Editing Lockheed L-1011 TriStar (section)

==Variants==
{{More citations needed section|date=September 2010}}

The earlier versions of the L-1011, such as the -1, -100, and -150 can be distinguished from the later models by the design of the middle engine nacelles. The earlier version nacelle has a round intake, whereas the later models have a small vertical fin between the bottom of the middle engine intake and the top of the fuselage.

The two L-1011 aircraft delivered to [[Pacific Southwest Airlines]] were configured with internal [[airstair]] doors that led into an entry hall in what was normally the forward lower baggage hold. This was to allow operations from airfields that did not have terminal buildings with [[jet bridge]]s. These two aircraft were later in service with [[Aeroperú]] and [[Worldways Canada]].

===L-1011-1===
[[File:Thai Sky Airlines L-1011-1 HS-AXA HKG 2005-3-20.png|thumb|A [[Thai Sky Airlines]] L-1011-1 at [[Hong Kong International Airport]] in 2005]]

The L-1011-1 (FAA certification L-1011-385-1) was the first production model of the L-1011, designed for short- and medium-range flights. This variant served as the basis for subsequent variants. This type was purchased by Air Canada, ANA, Cathay Pacific, Eastern, and other operators with regional trunk routes requiring a widebody aircraft. Pacific Southwest Airlines purchased two L-1011-1 models with lower deck seating.<ref>{{cite web |url= http://www.usairways.com/en-US/aboutus/pressroom/history/psa.html |title= US Airways History |publisher =US Airways |access-date= July 16, 2011}}</ref> This variant was also one of the few widebodies to have the option for a full-height built-in [[airstair]].<ref name=David_Encyclo/>

The L-1011-1 was first delivered to Eastern Air Lines on April 5, 1972. A total of 160 L-1011-1 TriStars were built before production ended in 1983, although the majority of these, 119 or 75% of the total, were completed during a four-year period from 1972 to 1975. Most sales of the L-1011-1 were to US operators, with just three airlines, Delta, Eastern, and TWA, taking delivery of 110 combined. A further two aircraft were placed with a fourth US airline, Pacific Southwest Airlines.<ref name=David_Encyclo/>

===L-1011-100===
[[File:Trans World Airlines Lockheed L-1011-385-1-15 TriStar 100 Marmet.jpg|thumb|[[Trans World Airlines]] L-1011-100 TriStar]]

The L-1011-100 (FAA certification L-1011-385-1-14) was the second production model of the L-1011 and first flew in 1975 and featured a new center fuel tank and higher gross weights that increased the aircraft's range by nearly {{convert|930|mi|km}}. Launch orders for the L-1011-100 were placed by [[Saudia]] and [[Cathay Pacific]], for two each, in May 1974. Deliveries began in June 1975.

The variant was also purchased by several airlines with longer-range routes, such as TWA, Air Canada, and [[British European Airways|BEA]] (which merged with [[British Overseas Airways Corporation|BOAC]] to form [[British Airways]]). The first two L-1011-100s (serial numbers 1110 and 1116) were delivered new to [[Saudia]] with the same fuel capacity as the L-1011-1 (FAA certification L-1011-385-1-14); these were later upgraded to L-1011-200 specification.

===L-1011-50===
The L-1011-50 was an upgraded version of the L-1011-1 with an increase in maximum takeoff weight from {{convert|430,000|lb|kg|sigfig=3}} to either {{convert|440,000|lb|kg|sigfig=3}} or {{convert|450,000|lb|kg|sigfig=3}}. Fuel capacity was not increased. The -50 was available only as a conversion package for the L-1011-1 and was never built new.

===L-1011-150===
The L-1011-150 was a development of the L-1011-1 with its maximum takeoff weight increased to {{convert|470000|lb|kg}}. It was available only as a conversion for the L-1011-1. The -150 involves the conversion of Group 1 and Group 2 L-1011-1 aircraft to an MTOW of {{convert|470000|lb|kg}}, an increase of {{convert|40000|lb|kg}}, about 10%, from the L-1011-1, giving the aircraft a slightly better range than the -50, but without the additional center-section fuel tank, less than the L-1011-100 aircraft.  The first aircraft was converted by [[Messerschmitt-Bölkow-Blohm|MBB]] at Lemwerder in Germany during the winter of 1988–89 and was subsequently handed over to [[Air Transat]] of Canada on May 11, 1989.

===L-1011-200===
[[File:Saudi Arabian Airlines L-1011-200 HZ-AHE LHR 1985-5-17.png|thumb|A [[Saudia]] L-1011-200 TriStar at [[London Heathrow Airport]], 1985]]

The L-1011-200 (FAA certification L-1011-385-1-15), the third production model of the L-1011, was introduced in 1976. Although otherwise similar to the -100, the -200 uses [[Rolls-Royce RB.211]]-524B engines to improve its performance in hot and high-altitude conditions. Gulf Air used -200 models to replace its earlier-generation [[Vickers VC10]] fleet.

Other than the engines, the basic TriStar -200 is identical to the -100, with center-section fuel, having a MTOW of {{convert|466000|lb|kg}}, and fuel capacity of {{convert|26400|usgal|L}} as the -100. An increase of gross weight to {{convert|474000|lb|kg}} is possible, with the heavier aircraft offered by Lockheed as -200I or -200(Improved).  [[Saudi Arabian Airlines]] (Saudia) was a launch customer for the -200 series and operated a sizable fleet until 1998. A total of 24 L-1011-200 aircraft were built new, with the first delivered to Saudia on May 28, 1977. Like other TriStar improvements, a conversion program has also been offered.

