Re: Wing vs. tail-mounted engines?

Date:         27 Mar 2001 16:05:17 
From:         leodmo@earthlink.net
Organization: EarthLink Inc. -- http://www.EarthLink.net
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"Wolfgang Keller" <w_keller@gmx.de> wrote in message

> What are the actual design tradeoffs today and how did the situation
> evolve over the past decades to favor wing-mounted engines that much? What
> would be the impact of, for example, drastically increased fuel prices
> and/or significantly more strict noise regulations (=> engines with bypass
> ratio >>10)?

I haven't read any articles addressing the issues of weight, balance, and
aerodynamics.

However, safety might be a major reason for "below the wing" mounted
engines. When an engine is in serious trouble in the rear of the AC, it can
take out the other engines or critical hydraulic systems. (DC10 at Sioux
City, IO)

If an engine is mounted in a wing, then the engine can damage the wing or
fuel tanks.

When mounted below the wing, the engine parts (catastropic failures) have a
smaller probability of hitting critical wing parts or the fuel tanks. Also,
external mount allows the engine to actualy depart the AC leaving the AC a
chance to fly.

Although the following paragraph may not relate to modern jet design, you
may find it interesting.

Remember the old Boeing Stratocrusers (passenger form of the B29-B50). An
engine could (and did) fail in such a way that the entire engine would twist
out of the wing and depart the AC. This added so much drag to the AC that it
could not fly with three engines at full power. At least 4 accidents were
directly attributed to the complete physical loss of the engine and there
were several other near misses where the pilots could make a powered glide
to an airstrip.

Dennis