Lockheed L-1011 TriStar

Lockheed L-1011 TriStar

The Lockheed L-1011 TriStar is a three-engined widebody airliner seating up to 400 passengers. It was the third widebody airliner to enter service and it competed head-on with the McDonnell Douglas DC-10. The TriStar became the last airliner produced by Lockheed. The aircraft type is not in use with airlines any more.

During the 1960s, Lockheed, builder of the famous piston-engined Constellation, was eagerly looking for an opportunity for a comeback on the market for commercial airliners. The US aircraft manufacturer had missed the first decade of jet age. It was without a competitor to the Boeing 707 and Douglas DC-8 and in the late 1950s, it developed the L-188 Electra turboprop instead of a jetliner and since production of this ill-fated airliner ended in 1961, Lockheed didn't produce any airliners apart from a small number of 'civilised' Hercules military transport planes. The loss of the American contest for a supersonic transport (SST) also meant a major blow. An American Airlines specification in the mid-sixties for a 'Jumbo Twin', a widebody airliner smaller than the Boeing 747, seemed to offer new chances. The idea was an aircraft with about the same performance as the Boeing 727, but with twice the number of passengers.

Competing with the DC-10

After discussions with potential customers, the Jumbo Twin became a Jumbo Trijet. The twin-engine designs were restricted to an intermediate stop on US east-coast to west-coast flights, but many airlines preferred transcontinental range. The time for big twins simply had not come yet. In these days, big twins would simply not be good enough yet. Trijets had many advantages over twins. Trijets were more flexible. They offered better performance. They climbed better and needed less runway so that they could operate from smaller airports. Trijets also faced less restrictions for flights over water and in low-visibility weather. And after an engine-failure, trijets could be ferried to their homebase on two engines, but twins weren't allowed to do that on one engine.

Lockheed designed an aircraft that became in many ways identical with the competing McDonnell Douglas DC-10. Both aircraft were fitted with three high-bypass turbofan engines, seated around 300 passengers, had about the same fuselage cross section diameter and even had exactly the same wingspan. The main visual difference was the location of the tail engine. On the TriStar's it was placed at the end of the fuselage and fed with air by an S-like duct in the fin's base. The DC-10's middle engine was located higher, above the rear fuselage in a straight duct. Another difference was that Lockheed selected only one engine type, the Rolls-Royce RB.211, while McDonnell Douglas offered its DC-10 customers a choice between General Electric and Pratt & Whitney turbofan engines.

In late 1967, Lockheed and McDonnell Douglas became involved in a fierce battle to win customers for their proposed, but not yet launched trijet projects. Douglas initially won the first round with an American Airlines contract for 25 DC-10s on February 19, 1968, but this was not yet enough for full-scale development and production. The second round was won by Lockheed. On March 29, 1968, it announced a total of 144 orders and options, from Eastern Airlines (33 orders plus 11 options), TWA Trans World Airlines (25 plus 25) and Air Holdings Company, a British firm established to sell or lease TriStars to non-US airlines (30 plus 20). That day, Lockheed announced the full go-ahead of the TriStar programme. McDonnell Douglas officially launched the DC-10 almost a month later, on April 26, 1968, after United Airlines chose the DC-10 and ordered 30 and took options on 30 more.

Financial trouble

The Lockheed L-1011 TriStar flew for the first time on November 16, 1970, from Palmdale in California. The TriStar was considered to be technically more advanced than the DC-10, but Lockheed suffered delays because of financial problems. The manufacturer was already weakened by the C-5A Galaxy programme, a project based on a fixed price contract, so that Lockheed had to pay serious cost overruns from its own financial resources.

Another financial setback was the cancellation of the military Cheyenne helicopter by the US Army. In the meantime, Rolls-Royce faced difficulties with the development of the RB.211 turbofan. During tests the innovative carbon fibre blades of the front fan of the engine appeared not to be bird-proof and showed corrosion, leading to breaking-off blades. The blades were substituted by more traditional titanium ones, but these added weight to the engine.

