Why Boeing Moved The Engines On The 747-8

It is now ten years since the Boeing 747-8 Intercontinental was revealed. While we look back at the journey of the widebody and the whole 747 series, we thought we’d take a look at why the latest variant’s had its engines moved.

Nippon Cargo 747-8
There is good reasoning for the change in engine placement on the 747-8. Photo: Boeing

Practical solutions

Pilot Anas Maaz explains that engines were hung on pylons that extended downwards on older aircraft for a valid reason. If engines were too close to the wing, the airflow over the wing could be drastically impacted. However, this issue is solved if the engines are fixed on a long pylon as it ensures that it is not too near the wing. Moreover, the pylon acts as a vortex generator when in flight. This process adds energy to the boundary layer, which then improves the stall features of the plane.

Rossiya boeing 747-400 british airways
The long pylons on the 747-400 provide an important role. Photo: Getty Images

Adapting to the needs

The 747-400 has three engine options: the Pratt & Whitney PW4000, the Rolls-Royce RB211, and the General Electric CF-6. However, the engine that was being fitted on the 747-8 created a new problem. The large size and design of GE’s GEnx meant that the setup had to change.

“[The previous] engines were all built in the late 70s and 80s and were second-generation high bypass ratio engines. The 747–8 is fitted with new generation General Electric GEnx engines, which are much larger in diameter with a higher bypass ratio than the engines used by the 747–400s. This meant that the engines can no longer be held on long pylons as this would reduce the ground clearance,” pilot Maaz shares via Quora.

“So, the engines are mounted on shorter pylons. To solve the problem with the wing boundary layer energy loss due to close-fitting of engines, strakes are placed on the engine cowling. When at high angles of attack, the strakes create a vortex and keep the boundary layer stuck to the wings. The 747–8 is also fitted with new wings which are way more aerodynamic than the ones on the 400s. This also improves the lift characteristics of the aircraft and helps to counter the effects of close-fitted engines.”

Lufthansa 747-8
The GEnx includes the world’s first composite fan case and fan blades for commercial jets. Photo: Getty Images

A powerful unit

Altogether, Boeing was excited to introduce the GEnx engine due to the advancements that it would bring. GE highlights that the engine offers up to 15% improved fuel efficiency and 15% less CO2 compared to the company’s CF6 engine. The firm emphasizes that the model encompasses the latest materials and design processes to reduce weight and improve performance.

The Boeing 747-8I conducted its first flight on March 20th, 2011 before entering service with Lufthansa on June 1st, 2012. Despite being the first commercial operation with the Intercontinental, the cargo variant, the 747-8F entered service with Cargolux on October 12th, 2011.

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Only three passenger airlines fly with the 747-8I. These operators are Air China, Korean Air, and Lufthansa. However, several cargo airlines enjoy hitting the skies with the 747-8F. Moreover, there is a future for the plane as the next presidential jet in the United States.

Overall, no matter what the variant is, the design of the 747 invokes sentimental feelings. The Queen of the Skies reminds us of a glorious era in aviation. Even though the type’s program will come to an end after five decades next year, at least it won’t be fully disappearing from our skies with the newer productions.

What are your thoughts about the Boeing 747-8? What do you make of the aircraft’s design compare with its predecessors? Let us know what you think of the plane in the comment section.