Editing Lockheed L-1011 TriStar (section)

==Development==

===Origins===
In the 1960s, [[American Airlines]] approached Lockheed and competitor Douglas (later McDonnell Douglas) with the need for an airliner that could carry 250 passengers on transcontinental routes.<ref name="auto">{{Cite web |url=http://www.lockheedmartin.com/us/100years/stories/l-1011.html |title=L-1011: Luxury Among the Clouds|date=March 27, 2018}}</ref> Lockheed had not produced civilian airliners since 1961 with the [[Lockheed L-188 Electra|L-188 Electra]]. In the 1950s the Electra was designed for turboprop propulsion, which Lockheed successfully used on the [[Lockheed C-130 Hercules|C-130 Hercules]] military transport. Even after the Electra overcame vibration problems that caused several crashes early in its career, the market for large airliners would soon shift over to jet airliners such as the [[Boeing 707]] and [[Douglas DC-8]].<ref>{{cite web |url= http://www.airdisaster.com/cgi-bin/view_details.cgi?date=09291959®=N9705C&airline=Braniff+Airlines |archive-url= https://archive.today/20120527061637/http://www.airdisaster.com/cgi-bin/view_details.cgi?date=09291959%C2%AE=N9705C&airline=Braniff+Airlines |archive-date= May 27, 2012 |title= Accident Synopsis 09291959 |work= AirDisaster.com |year= 2008 |url-status= usurped |access-date= July 16, 2011}}</ref><ref>{{cite web |url= http://www.hq.nasa.gov/office/pao/History/SP-440/ch6-5.htm |title= NASA Wind Tunnel Tests |publisher= National Aeronautics and Space Administration |access-date= July 16, 2011 |archive-date= October 30, 2011 |archive-url= https://web.archive.org/web/20111030224810/http://www.hq.nasa.gov/office/pao/History/SP-440/ch6-5.htm |url-status= dead }}</ref><ref>{{cite magazine |url= http://www.time.com/time/magazine/article/0,9171,895003,00.html |archive-url= https://web.archive.org/web/20090925184233/http://www.time.com/time/magazine/article/0,9171,895003,00.html |url-status= dead |archive-date= September 25, 2009 |title= Disasters: Electra's Tragedy |magazine= Time |date= October 17, 1960}}</ref> Lockheed won contracts for jet military transports with the [[C-141 StarLifter]], and pioneered very large jet transports with the large [[C-5 Galaxy]] with its high-bypass turbofan engines. Boeing lost the military contract, but its private-venture 747 would later capture a much larger civilian airliner market for [[wide-body aircraft|wide-body]] airliners.

Having experienced difficulties with some of its military programs, Lockheed was eager to re-enter the civilian market with a smaller wide-body jet, and its response was the L-1011 TriStar. Douglas Aircraft answered American Airlines with the [[McDonnell Douglas DC-10|DC-10]], which had a similar three-engine configuration and dimensions.<ref name="Lockheed L-1011.">{{cite news |url= https://www.pbs.org/kcet/chasingthesun/planes/l1011.html |title= Lockheed L-1011 |work= Chasing the Sun |publisher= PBS |access-date= July 16, 2011}}</ref> Despite their similarities, the L-1011 and DC-10's engineering approach differed greatly. McDonnell, who had recently taken over Douglas Aircraft, directed DC-10 development on a "very firm budget, and cost overruns were unacceptable{{Snd}} even at the expense of safety", and the conservative approach meant reusing [[Douglas DC-8]] technology. By contrast, Lockheed would "take the most advanced technology of the day and when that technology was lacking, Lockheed created it" for the L-1011<ref name="ReferenceA">{{Cite web |url=http://www.airlinereporter.com/2015/09/requiem-trijet-masterpiece-lockheed-l-1011-tristar/ |title= Requiem for a Trijet Masterpiece - the Lockheed L-1011|date= September 30, 2015}}</ref> to give it lower noise emissions, improved reliability, and higher efficiency over first-generation jet airliners. The TriStar name was selected in a Lockheed employee naming contest for the airliner.{{citation needed|date=August 2017}} The advanced technology that went into the TriStar resulted in a high purchase price.{{cn|date=June 2022}}

