydraulic system below the tail engine on all DC-10 aircraft to ensure that sufficient control remains if all three hydraulic systems are damaged in this area. Related development Aircraft of comparable role, configuration, and era Related lists Fuel economy in aircraft The fuel economy in aircraft

10080-524: The top of the wing, severing the leading edge slat actuator hydraulic lines. The slats retracted under the aerodynamic forces , causing the left wing to stall . This, combined with asymmetric thrust due to the missing engine, caused the aircraft to rapidly roll to the left, descend, and crash, killing all 271 people on board and two on the ground. Following the crash, the FAA withdrew the DC-10's type certificate on June 6, 1979, grounding all U.S.-registered DC-10s and those from nations with agreements with

10185-456: The trans pacific routes, the average fuel consumption was 31 pax-km per L (3.23 L/100 km [73 mpg ‑US ] per passenger). The most fuel-efficient were Hainan Airlines and ANA with 36 pax-km/L (2.78 L/100 km [85 mpg ‑US ] per passenger) while Qantas was the least efficient at 22 pax-km/L (4.55 L/100 km [51.7 mpg ‑US ] per passenger). Key drivers for efficiency were

10290-435: The weight indirectly generates lift-induced drag, its minimization leads to better aircraft efficiency. For a given payload, a lighter airframe generates a lower drag. Minimizing weight can be achieved through the airframe's configuration, materials science and construction methods. To obtain a longer range, a larger fuel fraction of the maximum takeoff weight is needed, adversely affecting efficiency. The deadweight of

10395-729: The wingspan. (Wingspan is limited by the available width in the ICAO Aerodrome Reference Code .) Airbus installed wingtip fences on its planes since the A310-300 in 1985, and Sharklet blended-winglets for the A320 were launched during the November 2009 Dubai Airshow . Their installation adds 200 kilograms (440 lb) but offers a 3.5% fuel burn reduction on flights over 2,800 km (1,500 nmi). On average, among large commercial jets, Boeing 737-800s benefit

10500-445: Was flying slower, from 860 to 780 km/h, to save on fuel costs and curb emissions of carbon dioxide. From 2010 to 2012, the most fuel-efficient US domestic airline was Alaska Airlines , due partly to its regional affiliate Horizon Air flying turboprops. In 2014, MSCI ranked Ryanair as the lowest-emissions-intensity airline in its ACWI index with 75 g CO 2 -e/ revenue passenger kilometre – below Easyjet at 82 g,

10605-504: Was for a four-engine double-deck wide-body jet airliner with a maximum seating capacity of 550 passengers and similar in length to a DC-8 . The proposal was shelved in favor of a trijet single-deck wide-body airliner with a maximum seating capacity of 399 passengers, and similar in length to the DC-8 Super 60. Large portions of the detailed design work, particularly that of the fuselage, were subcontracted to external companies, such as

10710-461: Was primarily operated by the United States Air Force . Early operations of the DC-10 were afflicted by its poor safety record, which was partially attributable to a design flaw in the original cargo doors that caused multiple incidents, including fatalities. Most notable was the crash of Turkish Airlines Flight 981 in Paris in 1974, the deadliest crash in aviation history up to that time. Following

10815-424: Was proposed as a competitor to the Airbus A300 . McDonnell Douglas held a major presentation of the proposed DC-10 Twin at Long Beach, and several European airlines were willing to place orders. However on July 30, 1973, MDC's board decided not to give the proposed twin the go-ahead, as no US airline had ordered it. Later, more DC-10 Twin proposals were made, either as a collaboration with a European manufacturer or as

10920-486: Was the last commercial carrier to operate the DC-10 in passenger service. The airline flew the DC-10 on a regular passenger flight for the last time on February 20, 2014, from Dhaka , Bangladesh to Birmingham , UK. Local charter flights were flown in the UK until February 24, 2014. As of September 2024, two DC-10s are in commercial service, one with TAB Airlines , a Bolivian cargo airline operating scheduled flights in

11025-554: Was widespread amongst the traveling public as well as prospective operators. Competitive pressure had also played a role, Boeing in particular had developed the 747SP variant specifically to better compete with the DC-10 and L-1011. In December 1988, the 446th and final DC-10 rolled off the Long Beach, California Products Division production line and was delivered to Nigeria Airways in July 1989. The production run had exceeded

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