Why The Boeing 777X Has Such Large Engines

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The Boeing 777X is the newest aircraft to be developed by Boeing with a planned entry to service in 2026 with launch customer Lufthansa. The huge twinjet is the longest commercial jet ever built with a staggering length of 251 ft 9 in (76.73 m) for the 777-9, making it even longer than the Boeing 747-8 or Airbus A380. With a capacity for upwards of 425 passengers (395 on the 777-8), the widebody will be powered by two General Electric GE9X engines, the world's largest jet engine.

Boeing 777 Launch Customer(s) United Airlines Manufacturer Boeing Aircraft Type Widebody First Delivery May 15, 1995

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With such a large fuselage and capacity on a twinjet, the 777X needed to go big with its engines to achieve the necessary performance. Featuring a fan diameter of 134 inches and thrust rating of 110,000 lbf (490 kN), the GE9X holds the record for being the most powerful commercial jet engine after it managed to reach 134,300 lbf during testing. Along with delivering a range of other efficiency and reliability enhancements, the GE9X promises to be a game-changer for the long-haul market.

How Big Are The Boeing 777X's Engines?

The short answer is that the GE9X is the largest commercial jet engine ever built. With a fan diameter of 134 inches, this is six inches larger than the GE90 engine which powers the Boeing 777-200/300. With an overall engine diameter of 184 inches, each engine weighs approximately 21,000lb (9,525 kg).

Interestingly, earlier designs of the GE9X featured a smaller fan diameter, but this was eventually bumped up by around five inches to its current size. The GE9X features 16 fan blades, which is six fewer than the GE90, made out of carbon fibre composite material to lower their weight. With a high bypass ratio of 10:1, according to Key Aero, the GE9X can ingest and propel up to 3,850lb (1,746kg) of air every second when at maximum thrust.

There is an oft-repeated claim that a GE9X engine is wider than the fuselage of a Boeing 737. While this isn't quite true in terms of fan diameter (134 inches), when including the engine's nacelle, its diameter is a gargantuan 184 inches. This makes the engine's overall structure significantly wider than a Boeing 737's fuselage, which has a diameter of 148 inches. It would also put the engine at a foot taller than an NBA basketball hoop.

Why The 777X Has Such Large Engines

Given the 777X's size and considerable MTOW of 775,000 lbs (351,500 kg), Boeing needed an engine capable of delivering the necessary thrust for takeoff. Rated at 110,000 lbf (490 kN) of thrust, this is actually lower than the GE90-115B (115,000 lbf). However, as explained by GE9X programme manager Ted Ingling, this is because the 777X's highly efficient design means it doesn't need more power than it has.

The aircraft's 5,025-square-foot wings can deliver extra lift that also helps the 777X reduce its fuel burn by up to 20% compared to the 777-300ER. Ingling told Key Aero that Boeing had done "a marvellous job in getting the lift drag on the aircraft such that the engine thrust required to fly the bigger 9X-powered aircraft doesn't have to be as high as for the 777-300ER."

GE9X

GE90-115B

Aircraft

Boeing 777X

Boeing 777-300ER/200LR

Takeoff Thrust

110,000 lbf (490 kN)

115,300 lbf (513 kN)

Fan Diameter

134 in (3.40 m)

128 in (3.25 m)

Bypass Ratio

10:1

9:1

Fan Blades

16

22

Weight

21,000 lb (9,525 kg)

19,300 lb (8,750 kg)

In comparison, the Airbus A380's two engine options - the Engine Alliance GP7200 and Rolls-Royce Trent 900 - deliver around 75,000 lbf of thrust, while the Boeing 747-8's GEnx-2B is rated at 66,500 lbf. However, in the case of both these aircraft, they have four engines powering them and not two.

Related GE9X: The Engine That Will Power The Boeing 777X

Boeing and GE Aerospace have continued to work together on the 777 program, with the latest aircraft, 777X, being powered by the GE9X.

