I have always been a fan of all things esoteric, the unique, and perhaps even the underdog. Engineering oddities fascinated me from a young age; if it was different or somewhat outlandish, I was hooked. For that reason, it’s probably no surprise to many people that the aircraft I adore more than all others (yes, even more than Concorde) is the Lockheed L-1011 TriStar.
However, I can take things a step further, because for me, this is more than an aircraft; it represents the engineering prowess of hundreds of engineers – one of whom I happened to know very well. A man who was lucky enough to spend a lifetime in aviation working for some of the most storied aeronautical firms in history, such as Avro Canada (later Hawker Siddeley), Convair, De Havilland Canada, and Lockheed. Prior to his death in 2013, this engineer described the L-1011 as his “magnum opus”, his greatest achievement as an engineer and the work that he was most proud of.
(Clicking Play on the media file above will play the L-1011 theme song that Lockheed commissioned to advertise the TriStar to potential airline customers)
While much has been written about the failures of the L-1011 to gain a foothold in the commercial market, I have always found the battle between Lockheed and McDonnell Douglas to be a fascinating business case, a prime example of market saturation and what ultimately lead to the undoing of both companies commercially. However, it is also interesting to look at how two companies approached an identical brief from one visionary American Airlines executive. Before we take a look at the TriStar in detail, it is perhaps worth a brief history lesson.
The late 1960s was a time in which just about anything seemed possible. The stars – man was moving ever closer, using his knowledge to realize dreams that had been held for centuries. The technology of the space age was being utilized to help improve mobility on Earth. One approach to meeting the needs of a more mobile society was that taken by Lockheed – the result was quite simply the most advanced first generation wide-body aircraft – a new stage in intercity and intercontinental transportation was born.
In the late 1960s, passenger traffic in North America was growing at an astronomical rate – in order to cope, Boeing had launched the 747, a plane designed largely for Pan Am and sized for their projected passenger growth figures in the upcoming decade. While very few airlines had both the passenger numbers and long-range routes to support the massive aircraft, no airline could afford not to be seen with 747s.
However, it was Frank Kolk, American Airlines vice president of engineering, who clearly saw that the 747 was far too large for American, yet the benefits of a wide-body aircraft powered by highly efficient, high-bypass turbofans was a tantalizing prospect. Despite envisioning the aircraft as a wide-body, twin-engine aircraft, the engine technology of the time as well, as the FAA’s 60 minute rule, mandated a three-engine layout. There were two major responses to Kolk’s brief, from Lockheed and Douglas. Despite having considerable experience with piston engine aircraft, Lockheed had been absent from the commercial market since the L-188 Electra debacle (customer confidence is often lacking when your aircraft mysteriously come apart in midair). Douglas had the DC-8, which was beginning to get rather long in the tooth, and the Super 60 Series orders were drying up.
Having lost the US Air Force’s contract for a strategic air lifter to Lockheed, Douglas had a surplus of engineering talent and a serious cash deficit – the McDonnell Douglas merger was about a year away. The DC-10 would be the first major project to develop from the newly merged company. Unfortunately, McDonnell had no experience in selling commercial aircraft – this was a huge issue – and previous Douglas products were developed with Douglas family money; when cost overruns occurred, they were either paid out of company funds, or in cases such as the DC-8, Donald Douglas himself would cover the costs.
McDonnell felt that the DC-10 needed to be built to a very firm budget, and cost overruns were unacceptable – even at the expense of safety. When this is taken into account, one begins to understand how the groundwork for incidents due to design defects with the DC-10 was laid even before the first metal was cut for the aircraft. A classic example known to most is the cargo door debacle that led to the famous “Applegate Memorandum“…but that is another story for another time.
The L-1011 and DC-10 followed the same basic brief, but the engineering methods for each aircraft were extremely different. McDonnell Douglas tended to be more conservative in its approach to building its first wide-body aircraft – in many ways, the DC-10 was simply DC-8 technology that was enlarged and modernized in certain respects. Lockheed, on the other hand, felt that the key to success in the market was to take the most advanced technology of the day and when that technology was lacking, Lockheed created it.
With every aspect of the TriStar – from its Rolls-Royce RB211 turbofans, to the autoclave bonding method of fuselage assembly, as well as the avionics…Lockheed had something to prove. The executive team in Burbank felt that the same people who delivered aircraft like the U-2, L-100 Hercules and the SR-71 could also build a commercial aircraft that made the 747 look quaint by comparison and could perhaps even eliminate the DC-10 before it came off the drawing board.
