Dave S wrote:
Scuse me.. I'm not a multi driver... let alone a 747 pilot...

but if I lost 25 percent of my power I think that I would notice some
performance loss...



I am a multi pilot but I've never flown anything bigger than a cabin class twin.
So I asked my father, who flew various large aircraft for the USAF from 1943 to
1967. He wrote:

"There are just two issues involved in losing an engine in a four engine
aircraft.....thrust and control. The C-54 was designed to function almost
completely normally on three engines. I don't remember the actual numbers,
but assuming normal cruise to be 160 mph on four, you might lose as much as
10 mph if one fan went out. IOW, the impact on performance would have been
negligible.

In terms of lateral control, especially near or on the ground, loss of an
inboard would have been preferable to loss of an outboard.

When you got into loss of two engines, it got a lot more sticky if they were
both the same side. If you lost one on each side, it wouldn't make hardly
any difference whether one was inboard and the other outboard or vice versa
as long as you remembered that your operating outboard engine would have a
tendency to want to turn the plane towards the inboard. Apart from that,
you were running essentially a twin with not too much margin of error left
for you."

I assumed if you lost both engines on one side, you'd be in the same situation
as if a twin lost one engine.... you would have an immediate and unmistakable
change in your flight situation requiring some sort of action. What I didn't
know was how much stronger the reaction from a four engined aircraft might be if
it lost an outboard vs an inboard engine.



--
Mortimer Schnerd, RN

VE