Furthermore, Rolls-Royce had underestimated the necessary development time for the new engine and priced the engine below its real cost-level. In February 1971, these circumstances led to the financial collapse of the British engine manufacturer. To save the company, the British government took control over Rolls-Royce. But it wanted to continue the RB.211 development only if Lockheed was prepared to pay a higher price for the engines. Lockheed had no choice, because it would face much longer delays and high modification costs to replace the RB.211 by another engine.

Government support

The series of setbacks forced Lockheed to lay off 6,500 workers, but it remained short of money. In the summer of 1971, it gained support from the US government, which didn't want to lose a company with so much knowledge and experience in building military aircraft as Lockheed had. In August 1971, president Richard Nixon signed guarantees for loans up to 250 million dollar. Additionally, in September, Lockheed signed contracts with banks, Rolls-Royce and the launch airlines for a 650 million dollar financing package. Lockheed and the TriStar were saved now, but the problems had not contributed to faith in the aircraft with the airlines. One of the big early TriStar customers, Delta Air Lines, even ordered a number of McDonnell Douglas DC-10s to be sure of having widebodies in its fleet at the beginning of the widebody era.

First delivery

The first 'Ten-Eleven' was delivered to Eastern Airlines and introduced on the airline's Miami-Atlanta-New York service on 26 April 1972, eight months behind the first delivery of the DC-10. The TriStar sold only slowly during the rest of the 1970s. To stimulate sales, Lockheed bribed Japanese politicians. In order to influence All Nippon Airlines (ANA) to purchase the TriStar, Lockheed paid approximately 1.8 million dollar to the Japanese prime minister's office. The scandal, which came to light in 1976, forced the then-prime minister of Japan, Kakuei Tanaka, to resign. Judicial processes carried on for a decade.

Lockheed L-1011-1, -100, -200

Lockheed developed several versions of the TriStar. The TriStar-1, -100 and -200 all had the same fuselage length but were different in range and engine-variants. Conversions based on these versions resulted in three new variants: TriStar-50, -150 and -250. These three variants were never built new.

Lockheed L-1011-500

The L-1011-500 was a short-fuselage, long-range version of the TriStar, with increased wing span. Lockheed aimed the L-1011-500 to airlines wanting to replace Boeing 707 and Douglas DC-8 aircraft and airlines for which the DC-10, 747 and standard TriStars were too big or lacked range. The L-1011-500's fuselage was 4.30 m (14 ft) shorter than that of the earlier versions and the maximum takeoff weight was increased. It seated less passengers but carried more fuel to offer more range.

New on the TriStar was a Flight Management System to help minimise fuel burn during cruise flight, including a cathode ray tube named 'CDU' (cockpit display unit). Aerodynamic refinements included a reshaped wing-fuselage fillet and a fairing under the inlet of the centre engine to improve the airflow in order to reduce drag and decrease noise in the aft cabin. Cabin and freight doors were re-arranged. Two small passenger doors at the rear of the cabin were deleted. Lockheed offered a variant with a bagage hold and just 190-200 seats on the main-deck, and the belly for just cargo.

The TriStar 500 was flown for the first time on 16 October, 1978, and the FAA type certification was issued six months later. British Airways took delivery of its first aircraft on 29 April, 1979. The airline performed its first commercial flight with the type on May 7, 1979, from London to Abu Dhabi. Lockheed built a total of 50 aircraft of this version, far less that it expected when it launched the L-1011-500. Some ex-BA and ex-Pan Am aircraft were later converted to military aerial tankers and entered service with the British Royal Air Force.