The false belief that technology sells was something of a misnomer. History has often dictated that airlines don’t purchase the aircraft; they purchase the manufacturer. Case in point: United Airlines had demonstrated significant interest in the L-1011 TriStar. The engineering base in San Francisco felt that the TriStar was a superior product to the DC-10 and the general feeling was that Lockheed had made the sale.
At the time, Lockheed’s Daniel Haughton was ready to add United to the launch customer list. Charles Tillinghast of TWA was ready to hand over some of TWA’s early delivery slots to United. It wasn’t to be. The L-1011 may have had an edge technologically, but United’s management felt that Douglas inspired more confidence as a company (indeed, this has been proven when you consider what Airbus went through in order to penetrate the U.S. commercial market).
American Airlines, the catalyst for the entire L-1011/DC-10 sales race, played each manufacturer off the other…in the end, the goal was to get McDonnell Douglas to lower the DC-10 selling price, which they did. Lockheed responded by acquiescing to demands placed upon them by Eastern Air Lines to further lower the price again, thus undercutting the DC-10.
It is interesting to note that while it is widely acknowledged in the industry that Boeing actively sought input into the design of the 777 by creating the “Working Together” group in the early 1990s, Lockheed actually preceded the concept by about 30 years. Once launch customers for the TriStar were clearly defined, Lockheed made an effort to work closely with customers to define details of the new aircraft.
With both United and American out of the picture, there was considerable freedom throughout the design process. For example, the galley arrangement and layout was driven by input from Air Canada who felt that turnaround times could be accelerated by having a dedicated galley service door. Other details unique to the TriStar that later made their way on to other wide-body aircraft were a selection of cockpit instrumentation – traditional round dials or innovative vertical tape instruments.
Eastern and TWA pushed for on-board diagnostics and self-sufficiency wherever possible – this led to considerable use of built-in test equipment that exceeded that of the DC-10. Other operators consulted on cabin layout and design and again we come to another interesting footnote in the history of the TriStar.
In designing the passenger cabin, Lockheed sought to make the aircraft feel more like a spacious home and eliminate the “tube” feeling that was so common on aircraft like the DC-8 and 707. Whereas the DC-10 had a rather simple interior design, the TriStar had its entire interior concept conceived by the industrial design firm of Sundberg-Ferrar. The unique waffle grid ceiling lighting was considered to be highly advanced – cold cathode lighting or “luminaires.”
At each of the entry doors, small recessed spotlights provided a warm, intimate, and unique cabin atmosphere. Then of course, there were other unique aspects to the TriStar cabin – initially planned for production aircraft was a self-tinting window (eat your heart out 787). Predating the 787 by almost 40 years, it was thought that passengers could control the tint of their window by using a small control panel in addition to the window shade. Ultimately deleted on cost grounds, it is an interesting example of history repeating itself since this is a highly-touted 787 feature.
Since the L-1011 was born prior to airlines charging for checked baggage, and passengers didn’t feel the need to bring massive carry-on items with them, the L-1011 featured compact overhead bins that were (to quote advertising of the day) “sized for a lady’s wig box.”
One interesting aspect of the L-1011 design was that it was capable of handling more passengers than the DC-10. The DC-10 had a maximum certified passenger capacity of 380 passengers, whereas the L-1011 TriStar was capable of seating up to 400. Additionally, Lockheed designed the TriStar fuselage to prevent any entry door being over the wing, thus easing evacuation slide design. The DC-10 had two doors mounted centrally over the wing. This video clip depicts the complicated DC-10 slide design for over-wing evacuation.
Various Lockheed passenger cabin configurations are depicted below:
(All diagrams above sourced from the L-1011 Interior Configuration Handbook – Lockheed-California Company)
Additional storage could be found beneath passenger seats by flipping the seat cushion up – a small storage container was located below and was designed to hold a pillow and blanket. The TriStar galley was always a fascinating study – Lockheed claimed to have patented the concept of a lower deck galley and indeed several airline employees that I have spoken to with experience on all three first-generation wide-body aircraft have agreed that the L-1011 had by far the most spacious and user friendly galley.
Two small lifts (Lockheed was careful not to refer to them as elevators due to potential confusion with the aircraft control system) connected the lower deck galley to the passenger deck. The goal was to “take the kitchen out of the living room.”
