Re: Rear engined aircraft. (727 DC9 MD80)

From:         drinkard@bcstec.ca.boeing.com (Terrell D. Drinkard)
Organization: Boeing Commercial Airplane Group
Date:         02 Dec 94 02:48:59 
References:   1
Followups:    1
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In article <airliners.1994.1723@ohare.chicago.com>,
ScottK1204 <scottk1204@aol.com> wrote:
>Someone posted a question on rec.aviation.misc recently that turned into
>quite a joke.  We still did not get an good answer.
>
>The writer wanted to know why the engines on 727, DC9, and MD80's seem to
>be canted nose up 1 or 2 degrees.
>
>The discussion turned strange when someone suggested that airliners have
>the ability to jettison engines by way of exposive bolts in the engine
>attachments.  There are quite a few of the folks who actually believe
>this.
>
>Can someone here give me an answer to the engine question so I can put
>this issue to rest.

No, airlines cannot jettison engines in flight.  In fact, it usually takes
a shift or two to change an engine, there are a lot of complex connections
between the airframe and the engine - electrical, hydraulic, pneumatic, and
structural.

The engines are canted up a degree or so to take into account the downwash
from the wing.  That is, when the wing generates lift, the flow is turned
downward behind the wing, which is where you find the engines on the 727,
DC-9, and MD80s.  Also the MD90, Fokker 70, Fokker 100, VC-10, Trident,
BAC 1-11, Canadair Regional Jet, and nearly every business jet ever built.
The engine is aligned with the local flow so that the air will go straight
into the diffuser and compressor with no lost energy, and minimal drag.

Terry


-- 
Terry
drinkard@bcstec.ca.boeing.com
"Anyone who thinks they can hold the company responsible for what I say has
more lawyers than sense."