Re: 747 hump

Date:         28 Sep 97 20:59:08 
From:         drela@mit.edu (Mark Drela)
Organization: Massachvsetts Institvte of Technology
References:   1 2 3 4 5
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In article <airliners.1997.2285@ohare.Chicago.COM>, Marc Schaeffer <marcmsc@geocities.com> writes:
> Steve Lacker wrote:
> > Marc Schaeffer wrote:
> > > How can a fuselage contribute to the lift ????
> >
> > The same way a wing does! higher air velocity on the upper surface
> > results in a lower pressure on the top surface than on the lower one.
> > Thats exactly how "lifting body" aircraft (thus far mainly experimental)
> > operate.
>
> Does *any* of todays commercial a/c have such a fuselage ??
> If yes, what amount of total lift (%) does it provide ??
>
> > Now, I don't know whether or not the 747 hump truly produces lift... but
> > a lifting fuselage is possible.
>
> Take a banana as fuselage and you got it  :-)

Not necessary.

A straight fuselage will naturally carry some lift since the pressure
difference above/below the wing gets partially carried over onto the
fuselage.  The wing's pressure field cannot stop dead at the wing root!

The lift carried by the fuselage is considerable.  For a mid wing
it is comparable to the lift you would have on a carry-through
section of the wing.  For this reason, the reference wing area
defined for a jetliner often includes this imaginary "interior"
wing area.

  Mark Drela                          First Law of Aviation:
  MIT Aero & Astro          "Takeoff is optional, landing is compulsory"