[[File:Lockheed L-1011-1 Tristar, Trans World Airlines (TWA) JP6786696.jpg|thumb|[[TWA]] Lockheed L-1011-1 Tristar twin-aisle cabin in 1972]]
The TriStar's design featured a twin-aisle interior with a maximum of 400 passengers and a three-engine layout. The TriStar was originally conceived as a "jumbo [[twinjet|twin]]", but a three-engine design was ultimately chosen to give the aircraft enough thrust to take off from existing runways.<ref name="Lockheed L-1011."/> Also, before the establishment of [[ETOPS|Extended Operations]] standards by the [[Federal Aviation Administration|FAA]] in the 1980s, commercial jets with only two engines were not allowed to fly more than 30 minutes away from an airport, making trans-oceanic flights impossible. The main visible difference between the TriStar and its similar trijet competitor, the McDonnell Douglas DC-10, is the central tail engine configuration: the DC-10's engine is mounted above the fuselage for simplicity of design and more economical construction, while the TriStar's engine is mounted to the rear fuselage and fed through an [[S-duct]] (similar to the [[Boeing 727]]) for reduced drag and improved stability.<ref name="airlinereporter.com">{{Cite web |url=http://www.airlinereporter.com/2014/03/lockheed-l1011-saying-goodbye-another-trijet/ |title= The Lockheed L1011 - Saying Goodbye to Another Trijet|date= March 24, 2014}}</ref><ref>{{cite book |url= https://books.google.com/books?id=bEdWAAAAMAAJ&q=s-duct |title= The Aeronautical Journal |volume= 78 |publisher= Royal Aeronautical Society |year= 1974 |pages= 392, 398 |access-date= July 16, 2011}}</ref> Lockheed engineers were able to maintain straight-through engine performance 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 the design of the L-1011 indicated that losses of using an S-duct were more than compensated for by the above savings.<ref name="saeJournal">{{cite book |url= https://books.google.com/books?id=0GVTAAAAMAAJ&q=s-duct+ |title= SAE Transactions |publisher= Society of Automotive Engineers |date= 1970 |page= 1436 |access-date=December 11, 2008}}</ref> A further major difference between the L-1011 and the DC-10 was Lockheed's selection of the [[Rolls-Royce RB211]] as the only engine for the L-1011.<ref>{{cite web |url= http://www.rolls-royce.com/civil_aerospace/technology/threeshaft.jsp |title= Three Shaft Engine Design |publisher= Rolls-Royce |archive-url= https://web.archive.org/web/20061016141514/http://www.rolls-royce.com/civil_aerospace/technology/threeshaft.jsp |access-date= July 16, 2011 |archive-date= October 16, 2006}}</ref><ref name="The_Magic_Of_A_Name">{{cite book |last= Pugh |first= Peter |title= The Magic of a Name: The Rolls-Royce Story, Part Two: The Power Behind the Jets |location= London |publisher= Icon Books |year= 2001 |isbn= 1-84046-284-1 |pages= 120–122}}</ref> As originally designed, the RB211 [[turbofan]] was an advanced three-spool design with a [[carbon fiber]] fan,<ref>{{cite web |url= http://www.flightglobal.com/pdfarchive/view/1968/1968%20-%202418.html |title= The New Steel |work= Flight International |date= October 24, 1968}}</ref> which would have better efficiency and [[power-to-weight ratio]] than any competing engine like the [[General Electric CF6]] that powered the DC-10. In theory, the triple spool would produce the same or more power as existing double spool engines while having a smaller cross section that would reduce drag.<ref name="ReferenceA"/><ref name="airlinereporter.com"/>

