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Aviation History
1982
1982 - 0710.PDF
Boeing tests the twins BOEING chief test pilot Lew Wallick has been getting some weekends off. This is unique in his experience of major certification efforts with Boeing's flight-test department. The company has put 767 testing on a five- day week for the past month, and that says more than 20 handouts ever could about its confidence in the pro gress of its two new products. Al though the 757 is on a seven-day week to begin with, Wallick expects the programme to respect Judaic and Christian ethics within three months or so. At the time of Flight's visit to Boeing Field, the 757 had flown twice. Pilots' caution dissuades Wallick from taking a newly flown aircraft like the 757 too far into the upturned por ridge bowl that passes for a sky in Seattle's late winter; the first few flights in the test schedule are timed entirely by the weather. His first impression, though, is that Boeing's goal of a common type rating for the two types will be attained. "After the flight-tests I'm very, very optimistic about it. I was reasonably confident before." On the first flight of the 757, Wallick felt "very com fortable" moving in and flying for mation on the 727 carrying the com pany's cameras. It will be another few weeks before high-speed, low-speed and manoeuvring stability checks on the 757 are complete, but in the ab- By BILL SWEETMAN Boeing Commercial's flight-test director Lew Wallick sits at the 767's controls sence of these results Wallick feels that the design office's efforts to make the two aircraft fly alike have been successful despite the difference in wing size and sweep, and the different lateral control systems (the 767 has an inboard high-speed aileron and the 757 does not). Wallick describes the 767 as "kind of like a large 737". It resembles the smaller twin in being a pleasant flying machine with relatively light control forces, easy to fly and manoeuvre by hand, and free from the feeling of great bulk and mass associated with a very large aeroplane like the 747. Although the 767's size and inertia are obviously noticeable compared with the far smaller 737, Wallick says that it feels "large but not huge". The cockpits of both new aircraft are virtually identical, and offer a marked improvement in visibility and noise level over earlier Boeings. Artificial pitch stability has been eliminated from the 767, much to everyone's relief. Both the Federal Aviation Administration and the Civil Aviation Authority have indicated that relationship of pitch control force to aircraft behaviour in the buffet region (high Mach and altitude) will meet certification standards now that Boeing has installed seven vortex generators on each wing. Wallick is "delighted that we ended up with a clean airplane". The pitch augmenta tion control system (Pacs), which Boeing designed as a precautionary measure, is "still back there on the shelf in case we need it for the 757", but this appears to be a remote possi bility—the smaller aircraft has a smaller wing, less sweep and a pro portionally longer tail arm, all of which should make for better natural pitch stability. Boeing has been and remains reticent about details of the of10" ,** • «« :.-i" efpr'
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