Rotation side of jet engine? / critical engine?

[WhySoTough]

Firstly. My questions are for the a320, but I'd imagine most jets are similar in this sense? Or?
What direction do the two engines rotate?
Is there a critical engine with jets?

Forgive my silly questions.

[B737900er]

The fan spins anti-clockwise, there is a white spiral on the cone of the fan to show you which way and if the fan is spinning.

I would tell you the answer to the critical engine question but to make you learn how to reference information, which is a required skill that is needed in this game, I recommend searching the definition of critical engine and read the basic mechanics of a jet engine and let you make up your mind

[DaveReidUK]

I'd imagine most jets are similar in this sense?

Not necessarily.

[hetfield]

On northern hemisphere anti clockwise, clockwise in southern hemisphere due to coriolis force

[enicalyth]

Not so... Hetfield is incorrect

Historically US engines rotated one way and European ones the other. So it all depends. For that reason 5 minutes before crossing from one hemisphere to the other first one engine on a twin is shut down and restarted spinning the other way and then the next. Which to shut down first depends on Airbus or Boeing. The RAF flew TriStars and had to land at Ascension before going on to Mount Pleasant because of this. It was known as going tech at Asi and aircraft always went tech at ASI. Great care had to be taken to offset Coriolis force on Triples eg Rollers go one way and PW the other. It was not unknown for the MD-11s to get confused and many handling mishaps were due to this cause. Funnily enough DC10s managed to get it sorted but then they had real flight engineers. MD eventually scrapped the fleet because of the risk of memory items being recalled incorrectly. With Quads it is possible to have them going both ways so none of this applies to A380/A340/B747. Only twins on EROPS or Engines Run Opposite Sides need this rule these days. Contra-rotating props were especially designed to cross the equator and the only worry was if they carried enough oil in the first place.

[Microburst2002]

The british engineers waited to see in what sense other countries engineers decided to make their fans rotate.

Then they designed theirs rotating in the opposite direction...

[FERetd]

Fans

Microburst 2002 - You mean the proper way!

[yotty]

Ah, but is that anti-clockwise VFR or VFF?

[z.khalid]

Just to clarify.
It's counter clockwise looking at it from the outside yes?
Or assuming rotation direction while sitting in cockpit?

[Lightning Mate]

Conventionally, the rotation direction is as viewed from behind the aeroplane.

[code0]

mmm just to add to that side of rotation of the turbine engine is a tricky one! sometime your fan N1 shaft turns one way and the N2 turns the other way to cancel out the centrifugal force. if not you will be internally pushing those rudders beyond the limit or might have to take a brick in ur travel bag!

so I guess the engine turns both ways! but the fan module or the N1 is what you see turning from outside! and the turning side depend on the manufacturer. And as someone said earlier the white snake on the tip of the fan module will tell u which way it turns.

Normally direction of the rotation is judged from the back of the engine facing the front of the airplane.

there are some contra-rotating and counter rotating configurations in turboprops and turboshafts. let me stop there!

Code0

[AirGek]

What if we fly along the equator? Is it up to the pilot or one engine has to spin one way and the other one the other way?

[EEngr]

Microburst2002:

The British engineers waited to see in what sense other countries engineers decided to make their fans rotate.

Then they designed theirs rotating in the opposite direction...

And when the Soviets copied British and American designs, they couldn't make up their minds,
So ....

[Smudger]

enicalyth... I'll have a pint of whatever you're drinking !

[john_tullamarine]

E - what's the world coming to ? You intent on giving away all the secret engineers' stuff ?

Love it.

[Smilin_Ed]

I'll have a pint of whatever you're drinking!

Make mine a quart!

Ed

[john_tullamarine]

sometime your fan N1 shaft turns one way and the N2 turns the other way to cancel out the centrifugal force. if not you will be internally pushing those rudders beyond the limit

Just had a re-read. Can you run the background to this statement past us once again ?

[FE Hoppy]

On some types it's changed on an odd or even day to balance wear. Windmill relight with unfavourable screw could demand the infamous tail slide manoeuvre!

[blackhand]

sometime your fan N1 shaft turns one way and the N2 turns the other way to cancel out the centrifugal force

Correct, the T53 Turboshaft engine does this as well, also keeps the anti torque control off the stops

[DaveReidUK]

sometime your fan N1 shaft turns one way and the N2 turns the other way to cancel out the centrifugal force. if not you will be internally pushing those rudders beyond the limit

Just had a re-read. Can you run the background to this statement past us once again ?

The Pegasus in the Harrier has LP and HP spools rotating in the opposite direction (to minimise gyroscopic precession in the hover, nothing to do with centrifugal force), but off the top of my head I can't think of any other examples.