Date: 17 May 98 00:43:02 From: firstname.lastname@example.org (Stephen H. Westin) Organization: Program of Computer Graphics -- Cornell University References: 1 2 3 4 5 6
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email@example.com (Niels Sampath) writes: <snip> > For example: Why does the 737 still have the `707,727' cockpit/nose > shape? Because it would cost a lot to change it. > Looking at old magazines I have noticed that the original design > studies for the 757 (7N7) had the 727 nose/cockpit. Then , I have been > told, along came that PSA 727/Cessna collision over San Diego where > cockpit visibility (lack of) was deemed influential and it > was decided to improve the 757 cockpit windows to what it is today. Nope. The 757 nose was chosen, if I recall the contemporary announcement correctly, 1. To reduce drag. 2. To commonize the cockpit with the 767, which was being developed at the same time. Not only was there economy in sharing systems, but the 757/767 had a common type certification: any pilot qualified in one was also qualified in the other. Boeing thought of this as a selling point to airlines who wanted crew flexibility, but I'm not sure it worked out that way. 3. To increase cabin space. I think they got an extra row or so of seats out of it, without stretching the overall length. I think cockpit space also improved, as did the cockpit noise level. Similar things happened at the tail; the 757 was originally destined to carry over the 727 tail, with the center hole plugged. The new tail reduced drag, while reducing the overall length of the aircraft (important for ground handling) and adding a row or two of seats in the cabin. The 757 was, of course, a 727 replacement. It originally was to be just a '27 with a new wing, two new engines mounted on the wing, and new flight systems. It kept changing during development. I think AA had a scheme to re-engine their 727s as a cut-rate 757 substitute, but Boeing talked 'em out of it: the new wing and flight systems were a lot of the improvement in the new airplane. > Whether that was the reason or if it was pure aerodynamics that dictated > that I am not sure, but visibility was certainly improved. > Nevertheless no improvement was made to the newer 737s even though > I -did- see one early design study of the 737-300 that had a 757 > nose/cockpit! With the newer-still 737NGs, again, no improvement was made. > Conservatism rules. Not a bad thing, really; changing the whole nose would require lots of certification effort, even beyond the engineering expense. And any change has the chance to introduce some unsuspected problem. Which, I suppose, is the reason behind the certification hassles. -- -Stephen H. Westin Any information or opinions in this message are mine: they do not represent the position of Cornell University or any of its sponsors.