The Ecoliner was a concept for a next-generation jumbo that reimagined the 747/A380 size class with only two engines. It’s essentially a fictional Boeing “Y3” design put forth by enthusiasts and engineers as an “eco-friendly” large airliner. The design features a full double-deck fuselage (like an A380) but powered by two giant high-bypass turbofans.
Efficiency Aims: The Ecoliner aimed to carry 400–500 passengers with dramatically improved efficiency. By “turning the 787 into a double deck,” the idea was to double the seating of a 787 while achieving similar economics per seat
foundandexplained.com
. This could “greatly plunge the seat price,” meaning airlines could have 747/A380 capacity for roughly the operating cost of a much smaller twinjet
foundandexplained.com
. In theory, that yields major fuel burn and cost savings per passenger – the holy grail for airlines.
Design Tricks: To solve the engine-out problem, one proposal for Ecoliner was to include a small third engine (or auxiliary thrust unit). As noted, “contrary to what most believed the concept Ecoliner was a trijet, with a ~35k lbs engine in the tail to get one-engine-out take-off” performance
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. This tiny third engine would only be used for extra boost on takeoff or if a main engine fails, allowing the main two engines to be more “normal” in size. Such creative solutions underline how challenging it is to make a viable twin-engine superjumbo – it might not truly be a pure twin in the end.
Reality Check: The Ecoliner remained a paper (or rather, digital) concept. Boeing never built it, and it existed primarily in CGI renders and forum discussions. It does, however, encapsulate the optimism that advanced technology (new engines, materials, aerodynamics) could overcome the traditional need for four engines in a jumbo. It showed that, on paper, an aircraft slightly smaller than an A380 could achieve 25–30% lower fuel consumption than a 747-400, by using two efficient engines and lightweight construction (as estimated by its proponents).