Those swinging engine pods!

From:         Don Webster <71352.340@CompuServe.COM>
Date:         30 Mar 94 00:06:40 PST
References:   1 2 3
Next article
View raw article
  or MIME structure

I have not been reading this line until Brad's message, so I may 
repeat some of what has been said, however regarding the following:

>The question is, if an engine falls off a plane during flight, is that
>an automatic downer for the aircraft, or are there certain admissible
>scenarios?  If an outboard engine falls off a 747 in flight, can the
>aircraft recover?

Engine mounts are made a weak link on purpose specifically for the
survivability of the airplane should and engine seize.  I flew Navy
A-3s for many years which had wing mounted engines.  Not often, but
occasionally one of the old J-57 engines would seize and spin it off
of the mounts.  Usually it would be held by the cowling and drop a
few inches.  It was exciting, but the plane made it home.  I recall
one engine being lofted in a verticle loft manuver back when the A-3
was the Navy's long range nuclear bomber. The plane flew home, although
I'm sure it was worth a round of beers at happy hour for the sheepish
crew.  My captain on a flight just two days ago described an identical
incident which happened to him on a loft manuver of a B47; he was 
disgusted that the engine missed the target.

Regarding the direction of movement, in almost any turbulence one can
look out at a 747 engine and see it flexing in a twisting motion, which
I'm sure is a gyroscopic response to the up and down movement of the
wing.  Allowing the engine to flex reduces the gyroscopic forces that
would otherwise have to be resisted, or rather, allows those foces to
be damped over a longer period of time.

Don Webster