
How Qantas Ferried an Engine on the Wing of a 747 - bootload
http://www.flightradar24.com/blog/how-qantas-ferried-an-engine-on-the-wing-of-a-747/
======
dingaling
Fair dues to QANTAS for milking this on social media but spare-engine ferrying
was common from the dawn of the jet age.

The 707, 747, DC-8, DC-10, TriStar and VC-10 all had an underwing hardpoint
for the extra engine and carrying it was fairly routine; just apply the
compensations laid-out in the flight manual.

Four-engined TriStars looked funny...

It is rare nowadays due to the ubiquity of twin-engined airliners which have
neither the underwing space nor the take-off engine-failure margin to ferry a
spare. Instead their spare engines are stripped and sent in freighters,
usually by the engine manufacturer who provide power-by-the-hour contracts to
the airlines.

~~~
peckrob
I seem to recall I once flew on an L-1011 TriStar as a kid that ferried an
engine. It was out of Atlanta but I can't remember if we were going to Los
Angeles or San Francisco. That was probably 25 years ago, so not sure which it
was.

As a sidenote, the L-1011 is still one of my favorite planes. It was one of
the most technologically advanced airliners ever created when it was unveiled;
lots of things about it were way ahead of its time. It's a shame that the
competition with the Douglas and the DC-10 nearly bankrupted both Lockheed and
Douglas. Airlines played both companies against each other and nearly killed
both. Lockheed ended up exiting the commercial business while Douglas merged
with McDonnell.

There's a great long article on the the L-1011 published a few months ago:
[http://www.airlinereporter.com/2015/09/requiem-trijet-
master...](http://www.airlinereporter.com/2015/09/requiem-trijet-masterpiece-
lockheed-l-1011-tristar/)

~~~
niccaluim
The L-1011 is/was amazing. It was the first airplane to be certified for full
autoland in zero visibility conditions.

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teleclimber
Seeing a 747 with 5 engines reminds me of seeing GE's N747GE testbed aircraft
in Mojave, which usually flew with a odd engine configurations. I can't
remember if they used the 5th pylon at all and most pictures show an
experimental engine on the inboard pylon. Sometimes a very large engine[1],
sometimes a small one[2].

One time they tried to ferry the aircraft from Mojave to Victorville with only
three engines (they must have removed the experimental engine for whatever
reason). They attempted the take-off but had to abort. It was quite a sight
anyways. They went back to the hangar and we saw it fly away with four engines
a few days later.

GE now has a second 747 to play with.[3]

[1]
[http://www.jetphotos.net/photo/45634](http://www.jetphotos.net/photo/45634)

[2]
[https://en.wikipedia.org/wiki/File:Ge-747-N747GE-020404-01.j...](https://en.wikipedia.org/wiki/File:Ge-747-N747GE-020404-01.jpg)

[3] [http://www.sieinc.com/into-thin-air-the-lofty-side-of-jet-
en...](http://www.sieinc.com/into-thin-air-the-lofty-side-of-jet-engine-
testing/)

~~~
ak217
I'm guessing they would never use a 5th pylon when engine 2 is missing and
replaced by a potentially misbehaving or inoperable test engine. The 5th pylon
could never accommodate a running engine since it's just an external cargo
mount, not a full blown engine mount with all the necessary connections.

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braidenjudd
My father works for QANTAS, has for 40 years. He said they used to do one,
once a month on the older jumbos. But with the newer ones 400s, QANTAS just
retired one to the desert with the 4 original engines still on it. Meaning it
never needed an engine change in its entire operating life.

------
eddyg
> The fifth pod option is restricted to Qantas’ Rolls-Royce-powered 747s

Why the restriction to RR-powered 747s?

~~~
drewkett
I would guess it's a flutter problem. Flutter is when an aircraft becomes
dynamically unstable due to the interaction between the aircraft structure and
the air around it. Certain aircraft are more prone to flutter than others such
that it occurs at speeds closer to its max airspeed. The type of engine and
how it's attached to the wing can have a big effect on flutter since it's a
large mass that's hanging off the wing. As a result the same aircraft with
different engines can have significantly different flutter properties.

[https://en.m.wikipedia.org/wiki/Aeroelastic_flutter#Flutter](https://en.m.wikipedia.org/wiki/Aeroelastic_flutter#Flutter)

~~~
stergios
An oscillation builds up in the wing span to the point where the wing self
destructs. Here's an video example from the development of the 747:

[http://www.airspacemag.com/videos/category/flight-
today/wing...](http://www.airspacemag.com/videos/category/flight-today/wing-
flutter-on-a-747/)

------
sandworm101
Why not use a full fairing over a complete engine?

~~~
emeraldd
Probably less drag to let the air flow through an "empty" engine rather than
to have a large obstruction on the wing.

~~~
sandworm101
I don;t know. Cramming all that air down the tube of a fanless engine doesn't
seem very efficient compared to the clean cone of a fairing.

~~~
sbierwagen
Adding a bigger fairing will increase the cross section of the object,
increasing the form drag. (Bigger things push more air out of their way when
moving)

[https://en.wikipedia.org/wiki/Parasitic_drag#Form_drag](https://en.wikipedia.org/wiki/Parasitic_drag#Form_drag)

------
dwightgunning
I'm also curious about what had happened the engine that needed to be
replaced.

Is the 6T engine the heaviest non-visible part on a 747?

~~~
jrgv
From the article: "The disabled engine in Johannesburg will make its way back
to Sydney at a much slower pace by ship."

~~~
dwightgunning
Sorry, I meant what happened to the engine that meant it needed to be
replaced. It doesn't sound like these engine replacements happen too often so
I figured it was in some way noteworthy.

