Profile Lockheed L1011 Tristar

Leading the field in this area came Boeing which introduced its Model 747 series. This aircraft, because of its spaciousness, led to the coining of the term ‘widebody’ to describe this new class of plane. Thus, American Airlines leased Boeing 747s from Pan American to open its transcontinental widebody service on March 2, 1970. Just over five months later the McDonnell Douglas design, the DC-10, also created to meet American’s requirement, flew for the first time on August 29, three months before its Lockheed rival, the L1011 Tristar. Both of these planes were very similar to each other with their wide bodies, wings swept at 35 degrees, two pod mounted turbofan engines under the wings and a third mounted on or in the rear fuselage.

Prior to this, the rivalry between McDonnell Douglas and Lockheed to obtain orders for their machines had been fierce. Both companies had vied for contracts with America’s ‘Big Four’ airlines, American, Eastern, TWA and Delta. Back in February 1968, American had placed an order for 25 DC-10 Series 10s in a contract worth $382m, however, McDonnell Douglas would not commit itself to production on the basis of this contract alone. At the same time, to counter the McDonnell Douglas success, Lockheed offered to slash a million dollars off each L1011 Tristar it sold. This manoeuvre resulted in sales orders for no less than 118 Tristars to Delta, Eastern and TWA plus 50 more to Air Holdings Ltd, a government backed British financial consortium. In spite of the loss of these potential customers, future production of the DC-10 was assured when an order for 60 was received from United Airlines in April, 1968.

The Tristar orders were particularly important for Lockheed because the company had not any significant success in the US commercial market since the years just following World War II. This had ended, except for servicing and support of existing aircraft, when production of the Electra had stopped in 1962. Lockheed’s market research leading up to the birth of the Tristar was indeed thorough. A foremost consideration was that the aircraft must be able to operate from existing airports without requiring special facilities. This was to be coupled with ease of maintenance, an automatic landing capability and high safety standards. Design work was equally thorough. For example, no less than eight full sized cabin mockups were built to determine the optimum cabin width affecting the layout, the number of seats in each row, number of aisles, etc, for passenger appeal and comfort and also to note how these variations affected the aircraft’s gross weight. A difference of 2’8″ (. 81m) between the minimum of 18’8″ (5. 69m) and the most desirable fuselage width would have added over 7,000Ib (3,175kg) to the empty weight but this allowed for two aisles and eight abreast seating. The final decision came down to a maximum cabin width of 18’11” (5. 77m) brought about by having a fuselage width of 19’7″ (5. 97m).

One of the most critical decisions, which almost had dire consequences for the Tristar, concerned the selection of its powerplant. Lockheed looked to the three main engine manufacturers, General Electric, Pratt and Whitney and RollsRoyce. The DC-1O designers had chosen as their options General Electric’s CF6 or either Pratt and Whitney’s JT9D engines while Lockheed’s first two customers, American Airlines and Delta, had advocated the Rolls-Royce RB211. This was a new three shaft turbofan derived from the RB207 which was lighter in weight and offered a better specific fuel consumption. At this time too, it offered a better economic proposition because of the relative values of the weak English pound and strong American dollar on the world market. The British company was pleased to receive the order in March, 1968, but it brought with it the seeds of disaster. In a final attempt to obtain the Lockheed contract, General Electric had offered an especially low price and this had obliged Rolls-Royce to drop its price per unit even further to a figure which would eventually prove to be well below realistic production costs.

First off the Line

On September 15, 1970, the first Lockheed Tristar L1011-1, Serial No. N1011, known as ‘Ship One’, came off the assembly line. It emerged as a cantilever low wing monoplane powered by three derated Rolls-Royce RB211-22F turbofan engines, each rated at 36,500Ib (16,556kg) thrust. The wings consisted of a centre section passing through the lower fuselage with an outer wing panel on each side and incorporated four integral fuel tanks. The fuselage was a semi monocoque structure of aluminium alloy with a constant cross-section diameter of 19’7″ (5. 97m), as already mentioned, for most of its length. Its landing gear was a retractable tricycle undercarriage with twin wheel units in tandem on each main gear and these retracted inwards to the fuselage wheel wells. The front nose

wheels were steerable 65 degrees to either side and retracted forward under the fuselage nose.

Crewed by H B Dees, R C Cokeley and G E Fisher, ‘Ship One’ made its first flight on November 16, 1970, and at this point the future looked rosy for Lockheed’s design, but trouble was just around the corner. Orders were being received, but even so, they had not yet reached breakeven sales figure which had been boosted to 250 because of the heavy price cutting and competition. However, serious problems were building up across the Atlantic.

On the Brink of Disaster

Towards the end of 1970, Rolls-Royce was in desperate financial trouble. Coupled with poor marketing policies, the development costs of the RB211 engine were skyrocketing. It was already six months behind supply schedule, particularly because of the problems associated with the advanced technology such as the incorporation of completely new carbonfibre material in its design. On February 4,. 1971, the company announced publicly that it was in financial difficulties, due primarily to the cost of developing the RB211 engine and that it had no alternative but to request the appointment of a Receiver. Rolls-Royce was bankrupt. The shock waves of the collapse quickly reached Lockheed which was obliged to halt production of the Tristar and layoff 9,000 of its workforce.

