Re: B747 technical questions

Date:         04 Aug 97 21:28:53 
From:         Trevor Fenn <>
Organization: Erol's Internet Services
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Steve Lacker wrote:
> Karl Swartz wrote:
> > >The Dash 80 also carried a 5th engine to support the 727 program.
> > >The JT8 was mounted just in front of the aft starbord cabin door ...
> >
> > Ok, that's how the JT8D was flight tested.
> Errrr.. Was it?!? I thought that the engine flown in that location was
> just a JT3D (or maybe even a J-57), mounted there by Boeing to
> investigate the effects of applying thrust at that location on the
> airframe. I could easily be wrong, but it seems to me that the
> ridiculous tailpipe (ever seen a picture of it? Its good for a laugh or
> two!) would have completely invalidated any realistic in-flight testing
> of a new powerplant like the JT8D. One couldn't even argue that it
> simulated the S-duct of a 727 since that is on the inlet side of things.

The engine tested on the aft fuselage of the Boeing 367-80 was in fact
the JT8D engine proposed to be fitted in that location on the 727. The
S shaped tail pipe that was fitted was there only to divert the hot
exhaust gas around the 367-80's horizontal stabilizer, not as any form
of test for the S Duct that would be required for the 727's number two
engine. At the same time this extra engine was fitted the -80 was also
modified to test the Krueger Flap/Slat/Triple Slotted Fowler Flap system
that would be fitted to the 727.

Trevor Fenn