Tristar Reborn

Boeing survived due to the unique appeal of the 747 and the continuing back-up success of the 727 and 737 models. McDonnell Douglas also had the popular DC-9 in addition to a strong start-up order backlog for the new DC-10. Lockheed on the other hand had only the Tristar in its commercial division and when orders slowed, the repercussions not only dragged down Lockheed but virtually bankrupted Rolls-Royce, who had counted on a flood of orders for their new RB. 211s.

History tells us that both Lockheed and Rolls survived, albeit a little leaner and more subdued than before. However, it was not until the end of the seventies, a decade that commenced with a virtual death threat over the heads of the two companies, that the primary sources of their economic passing were transformed into money-making programs that are now great assets to both companies.

The sole ingredient lacking in the Tristar range up till the late seventies was simply range. The initial L. 1011s were short to medium-range transports which clearly steered many operators, too small for the Boeing 747, straight into the DC-10 camp which had on offer several versions ably fitting the short, medium and long-range requirements.

There had been a significant change in the level of activity of the Tristar program in the late seventies. 1978 and 1979 were the best sign-up years for the L. 1011 since initial orders were here were more L. 1011s sold to US operators than there were DC-10-10s. What happened then, however, is that McD charged away with the wide-bodied trijet stakes as DC-10-1O operators, who either demanded longer range or upgraded from DC-8 and 707 narrow-bodies on international routes, simply ordered the Series 30 DC-10. In short, there were only so many aircraft required for the medium-range wide-bodied trijet scenario and by 1976 most airlines had more than their fair share of transports in this category. Hence a dwindling order book and a Tristar program rapidly heading for a re-run of the early seventies nightmare of a government bailout.

Enter the long range Dash 500 Tristar.

A long range version of the aircraft was proposed to carriers in 1975 designated the Dash 500. Orders were soon taken from both Delta and British Airways; original Tristar operators with great respect for the type. The real boost, both in monetary and moral terms, came in April 1978 when Pan American placed orders on 12 aircraft with options on 14 more. A substantial order in anybody’s language taken on commercial transport back in 1968. These new orders required a rapid rebuilding of the Tristar production rate. In less than 18 months production soared, with eight aircraft being delivered in 1978 and 29 planned for 1981.

The rapid build-up created difficulties leading to excess costs, primarily attributable to sharply increased manhours on aircraft in production during 1979. Shortages of parts and raw materials, aggravated by the high level of activity throughout the aerospace industry, proved particularly burdensome. In many ways this led to problems associated with providing sufficient aircraft to meet customer delivery demands. As an example, back in 1977, lead times on titanium forgings were about 34 weeks. By mid-1980 they were 180 weeks. The time required to receive titanium extrusions went from 16 to 72 weeks. A similar situation existed for aluminium forgings and hundreds of other materials and parts. This situation has been relieved slightly of late owing to the general economic downturn and a consequent reduction in material demand.

The principal engineering differences of the Dash 500 from the basic Dash 1 Tristar are:

• Remove fuselage sections fore and aft of the wing to reduce fuselage length by 13. 5 feet.

• More powerful engines, from 42,000 lb to 50,000 lb thrust. Increased fuel capacity with additional tanks located in the wing centre section.

• Location of galley services on the main deck and removal of the galley lifts.

• Enlarged forward cargo compartment and cargo door.

• Strengthening of airframe structure and landing gear to allow for an increased maximum gross takeoff weight of 496,000 lb.

The most important consideration in the development of the Dash 500 was the achievement of maximum commonality with the basic L. 1011 series to minimise initial aircraft costs and the impact on customer resources. At the same time, by creating an entirely new marque of the Tristar, Lockheed was able to undertake sufficient re-design to incorporate many new features to enhance fuel economy.

For example, longer wings can mean less drag, resulting in decreased fuel consumption. However, adding wing tip extensions causes significant increases in design loads and usually requires an extensive re-design of the entire wing structure. Lockheed overcame this problem by designing an exclusive system of active aileron controls that relieve these loads thus permitting the extension of each Tristar wing by 4. 5 ft without the need for a costly re-design. Controlled by computers, these ailerons automatically deflect upward or downward to reduce the structural loads on the extended wings.

