Re: DC10/MD11 engine #2 redundant?

From:         Jim Messina <sky@neosoft.com>
Organization: NeoSoft, Inc.
Date:         22 Jun 96 18:30:35 
References:   1
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On 10 Jun 1996 Thomas@.MISSING-HOST-NAME. wrote:

> I have a question regarding the tail engine of a DC10/MD11.
>
> I've heard a rumour that the tail engine (#2) is mainly used during
> takeoff in order for the aircraft to take a larger payload
> at takeoff compared to a two engined widebody. En route #2 is
> throttled back to a minimum level leaving #1 and #3 running at
> full throttle.

I have never even heard of such a thing!

> #2 was also supposed to point in an angle slightly more
> towards the ground in order to support takeoff with large payloads.

Never heard that expressed either. The engine appears to be angled as you
describe and simple vector analysis would suggest there is some small
component of "lift". One engine has approximately 50,000# of thrust at
takeoff. Probably doesn't amount to much, IMHO.

One thing the angled #2 engine probably does do, is oppose somewhat the
destabilizing effects of power changes on the wing engines. One can
hand-fly the airplane very nicely with the Autothrottles on.

Running the Autothrottles on while hand-flying an airplane such as the
Boeing 737 -300 with it's powerful under-wing engines can be a struggle.

Bluecoat Digest mail list maintainer- Jim Messina
http://www.neosoft.com/~sky (Bluecoat Web links)