[[File:Delta Air Lines L-1011 N713DA.jpg|thumb|The S-duct configuration with the air intake offset from the rear engine]]
American Airlines opted for the Douglas DC-10, although it showed considerable interest in the L-1011. American intended to convince Douglas to lower its price for the DC-10, which it did.<ref>{{cite book |author-link= Walter J. Boyne |last= Boyne |first= Walter J. |title= Beyond the Horizons: The Lockheed Story |location= New York |publisher= St. Martin's Press |year= 1998 |isbn= 978-0-312-19237-2 |page= 354}}</ref> Without the support of American, the TriStar was launched on orders from [[Trans World Airlines|TWA]] and Eastern Air Lines.{{citation needed|date = October 2023}}

[[File:Lockheed L-1011-1 Tristar, Lockheed JP5893645.jpg|thumb|Prototype L-1011 TriStar being prepared for its first flight test in 1970]]
Although the TriStar's design schedule closely followed that of its competitor, McDonnell Douglas beat Lockheed to market by a year due to delays in powerplant development. In February 1971, after massive development costs associated with the RB211, Rolls-Royce went into [[Administrative receivership|receivership]].<ref>{{cite magazine |url= http://www.time.com/time/magazine/article/0,9171,904742,00.htm |archive-url= https://web.archive.org/web/20121107125907/http://www.time.com/time/magazine/article/0,9171,904742,00.htm |url-status= dead |archive-date= November 7, 2012 |title= Lockheed's Rough Ride with Rolls-Royce |magazine= Time |date= February 15, 1971}}</ref><ref>{{cite news |last= Wood |first= Robert |url= https://pqasb.pqarchiver.com/latimes/access/661257082.html?dids=661257082:661257082&FMT=ABS&FMTS=ABS:AI&type=historic&date=Nov+12%2C+1970&author=&pub=Los+Angeles+Times&desc=Jumbo+Jet+Engines+for+Lockheed+Push+Rolls-Royce+in+Red&pqatl=google |title= Jumbo Jet engines for Lockheed push Rolls-Royce in red |work= Los Angeles Times |date= November 12, 1970 |access-date= July 6, 2017 |archive-date= November 5, 2012 |archive-url= https://web.archive.org/web/20121105083855/http://pqasb.pqarchiver.com/latimes/access/661257082.html?dids=661257082:661257082&FMT=ABS&FMTS=ABS:AI&type=historic&date=Nov+12,+1970&author=&pub=Los+Angeles+Times&desc=Jumbo+Jet+Engines+for+Lockheed+Push+Rolls-Royce+in+Red&pqatl=google |url-status= dead }}</ref> This halted L-1011 final assembly and Lockheed investigated the possibility of a US engine supplier.<ref>{{cite news |last= Lindsey |first= Robert |url= https://www.nytimes.com/1971/02/05/archives/lockheed-seeks-us-engine-now-retooling-cost-of-a-switch-could-run.html |title= Lockheed Seeks U.S. Engine Now: Retooling Cost of a Switch Could Run to $100-million |work= The New York Times |date= February 5, 1971}}</ref> However the engineering was finalized at that stage in the TriStar's development and its S-duct, which was designed to fit the smaller cross-section of the triple spool RB-211 engine that would have reduced drag, was too small in diameter to accommodate an existing double spool engine.<ref name="airlinereporter.com"/> One option presented was potential outsource of RB-211 production to Canadian manufacturer [[Orenda Engines]].<ref>{{cite news |url= https://news.google.com/newspapers?id=tK4tAAAAIBAJ&pg=2030,1953777&dq=l-1011+international&hl=en |title= Canadian 'key' has no plans |work= Montreal Gazette |date= February 9, 1971}}</ref>