Of course, the downside to this layout was that considerable cargo room was lost – a fact that Lockheed recognized and later corrected on the L-1011-500, which despite being considerably shorter in length than the regular TriStar, had much more cargo room since the galley was relocated on to the main deck.
In reviewing considerable marketing and engineering material for the TriStar, it is interesting to note the very high level of optional customization that Lockheed offered customer airlines. The flight deck was offered in a choice of three colors – blue, olive (a particularly horrible option), and gray. Most customer airlines selected gray and a few selected blue. To the best of my knowledge, no TriStar was ever equipped with an olive green flight deck, although it would have been an interesting sight to see.
Images: L-1011 Interior Configuration Handbook – Lockheed California Company
The TriStar is best remembered for its advanced avionics – a completely clean sheet design that was far advanced over the DC-10 and the 747. The TriStar avionics fell under the title of AFCS (Avionic Flight Control System). The AFCS bundle included the APFDS (Autopilot Flight Director System), SCS (Speed Control System), PFCES (Primary Flight Control Electronic System), Triple Inertial Navigation System, SAS (Stability Augmentation System), and the DLC (Direct Lift Control). Included with all aspects of the AFCS subsystems was Lockheed’s advanced BITE (Built In Test Equipment) systems that provided constant fault monitoring, recording, and output tests on various subsystems.
One highly touted feature of the AFCS system was the CAT-IIIB Autoland system that was installed and certified right from day one. A selling feature for airlines that operated in environments with frequent weather issues, the CAT-IIIB Autoland was capable of bringing the TriStar down to land with only 150 feet of visibility. The technology was exceptionally well engineered and very reliable in service.
Lockheed’s goal was to develop an automatic landing system that was as seamless and gentle as a human. A joint effort from Lockheed, Lear-Siegler, and Collins (now Rockwell-Collins) resulted in a truly great avionics platform that outperformed that of the 747 and even Concorde. However, it was on May 25, 1972 that the system truly came of age when a completely automatic flight from Palmdale to Dulles International was completed, demonstrating the capabilities of the advanced avionics package.
Takeoff through climb, cruise, descent, landing, and roll out was done without a human hand on the controls. The system was monitored on the flight deck through a display that annunciated the 12 modes of the AFCS system.
I am the first to admit, the TriStar was far from the perfect aircraft – Lockheed was slow to adapt the aircraft for long-range operations and the DC-10 already had the Series 30 available by the time the TriStar was entering service in its initial guise. One can argue that the TriStar 500 was a nothing more than a Band-Aid solution. The DC-10-30 had the range and capacity needed to be profitable and it had a seven-year sales lead. The -500 was impressive in other areas, with technologies that have not been duplicated even today, over 35 years after first flight.
The L-1011-500 program was launched by British Airways in the mid-1970s. Without delving into a complete analysis of the -500 differences, the basic aircraft was shorter than a standard TriStar by about 14 feet. This resulted in the smaller two Type I emergency exits being deleted. Maximum certified passenger capacity was 315, although this carrying capacity was never exploited by any carrier. By the time the aircraft entered service in 1979, it benefited from almost a decade of advances in avionic technology and, Lockheed being Lockheed, they worked to exploit this as much as possible. In creating the -500, Lockheed refined the aerodynamics of the TriStar by adding a fillet under the #2 engine intake (the “Frisbee” fairing, named after Lockheed Director of Engineering Lloyd Frisbee) which reduced noise in the aft cabin.
In addition to the Frisbee fairing, Lockheed also extended the wingspan of the TriStar and introduced a system of active ailerons, known as the ACS – Active Control System. This early form of fly-by-wire technology combined three accelerometers located in the tip of each wing and one in the tail. The data collected from the accelerometers was fed to the Active Control System control unit located in the forward avionics bay to systematically deflect the outer ailerons to redistribute lift forces over the wingspan of the aircraft, improving ride quality for passengers and also, decreasing fuel consumption in some cases. Also included in the -500 were higher thrust Rolls-Royce RB.211-524 engines that were initially rated for 50,000 lbf. and later the uprated RB.211-524B4 engines were installed which brought thrust per engine to about 53,000 lbf.
Finally, the L-1011-500 also introduced the Performance Management System – an early attempt at an integrated Flight Management System. Operational analysis of the TriStar fleet by Lockheed resulted in a noticeable pattern of excessive throttle movements in order to maintain an optimum cruise Mach number. While some airlines generally would accept a higher Mach cruise number at the expense of fuel burn, Lockheed developed the PMS to maintain an exact airspeed by gradually varying the aircraft attitude. In the event of an excessive speed condition, the PMS would command a slight nose-up attitude adjustment. In the event of speed loss, the opposite would occur.
