Re: 737NG (was: Seating Pitch)

Date:         17 May 98 00:43:02 
From:         westin*nospam@graphics.cornell.edu (Stephen H. Westin)
Organization: Program of Computer Graphics -- Cornell University
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niels@nospam.demon.co.uk (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.