What was shocking news for Lockheed was nothing short of disastrous for the British Government. Clearly, because of its economic and strategic importance, England’s leading engine manufacturer could not be allowed to be lost. With government financing it was re-established as Rolls-Royce (1971) Ltd on February 23 and costs were indemnified to the Receiver. Then on May 11, the British Government signed an underwriting contract for the RB211 engine on the provision that the US Government guaranteed the future of the Tristar.

Meanwhile, besides its difficulties with Rolls-Royce, Lockheed was having financial problems of its own. These stemmed largely from huge losses it had suffered on its C-5A Galaxy military transport programme. President Nixon and Lockheed pressurized the American banks into providing $250m – which was agreed to provided that Congress also shared the burden. When, on July 30, the House of Representatives agreed to guarantee the loans, it was by a narrow margin of only three votes and just three days later the voting in the Senate was 49 ‘For’ to 48 ‘Against’. Lockheed and its Tristar had been allowed to survive only by the then narrowest of margins.

Initial delivery of the first L1011-1 Tristar was made to Eastern Airlines for crew training on April 6, 1972 and this was closely followed by a similar delivery to TWA. These aircraft were powered by Rolls-Royce RB211-22B engines each capable of 42,000lb (19,050kg) thrust giving them . a maximum cruising speed of 599mph (964kmh) at 30,000ft (9,145m) and an economical cruising speed of 553mph (890kmh) at 35,000ft (10,670m). They could carry a maximum payload – passengers and baggage, international reserves – of 83,300Ib (37,785kg) a distance of 3,086 miles (4,966km). Maximum weights for takeoff and landing were 430,000lb (195,048kg) and 358,000lb (162,386kg) respectively. FAA certification was granted on April 14 and the following day Eastern made its first passenger service flight. Revenue services began on April 26, from Miami and TWA began its first Tristar service on June 25. Towards the end of 1973, some 56 Tristars were in service with or were pending delivery to, Delta, Air Canada, British Airways: Court Line, All Nippon Airways and Lufttransport Unternehmen, as well as with Eastern and TWA.

Upon its entry into service, some teething troubles were experienced, mainly associated with its engines and these had to be frequently taken out of service for inspection. These problems were soon overcome and the aircraft proved reliable and adequate for US domestic air routes and for services across the Caribbean, but its short to medium range capabilities limited its potential for sale in the intercontinental market where, around this time, McDonnell Douglas was receiving orders for its DC-10 Series 30. There was clearly a need for a new model with an extended range and greater payload capacity.

The Quest for Longer Range

To meet this requirement, the Tristar L1011-100 was introduced. This aircraft’s external configuration was identical to the L1011-1 but it incorporated two new centre section fuselage tanks for 18,000lb (8,165kg) of additional fuel. It was certificated to operate at a maximum takeoff weight some 8% greater than that of the L1011-1 this now being 466,000lb (211,375kg) and the maximum loaded range was extended to 3,978 miles (6,403km). L1011-100’s were ordered by Air Canada, Cathay Pacific, Gulf Air, Saudi Arabian Airlines and TWA, but the improvements were not enough and only 14 were built.

Next came the Tristar L1011-200 powered by three RollsRoyce RB211-524 turbofans, each with 48,000lb (21,773kg)/ thrust, which was certificated by the FM on April 26, 1977. This machine offered improved takeoff and climb performances as well as extending the maximum loaded range to 4,145 miles (6,671km). Outwardly it was identical to the -1 and -100 models but even now the Tristar still could not match the range/payload capacity of the DC-10 Series 30. A more radical approach was required.

The real long-range version of the Tristar came with the L1011-500 model. This was powered by three 50,000lb (22,680kg) thrust RB211-524B or -52484 engines to lift off a maximum takeoff weight of 510,0001b (231,330kg). Through the introduction of an added centre section fuel tank with the capacity of 8,060 US gals (30,5101) the new machine carried a maximum fuel load of 212,000lb (96,160kg) which gave it a range with full payload of a much more useful 6,154 miles (9,905km). However, the fuselage was shortened by 13’6″ (4. 11m) and this, plus the space occupied by the added fuel tank, resulted in a payload decrease of one third in comparison with the L1011-200. Other changes included the relocation of the galley to the main deck, instead of having the previous lower deck food elevator arrangement of the earlier versions, plus the introduction of an RSB (Recovery Speed Brake) to guard against excessive accelerations by automatically deploying the speed brakes at 0. 85 Mach with applied ‘g’ and in 0. 885 Mach conditions in level flight.

The -500 can be recognised from the other models by its shorter fuselage and the introduction of a streamlined fairing for the junction of the fuselage and the rear engine intake, which reduced drage by 35. In a typical mixed class configuration with 24 first class passengers in nine abreast seating it could carry 246 passengers. Absolute maximum passenger capacity was put at 330. L1011-500s entered service with British Airways on May 7, 1979.

