Boeing 747-100SR

The 747-100SR is the 747 built backwards. Every other variant was pushed towards more range; the SR was pushed towards more cycles. Japanese domestic routes were short, extraordinarily busy, and flown many times a day - so what those airlines needed was not an aircraft that could cross an ocean, but one that could take off and land again, and again, for decades.

Boeing's answer was to cut fuel capacity by about 20 percent and put the weight saved into structure.

What was changed

• Extra structural reinforcement at the wings, fuselage and landing gear, to absorb the fatigue loading of far more takeoff and landing cycles than a long-haul 747 sees.
• Fuel capacity reduced by roughly 20 percent.
• Economy seating increased sharply - up to 498 in early aircraft and over 550 in later ones.

The -100SR entered service with Japan Air Lines on 7 October 1973. Twenty-nine SR-family aircraft were built in total: seven 747-100SRs, twenty 747-100BSRs on the strengthened -100B structure, and two 747-100BSR SUDs.

The stretched upper deck came from here

Those last two matter out of all proportion to their number. The SUD - stretched upper deck - was first delivered on Japanese SR aircraft, extending the upper deck 23 ft 4 in aft and turning the hump from a lounge into a cabin.

Boeing later made it the defining feature of the 747-300, and it stayed on every 747 built afterwards. The most recognisable change in the aircraft's history began as a modification for domestic Japanese flying.

Specifications

Passengers, single class	Up to 550
Engines	Four Pratt & Whitney JT9D-7A (205.3 kN) or General Electric CF6-45A2 (202.8 kN)
Empty weight	164,510 kg
Max zero-fuel weight	219,950 kg
Fuel	183,360 kg
Max payload	57,060 kg
Max takeoff weight	272,100 kg
Max landing weight	255,800 kg

How they finished

All Nippon Airways flew 747SRs on domestic routes with 455 or 456 seats and retired the last on 10 March 2006. Japan Airlines operated the 747-100B/SR/SUD with 563 seats and retired them in late 2006.

The concept did not die with them. Boeing built it again a generation later as the 747-400D, a domestic 747 with the winglets deleted because on a one-hour sector they never repay their own weight - and a 747-300SR filled the gap in between.

An extraordinary fact about these aircraft: a 747SR could accumulate more than 30,000 flight cycles in its life, against a few thousand for a long-haul 747 of the same age. They were the hardest-worked jumbo jets ever flown.