Lockheed’s Flight Management System (FMS) is another fuel conserver. Programmed to fly the most economical flight possible, the FMS computer senses altitude, speed and a variety of other flight factors, and then automatically controls the engine throttles for the best fuel efficiency at all times during the flight from takeoff to landing.

Pan American has taken delivery of the first Tristar 500 with extended wings and active aileron controls as well as a version of the FMS. The PanAm aircraft are also equipped with Rolls-Royce RB. 211-524B3 engines, appearing for the first time on a production aircraft. These new engines will provide an additional 3 per cent increase in fuel efficiency.

From the day when the first long-range DC-10-30 entered airline service, it was obvious that Lockheed would need a similar capability to Tristar if it was to remain a viable builder of passenger jets. The long delays in getting the Dash 500 into production resulted directly from the company’s awesome monetary problems left over from the early seventies. Without the necessary finances for an extensive R&D program, Lockheed had to make do with its medium-range models, waiting till the economic tide had improved sufficiently to enable investment in what is now the saviour of the Tristar line.

There are four primary versions of the L. 1011; in genetic order, they are:

• L. 1011-1. Lockheed’s first Tristar version, in service since 1972. It can carry up to 400 passengers over 3500 statute miles, which makes it ideal for continental North American operations. Dash 1 is in operation with TWA, Air Canada, All Nippon Airways, British Airways, Delta, Eastern, LTU, Cathay Pacific and AeroPeru. This version is powered by Rolls-Royce RB. 211-22B of 42,000 lb thrust.

• L. 1011-100. It is an extended-range version of the Dash 1 with a 1000-mile range and a full passenger load. Can fly trans-Atlantic missions and has been in service since 1975. Operators include Cathay Pacific, Air Canada, Gulf Air, TWA and Delta.

• L. 1011-200. Same as the Dash 100 except for the use of a more powerful RB. 211-524B engines of 48,000 lb thrust. This version enables operation from hot-and-high airfields which is a boon to operators in the Middle East. This model has been in service since 1977 with Saudia, British Airways, Gulf Air, Trans Carib Air and Delta.

• L. 1011-500. Last, but not least, the Dash 500. Features extra fuel capacity enabling a maximum passenger payload range in excess of 6000 miles. The fuselage is 13. 5 ft shorter and the wing span is 9 feet longer. Accommodation varies between 230 and 330 passengers and is powered by three RB. 211-524B4 turbofans of 50,000 lb maximum thrust.

Not resting on its laurels, Lockheed also is planning for some additions to its current Tristar family, including a long-fuselage long-range version that will ultimately provide competition for the 747. Among the new versions under discussion are:

• L. 1011-250. Same external fuselage dimensions as the basic Tristar, but with the added wing span of the Dash 500, a higher gross weight and increased fuel capacity. Being proposed for nonstop missions of upwards of 5200 miles.

• L. 1011-300. Stretched fuselage version for medium-range routes could carry 70 to 100 more seats than the basic model.

• L. 1011-500F. This will be an all-cargo version of the Dash 500.

• L. 1011-500VLR. A very long-range version of the Dash 500; would have the same external dimensions as the current model but incorporate increased fuel capacity. Lockheed’s answer to the 747SP.

Probably the most realistic, as future projects go, of these proposed aircraft will be the Dash 500VLR and the Dash 300. The latter aircraft could carry standard 747 passenger loads over medium ranges with the economy of three engines. The former, of course, could cater for the very long-range sectors that may become more viable as certain areas of the world become less attractive to overfly or refuel in as the decade progresses. I am sure most readers wouldn’t have to spend long looking at a map of the world to see the point I make!

In conclusion, one can only say that the Tristar program has come of age with the introduction of the Dash 500. Certainly, if both Rolls-Royce and Lockheed hadn’t suffered the economic traumas of the early seventies then the Dash 500 would have been with us several years earlier. With the Dash 500 rapidly becoming the standard DC-8/707 replacement the future is certainly looking bright for Lockheed’s latest Tristar.