Et notamment pour le -8 les poids objectifs ratés pour le Ln90 ... vu que Ln70 à Ln90 reste à 4 t au dessus d'un objectif qu'on ne connait pas...
Quel est cet objectif ? celui de la configuration ferme de septembre 2005 ? (95.5 t pour le 787-8 MTOW 215.9) ou une autre ?
Idem pour le 787-9 quelle est la réf, celle de la config ferme en 2005 (102.9 t pour 244.9 t de Mtow) ou celle d'une itération plus tardive ?
Ce qui est sûr c'est que l'objectif pour ZA001 mentionné par Aspire aviation est cohérent avec le poids à vide du 787-8 à l'étape ADS K ad (avril 2008) avec un MTOW de 219.5t. L'étape suivante en août 2008 avec le MTOW définitif ce poids à vide et de 101.2 t. Est ce celui là l'objectif pour le 787-8. En tout cas c'est mon hypothèse de travail.
Pour le 787-9 c'est la même chose ? quelle référence, dans le fameux doc d'airbus on s'arrête en avril 2008 avec un MTOW différent de celui retenu finalement. Le dernière trace est à 108.4 t avec un MTOW de 247.2, et il manque 3.6 t par rapport à l'objectif final. Est-ce que ce gain de MTOW peut être gratuit ? En tout cas il doit être peu coûteux car le MZFW n'augmente pas.
Meanwhile, reducing the 787-8′s weight is the next biggest challenge to Boeing as it brings the 787-9 to the marketplace in early 2014.
Aspire Aviation has previously reported LN1 weighed in at 109.9 tonnes (242,500lbs) in manufacturer’s empty weight (MEW), 9.75t (21,500lbs) over the target of 221,000lbs whereas LN7 and LN20 are 6.1t (13,500lbs) and 3.99t (8,800lbs) overweight, respectively.
However, Aspire Aviation has learnt that a 787 customer due to receive a production example between LN66 and LN90, the first clean 787 with no travelled work and the first 787 planned to meet the aircraft’s original manufacturer’s empty weight (MEW) and airline-specific operating empty weight (OEW) targets, respectively, is still 4 tonnes overweight, thus rendering meeting the LN90 weight targets as “unachievable”, multiple sources at Boeing say.
The same sources attributed the likely miss in meeting the LN90 weight targets to a lack of abundant 787-9 parts, as the -8 parts are “over-engineered” and “well over-designed”.
The weight reduction programme on the 787-9 stretch variant is going on “smoothly”, with ZB001 or LN126, the first 787-9 example to be produced is to meet its manufacturer’s empty weight (MEW) along with the first batch of 787-9s, with the MEW of later-built 787-9s expected to be 2% lighter, Aspire Aviation can exclusively reveal.
“We have a very robust baseline and we’ve learned a lot of lessons. We’re ecstatic with where we are with weight. When we hit firm configuration, we locked in on a number and we’ve just come down on that. As in any new aircraft design, at every turn there’s a risk and an opportunity. On the -8, after firm configuration the weight grew, but the -9 is a more stable design that builds on the experience of the -8 in terms of structural static and fatigue,” Boeing 787 vice president (VP) and chief project engineer (CPE) Mike Sinnett told Aviation Week.
“We are getting cleaner aircraft. When we designed it with an all-composite wing and fuselage, we were conservative. Then, as we started looking at weight-reduction changes and we rolled in things like the improved wingbox and the results of full-scale fatigue and static tests, this allowed us to be less conservative.
“[As a result], we’re seeing some level of surprise that it is performing as well as it is. You always want to talk yourself into thinking that something is not quite right, but its performance is basically spot on. There was a misconception in part because of the weight challenges early on. People expected the initial aircraft would be heavy, and maybe they are by a little bit, but even the early aircraft are performing to specification,” Sinnett commented.
The 787-9 has hit the 85% engineering drawing release milestone, the Aviation Week report says.
“From a production standpoint, all the major structural pieces are in initial build. In a lot of cases, we’re early. It’s a significantly different spot we’re in than we were with the -8,” Sinnett said.
The 787-9 is a 6.09m (20ft) stretch of the -8 with a range of 8,050nm (nautical miles) while carrying 280 passengers in a standard 3-class configuration. It features a swathe of weight improvement packages from Spirit AeroSystems’ one-piece cockpit window frame that will eliminate around 200 fasteners and reduce the cockpit structure’s weight by 100lbs, to the elimination of side-of-body modification which saves 363kg (800lbs) in weight.
In addition, improved engines such as the 76,000lbs Rolls-Royce Trent 1000 TEN (Thrust Effciency New Technology) and the 75,000lbs General Electric GEnx-1B PIP 2 will further improve the economics of the 787-9, along with the passive hybrid laminar flow control (HLFC) which the aforementioned Aviation Week report says is still planned to be included on the stretch variant.
The Rolls-Royce Trent 1000 Package A engine missed its original engine specific fuel consumption (SFC) by 4.3% and the Package B will exceed the SFC target by 2% and the Trent 1000-TEN engine will be around 0-1% better than the original SFC target. In comparison, the General Electric GEnx-1B engine has missed its original SFC target by 2.7%, with performance improvement packages PIP1 and PIP2 clawing back 1.6% and another 1% of fuel efficiency, respectively.
Image Courtesy of Boeing
Widebody strategy
While the risk profile of the 787 is hopefully declining at last and brings shareholders a relief with a largely stable research and development (R&D) spending, the relief may well be short-lived as Boeing faces a set of challenges in formulating its widebody strategy that is unique to the Chicago-based plane-maker as Airbus is mounting a challenge to both the 777 and 787 at the same time with its A350 XWB family.
Boeing’s future widebody strategy centres around the double-stretched 787-10X and the revamped 777X aircraft, with key decisions yet to be made on how much and to what extent the makeover should be to the highly successful long-haul 777 family which sold 200 examples last year.
The 323-seat 787-10X is expected to be launched imminently with an authority to offer (ATO) within October, Aspire Aviation‘s multiple sources confirmed the news which had firstly been reported by Leeham News. The 787-10X will have a range of 6,750nm when equipped with the Rolls-Royce Trent 1000-TEN engine or 6,700nm with the General Electric GEnx-1B PIP2 engine. It will feature the same maximum take-off weight (MTOW) as the 787-9 at 250.8t (553,000lbs), a maximum landing weight (MLW) of 201.8t (445,000lbs) and a maximum zero fuel weight (MZFW) of 192.8t (425,000lbs).
The 787-10X will be 5.49m (18ft) longer than the -9, with a 4-frame and 5-frame stretch in the forward and aft fuselages, respectively and will burn 25% lower less fuel than an A330-300, as well as a 10% and 5% lower operating cost than the A350-900 and -1000, respectively.
Accueil
Portail
Galerie
S'enregistrer
Connexion
par Poncho (Admin) Lun 1 Oct 2012 - 9:51
-------------
