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Wide–body three–engine airliner From Wikipedia, the free encyclopedia
The McDonnell Douglas DC-10 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.
DC-10 / MD-10 | |
---|---|
General information | |
Type | Wide-body airliner |
National origin | United States |
Manufacturer | McDonnell Douglas |
Status | In limited non-passenger service |
Primary users | FedEx Express (historical)
|
Number built | 386[1] |
History | |
Manufactured | 1969–1989 |
Introduction date | August 5, 1971, with American Airlines |
First flight | August 29, 1970 |
Retired | 2014 (passenger service) |
Variants | |
Developed into | McDonnell Douglas MD-11 |
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 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 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 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.[2] As design flaws were rectified and fleet hours increased, 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 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 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.[3][4] In 1966, American Airlines offered a specification to manufacturers for 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.[5] It would become McDonnell Douglas's first commercial airliner after the merger between McDonnell Aircraft Corporation and Douglas Aircraft Company in 1967.[6][7]
An early DC-10 design proposal 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.[8] Large portions of the detailed design work, particularly that of the fuselage, were subcontracted to external companies, such as the American aerospace company Convair.[9] 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.[10]
On February 19, 1968, in what was supposed to be a knockout blow to 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 the DC-10's completion in light of the prospective competition and the high financial stakes involved.[11] 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.[12] 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.[13][14][15] The DC-10's similarity to the Lockheed L-1011 in design, passenger capacity, and launch date resulted in a sales competition that affected the profitability of both aircraft.[16]
On August 29, 1970, the first DC-10, a series 10, conducted its maiden flight.[17] 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 the main cabin's floor to collapse.[18][19] 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.[20] In July 1971, Convair outlined the situation in a formal memo; almost a year later, it internally expressed concerns that the inadequate resolution would lead to loss of aircraft.[21] Tragically, the initial rectification work would prove to be inadequate.[22]
On July 29, 1971, the FAA issued the type certificate for the DC-10, permitting its entry into revenue service.[19] It entered commercial service with American Airlines on August 5, 1971, with the initial flight being a round-trip flight between Los Angeles and Chicago. United Airlines also commenced DC-10 flights later that same month.[23] 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.[24] They operated the first version of the DC-10, referred to as the "domestic" series 10, which had 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).[25][26] The series 20 was powered by Pratt & Whitney JT9D turbofan engines, whereas 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.[27][7] In 1972, the DC-10's listed unit cost was reportedly US$20M[28] ($146 million in 2023 prices).
The series 30 and 40 were longer-range "international" versions. The main visible difference between 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 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).[25][29]
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, 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.[30][31] 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 was widespread amongst the traveling public as well as prospective operators.[2][32] 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.[33]
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.[34][35] The production run had exceeded the 1971 estimate of 438 deliveries needed to break even on the program;[36] however, according to Fielder, the DC-10 had not reached the breakeven point by the end of production.[11] 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.[37][38]
In the late 1980s, international travel was on the rise thanks to lower oil prices and more economic freedom, leading to 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.[39]
The McDonnell Douglas DC-10 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.[40] 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 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.[41][40] As originally designed, the floor of the main cabin was not strong enough to withstand full pressure differential,[42] yet key control lines are routed through this floor, an approach that proved to be a key vulnerability.[20]
The DC-10 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.[40] In comparison to the first generation of jetliners, these engines generated less noise and were usually smoke-free.[43] The engines are equipped with thrust reversers which reduce the distance required when landing.[44] Despite being considerably larger, the landing speed of the DC-10 was comparable to that of the contemporary Boeing 727.[45]
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.[46] The vertical stabilizer with 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.[47]
The DC-10 is capable of performing all-weather operations, a function that many preceding jetliners had been incapable of.[44] 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.[48] As originally built, the cockpit was operated by a flight crew of three;[44] numerous DC-10s have received a retrofitted glass cockpit and 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.[49][50] Three independent hydraulic systems are present.[51] The flight controls actuate many of the flight control surfaces across the airliner via these hydraulic circuits.[43] The critical nature of these circuits and their vulnerability to damage in the tail area led to the addition of hydraulic fuses to prevent the total loss of fluid.[52] 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.[53]
A proposed version of the DC-10-10 with extra fuel tanks, 3 feet (91 cm) extensions on each wingtip, and 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.[65] Northwest Orient Airlines, one of the launch customers for this longer-range DC-10 requested the name change to DC-10-40.[62]
A proposed version with Rolls-Royce RB211-524 engines for British Airways. The order never came and the plans for the DC-10-50 were abandoned after British Airways ordered the Lockheed L-1011-500 instead.[67]
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 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 a solely McDonnell Douglas product, but none proceeded beyond design studies.[68][69]
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.[70] These aircraft are powered exclusively by General Electric CF6 turbofan engines.
