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BOEING EXPANDS 777, 767 AND 757 FAMILIES
by Norbert BurgnerIn mid-September, Boeing presented its new mega-twin 777-300 for the first time to the public. Only four weeks later, on 16 October at 10:27 local time Seattle, the largest "Triple Seven" yet took of for its first flight, starting into a seven-months certification program. Certification is scheduled for the end of May 1998. Until then, a total of six aircraft (two or three with Rolls-Royce engines, two with Pratt & Whitney engines, and, possibly, one with General Electric turbofans) will accomplish the test program. The GE version still has a question mark on it due to a lack of customer interest.
Boeing lists the 777-300 for a price between 138 and 170 million US dollars, making the stretched version approximately $18 million more expensive than the basic -200. But, the customer also gets "more" aircraft: With a length of 73,80 meters, the big 777 is 10,10 meters longer than the -200. This was accomplished by integrating two additional fuselage sections. Ten frames with a section length of 5,33 meters were added to the forward fuselage, and a nine-frame section (4,80 meters) was added aft of the wings.
The modifications increased the passenger capacity by approximately 20 percent up to 550 (all-economy). This puts the 777-300 in the region of the 747-400 that offers a maximum of 568 passengers. In one aspect, the new twin has even surpassed the Jumbo Jet: The -300 is not only bigger than its sister model but, it is also 3,20 meters longer than the 747-400, making it the longest airliner in the world. Still, with a maximum take-off weight of almost 400 tons and a range of up to 13340 kilometers, the Jumbo Jet remains the world's largest airliner.
Boeing states a take-off weight of just under 300 tons for the new 777. The aircraft has the same fuel capacity (171160 liters) as the 777-200IGW, giving the -300 a non-stop range of 10556 kilometers.
While the 777-300 has almost the same seating capacity as the 747, it uses approximately one third less fuel than the Jumbo, supposedly generating up to 40 percent less maintenance costs. According to Boeing, the -300 has the potential to save 30 percent of the direct operating costs at the bottom line.
Still, it was not the goal to generate an in-house competition but, to expand their own product range against the competition, first of all against the archrival from Toulouse.
Boeing says that already the 777 basic version, on a typical 7400 nm mission and laid out in a three-class configuration, offers up to 16 percent better relative seat-mile costs than the A340. Comparing the Airbus with the 777-300 and its high passenger capacity (plus 43 percent in three classes) makes the Boeing airliner look even better. However, the comparison is rather theoretical since there is a direct dependence between seat mile costs and the potential seat load factor.
Nevertheless, even if Airbus Industrie would try to close the gap to the 747 by developing further variants of the A340, Boeing, according to its own statements, is well prepared. "Our 777-300 already offers 13 percent more room than any possible A340 version. Should a customer want more range, he will buy a 747. Should he require more range, our 777-200X and 777-300X are the answers to the projected Airbus A340-500 and -600 versions.
The two -X versions of the Triple Seven are basically extended-range variants of the basic -200 and of the new -300. In order to make room for the extra fuel, Boeing has made a virtue of necessity: The higher design weight of the new models requires more lift. It is planned to extend the wingspan of today's 777 wings by a good four meters from 60,90 m to 64,90 m. The extra space in the wingtips is going to be used for the extra tanks (approximately 4120 liters on each side), increasing the fuel capacity of the -300X to 179300 liters. In order to realize the ultra-long range of the -200X (16158 km), further fuel tanks (two times 8650 liters) will be integrated in the aft fuselage, increasing the aircraft's fuel capacity to 196600 liters.
The gear will have to be modified to cope with the higher weights. The -200X will be fitted with the already strengthened gear from the -300. The undercarriage will be further modified with larger nose wheels and tires. Further structural reinforcements are planned for the fuselage, the wings, and the empenage.
The X models will be powered by uprated turbofans from Rolls-Royce, Pratt & Whitney and General Electric. With a thrust of 102000 lbs, the Trent 8102, PW4098 and GE90-102B1 will be approximately 30 percent more powerful than the engines powering the -200 basic version. The final assembly of the -200X could start in August of 1999, the -300X following four months later.
Around the same time frame, Boeing plans to celebrate the roll-out of the new 767-400ER. The -400 is designed to increase the sales of Boeing's mid-size family, not only in the domestic market but, especially on the transatlantic race tracks.