The British government agreed to approve a large state subsidy to restart Rolls-Royce operations on condition that the U.S. government guarantee the bank loans Lockheed needed to complete the L-1011 project.{{refn|The British government did approve a large state subsidy because if Lockheed (which was weakened by the difficulties) had failed, the market for the RB211 would have evaporated.<ref>{{cite news |last= Lewis |first= Antony |url= https://www.nytimes.com/1970/11/12/archives/british-grant-set-for-rollsroyce-government-to-spend-up-to.html |title= British Grant Set for Rolls-Royce: Government to Spend up to $100-Million in Rescue Bid |work= The New York Times |date= November 12, 1970}}</ref>|group=Note}} Despite some opposition, not least from the then [[List of Governors of California|Governor of California]], [[Ronald Reagan]], the U.S. government provided these guarantees.<ref name="loan_guarantee">{{cite magazine |url= http://www.time.com/time/magazine/article/0,9171,944387,00.html |archive-url= https://web.archive.org/web/20070930044753/http://www.time.com/time/magazine/article/0,9171,944387,00.html |url-status= dead |archive-date= September 30, 2007 |title= New Life for TriStar |magazine= Time |date= May 17, 1971 |access-date= July 16, 2011}}</ref> For the rest of the RB211 project, Rolls-Royce remained a government-owned company.<ref>{{cite news |url= https://news.google.com/newspapers?id=HpkuAAAAIBAJ&pg=5363,2738212&dq=rolls-royce+lockheed&hl=en |title= Rolls-Royce Still Alive and Kicking |work= Montreal Gazette |date= February 18, 1972}}</ref>

===Production===
[[File:Pacific Southwest Airlines L-1011 N1079.jpg|thumb|left|An L-1011-1 of [[Pacific Southwest Airlines]] at Lockheed's Palmdale plant]]

The TriStar's [[List of Lockheed aircraft|internal Lockheed model number]] is L-093. The TriStar was manufactured in Lockheed facilities in Burbank and [[Palmdale, California]].

The prototype L1011 first flew on November 16, 1970.<ref name=David_Encyclo>{{cite book |editor-last= Donald |editor-first= David |chapter= Lockheed L-1011 TriStar |title= The Complete Encyclopedia of World Aircraft |location= New York |publisher= Barnes & Noble Books |year= 1997 |isbn= 0-7607-0592-5 |page= 579}}</ref> The L-1011 was certified on April 14, 1972, with the first airliner delivered to Eastern Air Lines on April 26, 1972.<ref name=David_Encyclo/> In 1972, its unit cost was US$20 million (~${{Format price|{{Inflation|index=US-GDP|value=20000000|start_year=1972}}}} in {{Inflation/year|US-GDP}}).<ref name=Flight10aug1972>{{cite magazine |url= https://www.flightglobal.com/pdfarchive/view/1972/1972%20-%202020.html |title= Airliner price index |magazine= Flight International |date= August 10, 1972 |page= 183}}</ref> To further publicize the new aircraft, an L-1011, possibly the prototype, was taken on a world tour during 1972 by famed Lockheed test pilot [[Tony LeVier]]. In a demonstration by test pilots LeVier and Charles Hall, 115 crew members, employees, and reporters embarked on the TriStar for a 4-hour, 13-minute flight from Palmdale to Dulles Airport "with the TriStar's AFCS [Automatic Flight Control System] feature engaged from takeoff roll to landing", and Lockheed touted it as "a groundbreaking moment: the first cross-country flight without the need for human hands on the controls".<ref name="auto"/>

Lockheed discovered fairly early on that the TriStar suffered from higher than estimated structural weight, engine weight, and specific fuel consumption. To rectify this problem and to meet performance guarantees, Lockheed developed a structural kit that allowed [[maximum takeoff weight]] (MTOW) to be increased on production aircraft from {{convert|409000|to|430000|lb|kg}}. However, the weight problems affected the weight and desirability of early production L-1011-1 aircraft, known as Group 1 (serial numbers 1002 through to 1012).{{cn|date=January 2023}}

Group 1 aircraft have an Operating empty weight ([[OEW]]) of {{convert|252700|lb|kg}}, about {{convert|12700|lb|kg}} higher than later aircraft, while Group 2 aircraft (serial numbers 1013 through 1051) have an OEW of {{convert|247000|lb|kg}}, some {{convert|4700|lb|kg}} lower. These aircraft, in general, also have different center of gravity envelopes with the forward center of gravity limit on the early aircraft being more restrictive at higher gross weights. Groups 1 and 2 aircraft (serial numbers 1002 to 1051) are upgradeable only to -50 or -150 specifications, although the Group 1 aircraft (up to serial number 1012) still maintain their operating disadvantages. All L-1011-1 aircraft from serial number 1052 onwards are Group 3 aircraft and are fully upgradeable to all variants up to -250 specification.

