Re: 747 hump

Date:         16 Sep 97 02:35:25 
From:         jf mezei <"[non-spam]jfmezei">
Organization: VTL
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Mark E. Ingram wrote:
> An _AvWeek article of three or four years ago stated flatly that Boeing
> aerodynamicists were totally surprised when the longer hump of the first
> "extended upper deck" 747 (the -300) caused a *decrease* in drag over the
> original design.  Can anyone comment on (or verify) this?

(speculation) If the hump of the SUD "fades" over a longer distance, and
the hump of the -200 ends more abruptly, I would *assume* that airflow
disruptions would be lessened. I would also speculate that on the SUD,
there is a long enough section of "smooth" fuselage where the
disruptions caused at the front of the hump have time to smooth out a
bit before the disrubtions caused by the end of the hump occur. Is this
a fair appraisal ? Or totally out of wack ?

But if the hump actually reduces drag, how come other Boeing planes
which were designed afterwards (767,777) don't have a hump too ?