Posts 7 The 777X Will Be Surprisingly Quiet

The GE9X will be impressively quiet for such a mammoth engine, improving the cabin experience for long-haul passengers. It will have a bypass ratio of up to 10:1, which not only improves efficiency but helps reduce noise by ensuring more air can flow around the core. According to GE Aerospace,

"Per pound of static thrust produced, the GE9X is the quietest turbofan engine GE Aerospace has ever produced, and is designed to meet current and anticipated next level of noise certification standards on the B777X Family."

Jet engines typically use chevrons to help reduce noise emissions, but the 777X does not feature any, despite it being part of the original aircraft design. Instead, the engine incorporates new nozzle design technology that removes the drag penalty of chevrons to ultimately push up its efficiency.

This is in addition to a honeycomb acoustic treatment in the engine's exhaust system, a process that entails drilling thousands of minuscule holes in the composite skin to capture noise. With all of its advanced features, the GE9X will deliver around 10% better fuel efficiency than the GE90 engine and, despite its immense size, will be the company's quietest engine per lbf per decibel.

GE Aerospace's Most-Tested Engine Ever

Engines undergo an extensive testing process to ensure they can perform reliably and safely. According to GE Aerospace, the GE9X has been through "the most rigorous testing program of any GE commercial aircraft engine in history." This follows 27,000 cycles and 17,000 hours of testing, also including 1,600 cycles of dust-ingestion tests. As detailed by Tyler-Blair Sheppard, the head of marketing for the GE9X,

"We've run the heck out of the engine, and customers have been really impressed by the dust test data coming back, which is the equivalent of almost three years of normal use on the engine."

Over the course of its certification journey, the GE9X took part in 72 test flights involving over 430 hours of flight. The Boeing 777X would make its maiden flight in January 2020 with an almost four-hour journey from Paine Field to Boeing Field.

During a ground test in 2017, the GE9X recorded 134,300 lbf (597 kN) of thrust that would later be recognized as a world record by the Guinness World Records. Boeing has occasionally halted 777X test flights to overcome engine hurdles, but the GE9X would obtain its Federal Aviation Administration (FAA) type certification in 2020.

GE9X Production Begins

As of last month, the engine is in full production ahead of the 777X's entry to service. Brand-new engines are rolling off the production line at GE Aerospace's facility in Durham, North Carolina, where they are being loaded onto trucks for testing in Ohio. After this, they will then make their way to Boeing's Everett facility ahead of their assembly onto 777X airframes.

According to the GE9X programme head, Cristina Seda-Hoelle, the enginemaker will be "aligning production with Boeing's production of the 777X." Despite a series of setbacks delaying the 777X's entry-to-service by several years, the aircraft finally looks set to debut within the next 18 months, and Boeing will need production to be on point to meet delivery targets.

GE Aerospace will also be investing over $1 billion over the next four years to enhance its maintenance, repair and overhaul (MRO) capabilities for GE9X customers. This will cover the company's MRO shops across the globe to ensure the 777X's global customer base can benefit from its technical expertise.

Related How Different Will The Boeing 777X Be From The 777?

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Posts 14 How Many Orders For The 777X?

According to the latest figures from Boeing, there have been over 480 orders for the passenger Boeing 777X, as well as an additional 59 commitments to the freighter version. The 777X was initially marketed for a 2020 entry-to-service date, but the program has been hit by repeated setbacks that make 2027 the likeliest entry date. The 777X includes two variants - the shorter 777-8 and the more popular 777-9 - as well as the 777-8F freighter version.

The vast majority of orders are for the 777-9 variant at around 440, while the 777-8 has attracted over 40 orders. The largest customers for the plane are currently Emirates and Qatar Airways, while launch customer Lufthansa will be the first airline to operate the 777X, with the German carrier expecting its first 777-9 delivery in late 2026.

Variant

Firm Orders

777‑8

43

777‑9

439

777‑8F

59

Total

541

With almost 550 total program orders when including the 777-8F, this would equal almost 1,100 commitments to the GE9X engine. GE is the third-largest commercial engine manufacturer in the world, with Pratt & Whitney and CFM International remaining the two largest producers.