The system was limited to an adjustment of no more than 50 feet in any direction. The design goal was to increase engine life, decrease thrust variations and provide a more relaxed working environment for the flight crew. The PMS effectively realized these design goals and the TriStar 500’s PMS was made available to older aircraft as an available retrofit. This system was copied by McDonnell Douglas for the MD-80: The “PERF” mode on the MD-80 Digital Flight Guidance Control Panel (DFGCP) did the same thing, however McDonnell-Douglas failed to provide a tight authority limit and many pilots find that the PERF setting on the MD-80 leads to a noticeable see-saw motion.
The Lockheed TriStar is an interesting case study in what can happen when two manufacturers (in this case, Lockheed and McDonnell-Douglas) attempt to split a market that simply could not support both aircraft. While there is no dispute that L-1011 was the more advanced of the two aircraft, and that the TriStar was easily the most advanced first generation wide-body aircraft, it is sad that this was the final aircraft that Lockheed would offer to the commercial market.
One very interesting aspect of the TriStar program was that Lockheed had concurrently undertaken many derivative design studies of aircraft that could be based on the basic TriStar airframe and wing. These design studies consisted of several wide-body, twin-jet aircraft designs, and a fascinating stretched TriStar design that would have had two underwing RB.211 engines as well as two rear fuselage mounted RB.211s. This design study modified the basic L-1011 landing gear from two four-wheel trucks into a 777-style six-wheeled truck.
As we all know, these design studies came to nothing. The failure of the TriStar program drove Lockheed out of the commercial business and very nearly to the brink of bankruptcy for the second time. The Lockheed bribery scandals did nothing to improve customer relations and Lockheed did not have the funds to pursue any of these designs. Had Lockheed pursued the twin-engine variants of the L- 1011 design, the company would have been able to beat Boeing to market and possibly drive Airbus out of the market entirely.
As time has gone by, it is interesting to think about where we would be today if the DC-10 had failed or never flown, Lockheed remained in a commanding position in the commercial market, and Boeing and Airbus were not the dominant players that they are today. Consider for a moment – if Lockheed had been able to capture the DC-10’s market share as well as maintaining its own, the MD-11 would never have evolved, and the MD-80, MD-90 and MD-95/717 would probably never have been built since McDonnell-Douglas’ already precarious financial position would have completely imploded by the failure of the DC- 10. There is a very good chance Airbus would not be around – Lockheed’s pursuit of a wide-body twin-jet would have destroyed the A300 in North America and very likely in Europe and the Asia-Pacific market as well.
It is safe to say that the L-1011’s success would have altered the landscape of today’s commercial aviation market significantly. It’s an interesting study in what might have been. Another aspect that needs to be considered – the ever-popular family of Rolls-Royce Trent engines owe their existence to the L-1011 program. Lockheed and Rolls-Royce both suffered through the development process of the RB.211, and while it took a while to mature, the three-shaft concept certainly has been proven to be a true success story. The RB.211 has an exceptional history of performance, reliability, and durability. If Lockheed had given up on the L-1011, the RB.211 would have been flushed as well, ergo Pratt & Whitney and General Electric would basically own the commercial market.
The entire Trent family of high-bypass engines, as well as other offshoots such as the IAE V2500, would have evolved into completely different machines. The 757 would have never flown with Rolls-Royce power. The A330 would only have two (PW4000 and CF6) engine types slung under its wings. The A380 would be equipped with purely Engine Alliance GP7000 series turbofans. We fail to realize just how much the current world of commercial aviation owes to Lockheed, the TriStar, and Rolls-Royce.
One final note of interest – while the TriStar was the first wide-body aircraft to crash (Eastern Air Lines Flight 401), no passenger was ever lost due to a design defect that impacted safety. That’s something that cannot be said for any other wide-body aircraft from the same time frame.
Regardless of the business case, I will always have a special place in my heart for the TriStar. It may not have been a market success, and it certainly wasn’t perfect. But as far as I am concerned, a more beautiful aircraft has never been built. All the technological innovation that Lockheed brought to fruition on the TriStar is a testament to the many men and women who devoted their efforts to creating the most advanced wide-body aircraft of the day, and what can happen when we push the limits of what is believed to be possible, use the most advanced technology and, when it is lacking, create it to make a product that is truly different, innovative, and with a character all its own.