Boeing’s Abandoned 777 Trijet: What Might Have Been

During the back half of the 1900s, Boeing studied several intriguing concepts that never got off the ground. However, in some cases, their studies would ultimately prove valuable in charting a firmer course for the plane maker.

One of those concepts was a Boeing 777 with three engines, a trijet, and a T-tail, similar to the popular series released by McDonnell Douglas.

But what was this concept aircraft? Why was it studied? Why wasn’t it released? Was it ultimately the right decision from a manufacturer trying to wow its customers with the next big thing?

Boeing Attempts To Compete With Emerging TriJets

In the late 1970s and early 1980s, Boeing released new aircraft to replace older models and compete with new rivals in the sector.

During this period, Boeing released the 767. It was designed to compete with the Airbus A300. Additionally, Boeing introduced the 757, also intended to help replace some of the ageing 727s.

Thanks to rapid technological evolution, Boeing needed to outdo its previous aircraft faster while watching emerging manufacturers that could steal market share.

One sector the company believed it lacked was the one occupied by the DC-10 or Lockheed TriStar.

In other words, it believed there was a gap between the newly released 767 series and the queen of the skies, the quad-engined 747, which was taking the industry by storm.

Boeing Thinks A TriJet Is The Answer

The obvious solution seemed to be an aircraft with not two, not four, but three engines. At the time, three-engine aircraft made a lot more sense than they do in the 21st century.

With ETOPS regulations restricting twin-engined aircraft from long overseas flights at the time, trijets offered a happy medium for airlines that wanted an aircraft capable of crossing oceans without the size and operating costs of the 747.

Boeing Begins Work On A 777-100, A TriJet

Therefore, around the time of emerging competition, Boeing began drawing up concepts for such an airplane that would slot between the 767 and 747

Boeing identified this concept as the 777-100 and conceived it as a trijet. Using the 767 as a base, the aircraft would be a scaled-up version of this series, with the same wide body and nose but a third engine on the tail.

Inspiration would no doubt come from other plane makers moving ahead with such trijet variants, and Boeing wanted to ensure it wouldn’t miss any available market. At the time, it had undoubtedly enjoyed capturing most of the long-haul demand thanks to its jet-powered aircraft.

S-Duct For The 777-100?

Like the Lockheed TriStar, the 777 Trijet was planned to feature an S-Duct for its third tail engine, though concepts were also drawn up for a straight-through engine, which would have made it look more like, say, the DC-10.

The S-Duct meant that while the intake was above the fuselage, the exhaust would be at the rear of the aircraft, with the entire engine tube bent into an S shape, unlike traditional engines, which ran straight through.

This design had several benefits: the third engine would be closer to the ground, making it easier to service, and the technique reduced the Trijet’s overall drag, unlike the straight-through third-engine design of the Douglas DC-10 and MD-11.

Boeing wanted to make sure it got the aircraft right if it proceeded with such a trijet. This era marked a time when Boeing led the way in manufacturing standards and innovation.

ETOPS Removes The Need For A 777-100

However, as with the biggest changes to airliner design and the aviation industry, the decision not to proceed with the 777 trijet program came primarily from lifting ETOPS regulations on the allowed overseas flight distances of twin-engine planes.

As a result, the trijet concept became obsolete, as any twin-engine aircraft could match its performance at a fraction of the cost.

While Boeing’s twin-engined programs, such as the 757 and 767, saw wild success with this new development, interest in a trijet from the American aircraft manufacturer dropped.

Add this to the fact that trijets were very complicated to design and maintain. There were several important reasons Boeing never proceeded with such a design.

A Gap In The Market Is Still Present

Nevertheless, Boeing still faced a gap in its fleet between the 767 and 747. While ideas circulated about a stretched 767, airlines clearly wanted a whole new aircraft.

Key airline executives made this opinion clear on several occasions in close communication with the American plane maker. Thus, Boeing returned to their 777 concept with some game-changing refinements.

This time, Boeing went back to the drawing board and made the most significant change: removing the third engine and, with it, the plane’s trijet nature.

As a result, the 777 as we know it today was born. The 777’s life is set to be extended for decades with the newest iteration in the series: the upcoming 777X.

Was It The Right Decision For Boeing?

Most would argue that Boeing not proceeding with a three-engine 777-100 was the right decision. While trijets are spectacular, launching a 777-100 could’ve significantly altered Boeing’s current 777 program and widebody offering.

The development of ETOPS on twin-engine aircraft saved Boeing and eventually led to the study of a much more refined and efficient 777, known today as the 777-200 and 777-300 series.

The success of the refined 777 cannot be overstated, and with the upcoming launch of the 777X, this program’s life will extend toward the end of this century. Had Boeing proceeded with a 777-100 and never released the current iteration, you’d be hard-pressed to find anyone who would agree that a similar fate would occur.