747-8

The Boeing 747-8 was the fourth and final generation of the 747: a longer fuselage, an entirely new wing, and four GEnx-2B engines. With a maximum takeoff weight of 987,000 lb (447,700 kg) it is the heaviest aircraft, commercial or military, ever manufactured in the United States.

Boeing announced the 747 Advanced as the “747-8” on 14 November 2005. The first 747-8 Freighter went to Cargolux in October 2011 and the first Intercontinental to Lufthansa in May 2012. 155 were built — 107 freighters and 48 passenger aircraft — and the very last 747, a Freighter for Atlas Air, was delivered on 31 January 2023, closing a production run of 1,574 aircraft.

Along with the 747SP, it is one of only two 747 variants whose fuselage length was ever changed from the original — and the only one that was ever lengthened.

The stretch

The 747-8 is 18 ft 3 in (5.6 m) longer than the 747-400, at 250 ft 2½ in (76.26 m) overall. The extra length comes from two fuselage plugs: 13 ft 4 in ahead of the wing and 5 ft behind it.

That made it the longest passenger airliner in the world on entry into service, exceeding the Airbus A340-600 by about 3.6 ft.

The wing

The wing was the largest engineering change, and it was a complete redesign rather than a modification.

Boeing kept the sweep and basic structure to contain cost, but made the wing thicker and deeper with the aerodynamics recalculated from scratch — a different pressure distribution and different bending moments. Fuel capacity rose to 63,034 US gal (238,610 l) on the passenger version. (Programme material from 2005-08 quoted a planned 64,225 US gal; the as-built figure is lower.)

Other changes:

• Single-slotted outboard flaps and double-slotted inboard flaps.
• Raked wingtips replacing the -400’s upright winglets — the same solution used on the 777-200LR, 777-300ER, 767-400ER and 787. They reduce the wingtip vortices at the lateral edges of the wing, cutting wake turbulence and drag.
• Some carbon fibre reinforced plastic in the airframe to save weight, though structural changes overall were evolutionary rather than revolutionary against the -400.

One neat consequence: because the redesigned wing carried so much more fuel, Boeing did not need to rework the horizontal tail to take auxiliary tanks — a saving that came free with the new wing. The vertical tail was raised slightly, to 64 ft 2 in (19.6 m).

There is a detailed page on the 747-8 wing in the reference section.

The engines

The General Electric GEnx — one of the two powerplants offered on the 787 — was the only engine ever available on the 747-8. The 747 version was adapted to provide bleed air for conventional aircraft systems, and given a smaller fan diameter to fit under the 747 wing.

An exclusivity agreement between GE and Boeing meant no other manufacturer’s engine could be fitted for at least ten years. For an aircraft whose predecessor’s success rested substantially on offering three engine choices, that was a striking reversal — and it removed one of the reasons airlines had historically chosen the 747.

A difficult programme

The 747-8 did not have an easy birth. Production of the first Freighter began at Everett in early August 2008. On 14 November 2008 Boeing announced a delay, citing limited availability of engineering resources inside the company, design changes, and a factory workers’ strike. First Freighter delivery slipped from late 2009 to the third quarter of 2010; the Intercontinental slipped from late 2010 to the second quarter of 2011.

By February 2009 only one airline customer — Lufthansa — had ordered the passenger version, and Boeing publicly reassessed the project. Chief executive Jim McNerney said continuation was not a foregone conclusion.

The programme continued, but that early warning proved accurate: the passenger version never found a broad market, and the freighter carried the aircraft to the end.

Against the A380

The 747-8 was pitched directly against the Airbus A380 on long-haul routes, and both were shaped by the same bet — that hub-to-hub traffic would keep growing and airlines would want ever-larger aircraft.

The bet was wrong for both. Airlines moved to smaller, more efficient twins flying point-to-point, and neither very large aircraft sold as hoped. A380 production ended in 2021; the 747 followed in 2023.

The two versions

• The 747-8 Intercontinental — the passenger aircraft. 48 built.
• The 747-8 Freighter — the cargo aircraft, which flew first and sold better. 107 built.

For a fuller treatment of the aircraft, see Everything about the Boeing 747-8.