As compared to the 767-300, the -400 is stretched by 6,43 meters, offering a capacity for 245 passengers in a three-class configuration. This is approximately 15 percent more than the so far largest version, the -300ER, offers. From Boeing's point of view, the potential 5-percent advantage in relative operating costs, as compared to the Airbus A330-200, is much more important.
While the long-range version of Airbus' wide-body twin has a longer range (11945 km as compared to 10460 km of the 767-400ER), this range is rarely used to the maximum extent on the typical route profiles. Furthermore, Boeing states that the compromise between reducing the seating capacity in favor of a longer range increases the seat-mile costs of the A330. Another weak point of the Airbus twin, according to Boeing, is that it weighs 26 tons too much, generating a further cost disadvantage in respect to airway and landing fees.
As compared to Boeing's own product family, the 767-400ER with a maximum take-off mass of 204 tons is clearly the heaviest of the 767 versions (18 tons more weight than the -300ER), resulting from an increase in passenger capacity, as well as from structural upgrades. The new 767 will be fitted with an additional 3,40-meter fuselage section forward of the wings, and another 3-meter section aft of the wings. The wings will be reinforced in the center wing box area and will be lengthened by 2,175 meters on each side, increasing the wingspan to 51,92 meters. Also, winglets (2,35 meters) will be fitted at the wingtips.
The landing gear will be extended by another 38,1 centimeters and will be moved out sideways approximately 23 centimeters. Reportedly, wheels and brakes from the 777 will be used.
All other modifications are on the system side. The cockpit display technology and the avionics suite will be adapted to the future demands of Boeing's family commonality.
Because of the avionics and because of the higher power needed to run the air-conditioning and in-flight entertainment system, the -400 will be equipped with a more powerful electric supply (increased from 90 to 120 kW).
There will be no changes to the engine options, keeping the PW4000, CF6, and RB211 which are powering the -300ER. Still, Boeing asked for a thrust increase of three percent (up to 276 kN). Pratt & Whitney and General Electric can fulfill the task by increasing the turbine temperature. Rolls-Royce has set itself more restricting thermal limits by choosing a smaller fan diameter for the engine, giving the RB211 a disadvantage as compared to the other two suppliers.
Following its debut in August of 1999, the -400ER will supposedly enter the market in May of 2000. The motto "market advantage through cost efficiency", which was applied already to the Triple Seven program, will also apply to the new "Six Seven", says 767 chief engineer Hank Queen.
Daniel Mooney, chief engineer of the new 757-300 program, likes to use the same phrase for his product: 17 per cent more range (6500 kilometers), 20 percent more passengers, ten percent lower seat mile costs, and 48 percent more payload are the cornerstones of the new 757-300, as compared to the smaller sister model -200 and, looking at the products from Toulouse, 14 percent lower seat mile cost than the competing A321. However, this is not difficult since the 757-300 has a 44,5 percent higher seating capacity.
Stretched by 4,06 meters forward of the wings and 3,05 meters aft, the new 757 has a length of 54,40 meters and has a seating capacity for up to 289 passengers, such being the world's largest narrow-body airliner.
In conjunction with the other necessary structural reinforcements (mainly the wing that has thicker spars, planks and stringers), the new 757 has a maximum take-off weight of 122470 kg, such being 18 tons heavier than the basic 757-200 version.
The final assembly started at the beginning of September (the -300 is being assembled on the same line as the -200 due to costs). The roll-out of the airliner, which is listed for a price between 68 and 75 million dollars, is scheduled for May of 1998. First deliveries to launch customer Condor are supposed to begin in January of 1999.
With only 27 months from the first design drawings until the first delivery, the new 757-300 will brake the record for the fastest development running time in the history of Boeing aircraft.
Asked for the potential of further 757 derivatives, such as a long-range version from the -200, Mooney answers cautiously: "The profitable business for such an aircraft, for example on the routes from Frankfurt to the Caribbean, is beyond the range that can be realized with this aircraft. Also, the necessary fuel capacity would reduce the seating capacity so much that the seat mile costs would go up extremely, making this business case unrealistic. A more realistic option would be to give the new 757-300 a range of 9200 kilometers. Still, even in this case we must consider the remaining payload."
One may also ask the question of where the limit is up to which a manufacturer like Boeing has to react to each possible customer demand.
From page 34 of FLUG REVUE 1/98
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