===L-1011-250===
The L-1011-250 was an upgrade developed for late-model L-1011-1 aircraft and all L-1011-100 and L-1011-200 aircraft. The more powerful engines, lengthened wing, active-load-control ailerons and other systems that had been developed for the L-1011-500 were adapted into the baseline model.  The changes resulted in increases in maximum takeoff weight to {{convert|510000|lb|kg}} and fuel capacity from 23,600&nbsp;US gal (89,335&nbsp;L) to 31,632&nbsp;US gal (119,735&nbsp;L). This variant also used the upgraded [[Rolls-Royce RB211|RB211-524B4I]] engine, which could be easily retrofitted to the existing [[Rolls-Royce RB211|RB211-524B]] powerplants of the L-1011-200, but it required a re-engining on the L-1011-1 and L-1011-100, which used the original RB211-22B. The conversion allowed the L-1011 to match the performance of the long-range McDonnell Douglas DC-10-30. Although it could be applied to all L-1011 models, the upgrade was only undertaken by Delta on six late-model L-1011-1 aircraft.

===L-1011-500===
[[File:Lockheed L-1011-385-3 TriStar 500, TAP Air Portugal AN0206508.jpg|thumb|A [[TAP Air Portugal]] L-1011-500 in 1990]]

The L-1011-500 (FAA certification L-1011-385-3) was the last L-1011 variant to enter production. It was a longer-range variant first flight-tested in 1978. Its fuselage length was shortened by {{convert|14|ft|m}} and MTOW increased to allow higher fuel loads.{{citation needed|date=October 2013}} More powerful RB.211-524 engines, increased wingspan, active-load-control ailerons and other improved systems were features introduced by Lockheed to exploit newly available technologies in the late 1970s. The -500 variant was popular among international operators and formed a significant portion of the L-1011 fleet of Delta and British Airways. However, it entered service seven years after the similar [[McDonnell Douglas DC-10#Longer-range variants|DC-10-30]] entered service.{{Cn|date=September 2024}}

[[File:Lockheed L1011-500 Tristar approaching Gatwick runway 08R - geograph.org.uk - 6430300.jpg|thumb|A [[Luzair]] L1011-500 Tri Star while on approach to [[Gatwick Airport]].]]
The TriStar 500 first flew on October 16, 1978, with the first delivery to British Airways on April 27, 1979. It entered service with British Airways on May 7, 1979, flying between London and Abu Dhabi. The last L-1011 produced was a TriStar 500, operated by the Las Vegas Sands.{{Cn|date=September 2024}}

====Dimensions====
The TriStar 500 has an overall length of {{convert|164|ft|2|in|m|2}} and wingspan increased to {{convert|164|ft|4|in|m|2}} (early TriStar versions originally had the TriStar 1 wing with a span of {{convert|155|ft|4|in|m|2}}). 

====Flying surfaces====
Lockheed developed some aerodynamic improvements for the TriStar 500 which included a modified wing-to-body fairing, a fillet below the central intake, extended wingtips, and "active ailerons" or active control system (ACS). The new fairing reduced drag, while the fillet reduced noise in the rear cabin. The wingtip extensions increased aspect ratio, thus reducing induced drag, but resulted in increased bending. The ACS developed to solve this, provided gust alleviation, improving ride during flight, reduced fuel burn, and increased fatigue life.

Earlier TriStar 500s were delivered with the standard wing; these were later retrofitted with ailerons and extended wingtips. Pan Am was the first customer to order the -500 with the extended wingtips and active ailerons. Aircraft serial number 1176, the first for Pan Am, was the first TriStar 500 to be fitted with them as standard.

====Powerplant====
[[File:Lockheed L-1011-385-3 TriStar 500, AirLanka AN0962210.jpg|thumb|An [[SriLankan Airlines|Air Lanka]] L-1011-500 TriStar ferrying an extra engine.]]

The TriStar 500 is equipped with the more powerful RB211-524B engines. Initially rated at {{convert|50000|lbf|kN|abbr=on}} thrust each, the higher-thrust {{convert|53000|lbf|kN|abbr=on}} -524B4 Improved (also referred to as the -524B4I) later became available, which also offered improved [[fuel efficiency]].

====Performance====
Originally certified with an MTOW of {{convert|496000|lb|kg}}, an increased MTOW of {{convert|504000|lb|kg}} was later certified in 1979, and all earlier production aircraft were certified at this weight. A further increase, to {{convert|510000|lb|kg}}, is also available, and most TriStar 500s are thought to have had this increase. Standard fuel capacity is {{convert|31600|USgal|L}}, giving the TriStar 500 a range of about {{convert|5200|nmi|km}} with 246 passengers and baggage.

====Cabin====
The TriStar 500's maximum passenger capacity is 315, although no aircraft were operated with that number of seats.  A typical two-class layout might include 21 First Class and 229 Economy Class for a maximum of 250 passengers. More spacious three-class layouts used on longer routes include 233 with 12 First Class, 32 Business Class, and 189 Economy Class with Delta Air Lines.  The aircraft is equipped with six exits, two fewer than the long-body TriStars, thus reducing the exit limit maximum.