With June set for firming the configuration of the 787-9, Boeing is taking major strides to incorporate what it has learned on testing the 787-8 in the air and on the ground to optimize the aircraft. The first 787-9 was initially intended to be Airplane 88, which later became Airplane 109 and now stands at Airplane 139 (ZB001). The first 787-9 will be delivered to Air New Zealand at the end of 2013.
The task ahead is an engineer’s dream (or nightmare): Stretch an airframe 20ft, add about 40 seats, make it fly 8,000 to 8,500 nm – farther than its predecessor – all while keeping the wing the same span, and having having 100gal less fuel to work with, all while removing potentially thousands of pounds of excess weight from the original -8 design.
The stretch, which comes entirely in two 120in, 5-frame additions to the 43 section (built by Kawasaki) and the 46 section (built by Alenia), will come through the production system through center fuselage integration at Boeing Charleston, which was sized for the larger aircraft.
The 787-8 and -9 wing has been a subject of great debate inside Boeing for years now, as the -9 wing grew three times to 207ft 11in, then came back to a common planform as the -8 with a 197ft 3in wingspan last Spring as early static tests and the -18 wing break test showed the strength of the wing box (side-of-body not withstanding). Additionally, the reduced span was set set to save an estimated 4000lbs, which would have cost more range than the increase in aerodynamic efficiency would have yielded.
With static airframe (ZY997) testing heading toward ultimate load, the design of the side-of-body reinforcement will be put through its paces, allowing Boeing to resize the fittings if necessary, which have added a notable amount of weight to the aircraft to ensure their strength, say those close to the aircraft. Additionally, the flight loads survey that will be conducted by ZA004 will help calibrate finite element methods used to size the 787-9.
Program engineers also say that the one-piece barrel structures have survived loads far beyond expectations, and well in excess of certification requirements. While a marketing victory of sorts, those same engineers see that kind of strength in the -8 as a sign of an over-designed structure. The more Boeing learns about the -8 structure, the more optimization can take place for the -9.
Major changes – many obstructed from public view – will be coming on the systems level for -9. The Airbus Dossier of October 2008 – and its conclusion – provide some indication of the changes coming, but more than a year later, program sources say that the guts of the -9 are “significantly different” in some areas to the -8. One known area is an increase in the APU power output from 225 KVA on the -8 to 250 KVA on the -9, along with a revised cargo environmental control system.
The landing gear, for example will be larger than that of the -8 with larger main trucks and wheels, tires and brakes. As a result, the wheel well pressure deck will be raised and the structural architecture revised to accommodate the larger landing gear.
For Rolls-Royce, the technology developed for the Trent 1000 Package B engines set to be tested first on ZA004 later this year, will be a big driver for the entry into service fuel burn expectations of the 787. Even beyond that, Rolls-Royce is aiming to have an additional 1% improvement even beyond the Package B EIS spec, not to mention whatever Trent XWB designs are fed back into the 1000.
Not to mention, we’ll finally find out what happened to that missing window!
This post was originally published to the internet between 2007 and 2012. Links, images, and embedded media from that era may no longer function as intended.
This post originally appeared at Flightglobal.com from 2007 to 2012.