[[File:British Airways Lockheed L-1011-385-1 TriStar 1 Gilliand.jpg|thumb|[[British Airways]] L-1011 TriStar in Landor livery in 1986]]
Costs at Rolls-Royce were controlled and its efforts largely went into the original TriStar engines, which needed considerable modifications between the L-1011's first flight and service entry. The competition, notably General Electric, was very quick to develop its [[General Electric CF6|CF6]] engine with more thrust, which meant that a heavier "intercontinental" DC-10-30 could be more quickly brought to market. The flexibility afforded to potential customers by a long-range DC-10 put the L-1011 at a serious disadvantage. Rolls-Royce went on to develop the high-thrust [[Rolls-Royce RB211#RB211-524 series|RB211-524]] for the L-1011-200 and -500, but this took many years.<ref>{{cite book |chapter-url= http://www.emeraldinsight.com/Insight/viewContentItem.do?contentType=Article&hdAction=lnkpdf&contentId=1682587 |chapter= Engine Update |title= Aircraft Engineering and Aerospace Technology |volume= 48 |year= 1976 |page= 5}}</ref>

The resultant delay in Lockheed and Rolls-Royce offering a high gross variant with a longer range, coupled with the TriStar's delayed introduction, meant that only 250 TriStars were sold compared to over 400 DC-10s.<ref name="airlinereporter.com"/> Lockheed needed to sell 500 airliners to break even, but in 1981, the company announced production would end with the delivery of the 250th and last L-1011 on order in 1984.<ref>{{cite news |last= Jones |first= Jack |url= https://pqasb.pqarchiver.com/latimes/access/655488642.html?dids=655488642:655488642&FMT=ABS&FMTS=ABS:AI&type=historic&date=Dec+08%2C+1981&author=&pub=Los+Angeles+Times&desc=Saddened+Lockheed+Workers+Still+View+L-1011+With+Pride&pqatl=google |title= Saddened Lockheed workers still view L-1011 with pride |work= 'Los Angeles Times |date= December 8, 1981 |access-date= July 6, 2017 |archive-date= November 5, 2012 |archive-url= https://web.archive.org/web/20121105084013/http://pqasb.pqarchiver.com/latimes/access/655488642.html?dids=655488642:655488642&FMT=ABS&FMTS=ABS:AI&type=historic&date=Dec+08,+1981&author=&pub=Los+Angeles+Times&desc=Saddened+Lockheed+Workers+Still+View+L-1011+With+Pride&pqatl=google |url-status= dead }}</ref><ref>{{cite news |url= https://news.google.com/newspapers?id=x6MiAAAAIBAJ&pg=3972,7629695&dq=lockheed+l-1011&hl=en |title= Lockheed to stop l-1011 production |work= Sumter Daily Item |date =December 8, 1981}}</ref>

The TriStar's failure to achieve profitability caused Lockheed to withdraw from the civilian aircraft business.<ref name="withdraw_from_civil_aviation"/> The TriStar's rivalry with the DC-10 has been seen as a "case study in what can happen when two manufacturers attempt to split a market that simply could not support both aircraft". Lockheed lacked the resources to follow up with several proposals based on the TriStar wing and airframe, including a wide-body twinjet and a stretched quad-jet (one of the quadjet proposals consisting of two underwing engines and two rear fuselage-mounted engines). McDonnell Douglas was also financially weakened and could only develop the [[McDonnell Douglas MD-11|MD-11]], a refinement of the DC-10, instead of an all-new design to challenge the next generation of twinjets like the [[Boeing 777]].<ref name="ReferenceA"/>

Ultimately, both the L-1011 and the DC-10/MD-11 were doomed by this next generation of widebody twinjets such as the Boeing 777 and the [[Airbus A330]] - as the rules on [[ETOPS]] gradually extended to longer distance routes - thanks largely to the improving reliability and performance of jet engines which made trijet aircraft less cost efficient to operate; widebody twinjets become the dominant configuration for long haul operations.