Although ‘Ship One’ had not been a prototype in the true sense, it served as such and was duly used by Lockheed for flight testing new avionics. As configured in mid 1980, it was identified as the ‘Advanced Tristar’ and was powered by three RB211-524s. It was for instance, used to examine a mod which extended the wing tips by 4’6″ (1. 37m). To reduce drag and to overcome the necessity of strengthening the wing structure, new automatically controlled ailerons were incorporated. Early flight testing of these features showed fuel savings were achieved in the vicinity of 3% ‘Ship One’ was also used to test automatic thrust control in order to provide a reserve of power in case of engine failure during takeoff, automatic brakes to ensure optimum efficiency under all runway conditions as well as new advanced flight control systems.

Extended wingtips and automatically controlled ailerons were introduced on Pan American -500s in 1980 and became standard the following year. In early 1981, Lockheed initiated a modification programme to retrofit the wingtip extensions on all previously built -500s.

An L1011-500, equipped with a Collins FCS-240 digital flight control system, became the first aircraft to have FAA certification for operating in Category IIIA conditions using a fully digital autopilot system on June 17, 1981. Production Tristars fitted with this system were first delivered to PanAm and Air Canada in mid 1981 and later became standard.

The End and New Beginnings

Although production and development of the Tristar continued throughout the 1970s and the beginning of the 1980s, because of economic recession, sales of the aircraft had constantly failed to live up to market projections, so a decision was taken by Lockheed late in 1981 to finally wind down and thus to end the project. The company is believed to have lost in the vicinity of $10m on each aircraft delivered, totalling up to a massive $2. 5bn. Of the 249 orders received, 161 were for L1011-1s, 14 were for L1011-100s, 24 were L1011-200s and 50 were for long-range L1011-500s. In addition to this, eleven L1011-100s were created by upgrading -1s as also were six L1011-200s. ‘Ship One’, which was used as the developmental aircraft, was retained by the company so that, in all, there were 250 built. Production ceased following the delivery of the last two aircraft to Alia in June, 1985, leaving Lockheed without a commercial jet transport programme.

However, this did not mark the end of the Tristar story. In the middle of 1986 a new member of this family of aircraft began to emerge. This was the L1011-250 created from the basic L1011-1 and powered by new improved Rolls-Royce RB211-524B turbofans. It featured additional fuel storage capacity permitting the carrying of 213,640Ib (96,992kg) of fuel instead of the early aircraft’s 159,560lb (72,440kg) without decreasing the payload potential, Along with this, there was a series of modifications to increase the strength of the wings, landing gear and fuselage. This new machine was now in the same range class as the intercontinental L1011-500 version which, because of its shortened fuselage, had lost some of its stability around horizontal (pitch) axis at high Mach numbers and could only carry 246 passengers.

Rolls-Royce and Lockheed discussed the advantages of the modifications with the 21 operators of the 146 Tristars which were able to be converted, those with the manufacturer’s serial numbers 1052 or higher. The first company to take advantage was Delta airlines with six of its L1011-1 s for conversion. By Delta’s own reckoning the -250 could carry 39 more passengers and a maximum payload nearly 5,000Ib (227kg) greater than the -500 and its range with a full passenger load was 5,300 miles (8,530km) compared with that of the -1s it had in service of 3,200 miles (5, 150km). The modifications were not carried out by the parent company but by Delta itself and, while there may be 12-18 months lead time wait for the kits from Rolls-Royce and Lockheed, the actual process of conversion was found to take from 5-8 weeks per aircraft at a cost of $24m each.

Meanwhile, Tristars had joined the Royal Air Force. As a direct result of the 1982 Falklands war and the demands made on the RAF’s aerial tanker fleet, the service looked around for wide bodied tanker/transport aircraft to replace its ageing Handley Page Victors and supplement its VC10s. It had to choose between buying and modifying civil airliners such as the DC-10, Tristar or perhaps the Airbus and ordering new the McDonnell Douglas KC-10 Extender, which was much more expensive but already in production for the USAF. Eventually, six British Airways Tristar L1011-500s which were no longer required by the airline, were purchased and the deal initially included the use of British Airways’ flight crews and Tristar simulators to train RAF aircrew.

In . mid 1983, two Tristars, ZD950 and ZD953, began to undergo conversion into military tankers, the work being carried out by Marshall of Cambridge. The first Tristar K1 tanker (ZD950) made its initial flight on July 9, 1985. Modifications included a refuelling probe mounted above the flightdeck, additional tanks in the underfloor cargo holds to permit an extra 100,000lb (45,400kg) fuel capacity and twin hose drum units in the rear fuselage. No. 216 Squadron was reformed at Brize Norton to fly the Tristars, the numbers of which were boosted by the purchase of three more surplus aircraft from Pan American. The unit will eventually operate three versions of the machine: the K1 tanker/ transport; the KC1 fitted with a forward freight door and cargo handling system; and the K2 transport, which are former PanAm aircraft. The first flight of one of these planes by an all RAF crew occurred on March 1, 1985.

Though it was a commercial failure, the Lockheed Tristar has always won fond acclaim by its airline operators and pilots alike. While it will largely be replaced by the new generation twinjets in the decade ahead, the Tristar will still . soldier on in the role as tanker for many more years in RAF service