Re: 737NG (was: Seating Pitch)

Date:         17 May 98 00:43:03 
From:         amuir@twsu.campus.mci.netnospam (Andrew Muir)
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In article <airliners.1998.684@ohare.Chicago.COM>,
   niels@nospam.demon.co.uk (Niels Sampath) wrote:
>In article <faurecm-0203982300480001@blv-pm104-ip20.halcyon.com>
>           faurecm@halcyon.com "C. Marin Faure" writes:
>
>>In article <888762977snz@nospam.demon.co.uk>, niels@nospam.demon.co.uk
wrote:
>>
>>>European registered new generation 737s have had to
>>> have re-designed emergency exit doors installed to meet the regulations.
>>
>>All the New Generation 737s are being fitted (or retro-fitted) with the
>>new, faster-opening overwing emergency doors, and this door will be used
>>on 757s as well.

And probably 717.  I believe that Boeing has offered the technology to the
industry as a safety enhancement.  There is still some concern of inadvertant
deployment during take-off (this is the first time a passenger has been
leaning on a spring loaded door during take-off).  The fail safes are designed
in, but you never know.  But hey, its what the JAA wanted.

>IIRC it is a matter of record that Boeing initially resisted JAA
>pressure to design/install these new exits.  While I appreciate
>the sense of some aviation conservatism  I think that it can sometimes
>be open to question.

Not conservatism, but business thinking:  1) This is a derivative added to a
1965 or so certificate. 2) Is the design cost and weight penalty worth the
safety improvement?  I have seen video of the new door in action and it is
slick.

>For example: Why does the 737 still have the `707,727' cockpit/nose
>shape?

A former boss of mine told a story about working on the original 737 nose
design.  He said that they knew the 707/727 nose configuration was draggy and
that a better nose/windshield design would cut drag.  When program management
was approached on the issue the reply was they didn't expect to sell more than
150 of the things and that the design change wouldn't be worth the cost.  3000
built and 800+ ordered later . . .

As for why it wasn't changed on the NG, my speculation is that it gets harder
to certify a plane as a derivitive when it doesn't look the same.

>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.
>Whether that was the reason or if it was pure aerodynamics that dictated
>that   I am not sure,  but visibility was certainly improved.

My understanding (from my reading 20 years ago?) was when the decision was
made to go to a common cockpit arrangement for 757/767, it was easiest to
essentially graft on a 767 upper cab and work out the contours on the lower
section.  I never thought that the front end of a 757 looked "right".

>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.