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 January 2007
 
Boeing stretches 747-8I

By Sebastian Steinke

According to Boeing's latest plans, the impressive 76.4m overall length, that is, 5.6m longer than the 747-400, is no longer to be confined to the future 747-8F cargo aircraft, but will apply also to the 747-8 Intercontinental version for passengers which previously was to have been stretched only to 74.22m. Randy Baseler, Vice President Marketing at Boeing Commercial Airplanes in Seattle, explains the latest increase in length as follows. “We are in the middle of working out the details of the 747-8 and it has turned out that the new wing will be more efficient than we had originally assumed. This would have enabled us to raise the planned range of 8,000nm with 450 passengers and baggage. But our customers have told us they are happy with the original range and would prefer the greater efficiency to be used to increase the payload, that is, to accommodate more passengers.” By adding a 4.1m long additional, double-deck section of fuselage in front of the wings and an extra 1.5 m of single deck aft of the wing, Boeing will be able to increase the jumbo's passenger capacity to up to 479 passengers in a three-class configuration. This will bring the 747-8's capacity closer to that of the A380.

Boeing 747-8

For a long time Boeing quite categorically ruled out such a stretch, arguing that, the passenger jumbo would be too heavy and lose range if the already stretched 400 bulge were to be lengthened still further, to the length of the more slender 747-8 freighter aircraft with its short bulge. At the same time it was stated categorically that a 747-8I must match the range of the 787 if it was to be seamlessly interchangeable with that model on busy routes.

Dan Mooney, the new 747/747-8 Program Vice President appointed in July, explains the change of heart as follows. “After two series of wind tunnel tests, the third one is going on right now, we are confident that we can satisfy the market and customer requirements. In view of the recent hike in the price of fuel, we have not only increased the number of seats but we wanted at the same time to improve the costs per seat. It is true we have lost some range, around 300km, but we believe we have now arrived at a better compromise.” Nevertheless, he pointed out, a final decision on the stretch had not yet been taken, but a majority of the potential airline customers would prefer a longer version. In his former life as head of Product Development at Boeing Commercial Airplanes, programme manager Mooney had already been involved with the new jumbo variants.

Emirates, which is seeking a widebody aircraft for its long-haul Dubai-Los Angeles route, is the only airline to have expressed a definite interest in the previous, shorter 747-8i. Could Boeing not therefore offer both fuselage lengths in parallel? Dan Mooney: “Yes, we could in principle produce different fuselage lengths next to each other. After the first 747-8F we still have quite a few 747-400F's to build. And passenger and cargo versions are also different from each other. Two fuselages in the passenger version would be possible, if the market really wanted it. But at the moment we believe one length is better.”

Boeing expects to determine the final length of the 747-8I by next spring, irrespective of customer preferences. The company has already decided to step up expenditure on the design of the interior. Dan Mooney: “We decided that the performance improvements measured justify additional investment. The 747-8I will now get a completely new cabin interior in the style of the 787. This includes a new ceiling design, colour LED lighting and large, newly designed overhead bins.” In the preliminary 747-8I design, the now curved staircase to the upper deck was still located by the nose door in A380 style, but has since reverted to the position by Door 2 which has been standard since the 747-400. Due to the extended fuselage length, the cabin volume is also bigger. Hence the pressurised cabin equipment packs need to be more powerful. At the same time the cargo bay is also growing: in the stretched version, 16% more cargo can be carried on top of passengers' luggage.

So far there has been no interest in the new “Skyloft” area, passenger sleeper compartments in the upper deck of the rear fuselage, which are offered for the first time in the 747-8. Instead, the airlines surveyed apparently would prefer to have the Economy main galley moved to the rear upper deck near Door 3. Instead of the kitchen, there will then be more seats in the main deck, as a result of which the number of seats can be increased from the normal 465 to a maximum of 479. The remaining crown area is to be kept free of systems, especially pipework, so that Skylofts can then be accommodated in the space later on.

Assuming that its design is completed, as planned, in around six months in the Firm Configuration phase, the first 747-8I will be delivered about a year after the first 747-8F. This first air cargo aircraft is scheduled for delivery to Cargolux at the end of 2009. Whereas the future cargo aircraft, which carries 18 tonnes more payload than the 747-400F, already boasts an impressive 44 orders, the 747-8I has so far notched up only three sales as VIP aircraft; no airline has yet placed an order. However, in the long-term Boeing remains confident about the passenger version of the 747-8 as well, and is expecting it to account for two thirds of 747-8 sales compared with one third for the cargo function. Boeing predicts a total requirement of 999 aircraft in the size category “747 and above” over the next 20 years. The present list prices of the 747-8F lie between $279.5 million and $283.5 million, whereas the “long” 747-8 Intercontinental will be offered for between $272.5 million and $282.5. These price tags put the 747-8 only just below the A380 on price.

Why have the airlines so far been so hesitant about supporting the new version of the 747, the only aircraft to cover the entire market segment between the 777/A340 on the one hand and the approx. 100 seat greater A380 on the other? Dan Mooney explains: “We have only been offering the 747-8 for one year. But our key customers are currently primarily evaluating the 787 and the 777-200LR and need more time to decide where the 747-8 fits into their fleets. Again, we had not previously expressly guaranteed that any further versions of the 747 would actually be built.” Will the 747-8 profit from the latest A380 delivery delays? Mooney replies, “The A380 problems are not having any direct effect. Besides, it takes time for people to consider their responses. We prefer to concentrate on our own development programme and our objectives.”

Like the Boeing 777-300ER, 777-200LR and 777F, both versions of the 747-8 will be fitted exclusively with General Electric engines. With 295.5 kN of thrust, the GEnx-2B67 closely resembles the engine used in the Boeing 787. However, it has fewer engine stages and a narrower fan, while the jumbo's systems will continue to be based on bleed air. According to Boeing, the noise footprint of a 747-8 on take-off will be 30% below that of the lighter 747-400.

Both versions of the 747-8Iwill use an aerodynamically modified wing with improved, new profile, new trailing edge, raked wingtips and a modified and simplified flap system. In future the inboard flaps will have only two slots rather than three and the outboard flaps will have a single slot instead of two. The 747-8's roll spoilers will be electronically controlled by an FBW system which supplements the main controls, which will continue to be mechanical.

On 30 October the 747-8 cargo aircraft development programme attained an important milestone when it entered the Firm Configuration phase, i.e. its configuration was released. Dan Mooney is already looking forward to the work that now lies ahead of him: “2007 will be the year of detailed design work, while in 2008 we will start building parts and get production under way. We will start with the components with the longest lead soon.”

From FLUG REVUE 1/2007
 


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