Proposed developments

Lockheed considered many TriStar versions that were never built. An early proposed stretched version was the L-1011-8. The fuselage was 1,02 m (3 ft 4 in) longer than the standard TriStar and a 4,47 m (14 ft 8 in) wider wingspan. The wing area was increased with 20 per cent, it had more powerful RB.211 engines and higher weights. The main undercarriage bogies had six wheels instead of four. Lockheed hoped to win an order from the KSSU airline group (KLM, SAS, Swissair, UTA), but they selected the DC-10-30 instead.

A later, more stretched version was the L-1011-300 with a 30 ft (9 m) longer fuselage, to a total length of 63.2 m (207 ft 4 in), seating 410 passengers. This version was proposed to All Nippon Airways (ANA), which was in need of a high-capacity airliner for domestic use. After ANA chose the Boeing 747SR (Short Range), Lockheed stopped the development. The L-1011-400 was a proposed short-range version for 220-250 passengers and lower weights. It combined the fuselage of the L-1011-500 with the smaller wing of the L-1011-1 and should have been powered by derated Rolls-Royce RB.211-22B engines. The L-1011-400A was designed with a 2,03 m (80 inch) shorter fuselage for 200-231 passengers and extensions of both wingtips. A combination of the L-1011-200 fuselage and the L-1011-500 wing would have resulted in a 'L-1011-500 Stretch'.

The L-1011-600 'BiStar' was a proposal for a twin-engined variant, with a fuselage almost 6 m shorter than that of the TriStar 500 (44,22 m), seating 178 passengers eight-abreast and 200 nine-abreast. Its inner wing was new, but it used basic TriStar outer wing panels. Its range would have been 3,700-4,990 km. (Image: Lockheed). A more drastic proposal was the L-1011-600A, with a completely new, supercritical wing, a more optimised rear fuselage design and composite materials in the structure. Its length would have been only 42,98 m. Lockheed also studied a Combi-variant of the standard L-1011, with a large freight door aft of the wing.

Lockheed built 250 TriStars and delivered the final production aircraft in 1984. The closure of the assembly line marked the end of Lockheed as a builder of passenger airliners. From the year 2000, the TriStar gradually disappeared from the aviation scene. A small number was converted to freighter, but as a cargo plane, the type appeared far less popular than the DC-10.

Stargazer

The only Lockheed TriStar still flying today, is an aircraft named 'Stargazer'. It is operated by the U.S. aircraft manufacturer Northrop Grumman on behalf of its subsidiary Orbital ATK, which produces satellites and rockets. The aircraft was delivered to Air Canada in 1974 and after its airline career, it was modified in 1993-1994 to enable it to launch Pegasus rockets high in the air. The Pegasus brings satellites into low Earth orbit. The name 'Stargazer' is a homage to Star Trek: before Jean-Luc Picard became captain of the Enterprise, he was commander of a spaceship named 'Stargazer'. The aircraft will continue flying until launch contracts dry up or component availability becomes a problem.

The Stargazer with a Pegasus rocket under its belly. (Photo: NASA)

Lockheed L-1011-200 Specifications

Wingspan: 47.35 m (155 ft 4 in). Length: 54.17 m (177 ft 8 in). Height: 16.87 m (55 ft 4 in).
Empty weight: 113,000 kg (248,400 lb). Max. take-off weight: 211,374 kg (466,000 lb).
Accommodation: 256-400 passengers. Range: 6,667 km (3,600 nm). Cruise speed: 954 km/h (515 kts).
Engines: three Rolls-Royce RB.211-524B (222 kN / 50,000 lb).

---

Lockheed L-1011-500 Specifications

Wingspan: 50,09 m (164 ft 4 in). Length: 50,05 m (164 ft 2 in). Height: 16.87 m (55 ft 4 in).
Empty weight: 111,000 kg (245,400 lb). Max. take-off weight: 231,332 kg (510,000 lb).
Accommodation: 246-330 passengers. Range: 9,900 km (5,345 nm). Cruise speed: 972 km/h (525 kts).
Engines: three Rolls-Royce RB.211-524B (222 kN / 50,000 lb).