Early development

The longer-range, higher weight "747B" - which entered service with more powerful JT9D engines in early 1972 as the -200B - addressed the capability deficiencies of the original Jumbo, delivering the airfield performance originally specified.

From start, a freighter version was in the plan as part of the 747's weight/performance growth path. At the time of the 747's conception, the all-cargo role was seen as the most viable long-term future for the airframe given the expected arrival of supersonic transports. This was largely why the cockpit was installed above the fuselage, enabling the airframe design to be easily adapted for full-deck cargo and nose-loading.

The 747-200F arrived months after the -200 passenger model, and the freighter versions were an important supplement to the aircraft's sales fortunes. All-cargo 747s accounted for 239 of the 1,418 aircraft delivered before the production switch to the -8 family, and many more ex-passenger aircraft have spent their later years in the freight role.

CARGO TO THE FORE

Analysis by Flightglobal Insight from the ACAS database shows that throughout the 747's 40 years so far, the commercial in-service fleet peaked at 994 units in 1999. However, by then the passenger fleet was already in decline as the number of cargo variants flying began to come to the fore (over 200 in service - see graph). The passenger fleet reached its peak in the 1994-98 period, at just over 800 units.

Today, the active passenger 747 fleet has declined to fewer than 500 units, while the freighter total stands at 280 aircraft (having fallen from a peak of 334 in 2007), representing more than one-third of the entire fleet.

© Flightglobal/Tim Bicheno-Brown

As Boeing sought to maximise the performance and appeal of its flagship, it brought the other two players in the engine market on board to power the ever-improving -200 models - General Electric with its CF6, and Rolls-Royce with the RB211-524.

After the arrival of the higher-weight and freight variants, Boeing came up with a bizarre Jumbo development that would ultimately prove relatively unpopular, the short-fuselage 747 Special Performance. Offering what for the time (1976) was ultra-long-range capability, the SP was partly created to keep Pan Am from buying one of the smaller widebodies - the Lockheed TriStar or McDonnell Douglas DC-10. The SP's unique capabilities - and looks - did not prove hugely popular, with just 45 aircraft sold.

Introduction of higher-capacity variants was another long-term plan for the airframe. The upper deck area behind the cockpit, which had initially been used for in-flight recreation by premium passengers, had soon been adapted to serve as a proper passenger cabin, with additional windows and a second emergency exit to give a slight boost in capacity.

© Boeing

Boeing had also been quick to develop a high-density "747 Super Airbus" derivative of the baseline aircraft for Japanese domestic routes. Designated the 747 SR (Short Range) at service entry in 1973, Japan Air Lines configured the aircraft with what then was an unprecedented capacity of 498 seats. Later "Domestic" versions of the 747-400 aimed at the same market would seat almost 570.