The KDC-10 was an aerial refueling tanker for 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[71][72] and Global Airtanker Service[73][74] 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 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.[49] 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 the first MD-10 flew on April 14, 1999.[75] 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 the conversions.[76]
On January 8, 2007, Northwest Airlines retired its last remaining DC-10 from scheduled passenger service,[78] 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."[79] Biman Bangladesh Airlines was the last commercial carrier to operate the DC-10 in passenger service.[80][81][82] 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.[81][83] Local charter flights were flown in the UK until February 24, 2014.[84] As of September 2024, two DC-10s are in commercial service, one with TAB Airlines, a Bolivian cargo airline operating scheduled flights in the Americas, and one with the Panamanian start-up Cargo Three, also in the Americas.[citation needed]
Non-airline operators included Omega Aerial Refueling Services with three DC-10 based KDC-10 tanker aircraft and the 10 Tanker Air Carrier with four modified DC-10-30s used for fighting wildfires.[85] Orbis International has used a DC-10 as a flying eye hospital. Surgery is performed on 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.[86][87] The newer DC-10 was converted into an MD-10 configuration and began flying as an eye hospital in 2010.[87][88][89] A modified DC-10 is operated by the Missile Defense Agency as the Widebody Airborne Sensor Platform (WASP).[90]
As of September 2015, the DC-10 had been involved in 55 accidents and incidents,[91] including 32 hull-loss accidents,[92] with 1,261 occupant fatalities.[93] Of these accidents and incidents, it has been involved in nine hijackings resulting in one death and a bombing resulting in 170 occupant fatalities.[93] Despite its poor safety record in the 1970s, which gave it an unfavorable reputation,[94] the DC-10 has proved to be a reliable aircraft with a low overall accident rate as of 1998.[95] The DC-10's initially poor safety record has continuously improved as design flaws were rectified and fleet hours increased.[95] The DC-10's lifetime safety record is comparable to similar second-generation passenger jets as of 2008.[96]
The DC-10 has cargo doors that open outward; this allows the cargo area to be completely filled, as 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.[97]
On June 12, 1972, American Airlines Flight 96 lost its aft cargo door above Windsor, Ontario. Before takeoff, 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.[98] Many control cables to the empennage were cut, leaving the pilots with very limited control of the aircraft.[99][100] Despite this, the crew performed a safe emergency landing.[101] U.S. National Transportation Safety Board (NTSB) investigators found 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 the pressure difference between the cabin and cargo bay during decompression could quickly equalize without causing further damage.[98][102] 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.[103] McDonnell Douglas made some modifications to the cargo door, but the basic design remained unchanged, and problems persisted.[98][104]
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,[98][105] in the deadliest air crash in history at the time—346 passengers and crew died.[106] 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 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.[98] 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.[107] Following this crash, a special subcommittee of the United States House of Representatives investigated the cargo-door issue and the certification by the Federal Aviation Administration (FAA) of the original design.[108] An airworthiness directive was issued, and all DC-10s underwent mandatory door modifications.[108] The DC-10 experienced no more major incidents related to its cargo door after FAA-approved changes were made.[98]
On May 25, 1979, American Airlines Flight 191 crashed immediately after takeoff from Chicago O'Hare Airport.[109] Its left engine and pylon assembly swung upward over 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.[110] 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 the United States, and banning all DC-10s from U.S. airspace.[111][112] 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.[113][114] 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 the engine separation, rather than removing the engine from the pylon before removing the pylon from the wing as advised by McDonnell Douglas.[113][109]
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 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.[115] 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 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.[115][52] 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.[116][117]
Variant | -10 | -30 | -40 | |
---|---|---|---|---|
Cockpit crew | Three | |||
Std. seating | 270 (222Y 8-abreast @ 34" + 48J 6-abreast @ 38") | |||
Max. seating | 399Y (10-abreast @ 29–34" pitch) layout, FAA exit limit: 380[148] | |||
Cargo | 26 LD3 layout, main deck: 22 88×125″ or 30 88×108″ pallets | |||
Length | 182 ft 3.1 in / 55.55 m | 181 ft 7.2 in / 55.35 m | 182 ft 2.6 in / 55.54 m | |
Height | 57 ft 6 in / 17.53 m | 57 ft 7 in / 17.55 m | ||
Wingspan | 155 ft 4 in / 47.35 m | 165 ft 4 in / 50.39 m | ||
Wing area[149] | 3,550 sq ft (330 m2) | 3,647 sq ft (338.8 m2) | ||
Width | 19 ft 9 in (6.02 m) fuselage, 224 in (569 cm) interior | |||
OEW (pax) | 240,171 lb / 108,940 kg | 266,191 lb / 120,742 kg | 270,213 lb / 122,567 kg | |
MTOW | 430,000 lb / 195,045 kg | 555,000 lb / 251,744 kg | ||
Max. payload | 94,829 lb / 43,014 kg | 101,809 lb / 46,180 kg | 97,787 lb 44,356 kg | |
Fuel capacity | 21,762 US gal / 82,376 L | 36,652 US gal / 137,509 L | ||
Engines ×3 | GE CF6-6D | GE CF6-50C | PW JT9D-20 / -59A | |
Thrust ×3[149] | 40,000 lbf / 177.92 kN | 51,000 lbf / 226.85 kN | 53,000 lbf / 235.74 kN | |
Cruise | Mach 0.82 (473 kn; 876 km/h; 544 mph) typical, Mach 0.88 (507 kn; 940 km/h; 584 mph) MMo[148] | |||
Range[a] | 3,500 nmi (6,500 km; 4,000 mi) | 5,200 nmi (9,600 km; 6,000 mi) | 5,100 nmi (9,400 km; 5,900 mi) | |
Takeoff[b] | 9,000 ft (2,700 m) | 10,500 ft (3,200 m) | 9,500 ft (2,900 m) | |
Ceiling | 42,000 ft (12,800 m)[148] |
1971 | 1972 | 1973 | 1974 | 1975 | 1976 | 1977 | 1978 | 1979 | 1980 | 1981 | 1982 | 1983 | 1984 | 1985 | 1986 | 1987 | 1988 | 1989 | Total |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
13 | 52 | 57 | 48 | 42 | 19 | 14 | 18 | 36 | 40 | 25 | 11 | 12 | 10 | 11 | 17 | 10 | 10 | 1 | 446 |
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