Topic Author
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Joined: Tue Aug 08, 2000 10:34 am

Engine Spool Rotation Direction

Sat Oct 21, 2000 1:06 am

I am wondering a few things.

Do modern high bypass engines all spool in the same direction? And do the fans rotate in the same direction as the basic turbine engine?

I know about the UDF engines with counter (or contra) rotating fans, and the turboprops with the same (counterrotation of props) on rare aircraft such as the Bear Bomber and similar transport from the Soviet geography. USA experimented with them too.

But what direction do the engines of today rotate?

Posts: 609
Joined: Wed May 26, 1999 10:07 am

RE: Engine Spool Rotation Direction

Sat Oct 21, 2000 3:04 am

As I recall it is counterclockwise, except for some of the older RR engines, you know the english, always something different. Then again they also build electrical systems without fuses, so what do we expect!

Aer Lingus
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RE: Engine Spool Rotation Direction

Sat Oct 21, 2000 3:53 am

Well most engines' low pressure compressors (outer fan) spin anti-clockwise with the exception of the RR Trent. I think its all models although I'm not sure. I do know that its like that for the RR Trent 800 on the 777's

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RE: Engine Spool Rotation Direction

Sat Oct 21, 2000 3:54 am

The P&W engines (JT3D, JT8D, JT9D, PW2000, and PW4000) and GE engines (GE90, CF6 and, CFM56) have the low and high pressure rotors rotating in a clockwise direction as you look forward from the rear of the engine. Some of the P&W Canada engines with multiple spools have them rotating in both directions. The Rolls Royce engines (RB211, Spey, Tay, and Trent) have the low, high, and intermediate rotors for those engines equipped with 3 spools rotating in a counterclockwise direction as looking forward from the rear of the engine.
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Joined: Tue Mar 21, 2000 6:25 am

RE: Engine Spool Rotation Direction

Tue Oct 24, 2000 6:45 am

Just for curiousity: The RR Pegasus engine in the Harrier VTOL (vertivcal take-off and landing) fighter is a two spool turbofan engine. The High pressure and low pressure sections rotate in OPPOSITE directions.
This unique design feature was chosen because it reduces or eliminates the otherwise nasty gyro effects which would make hovering flight much more difficult to control.
Best regards, Preben Norholm
Always keep your number of landings equal to your number of take-offs
Topic Author
Posts: 817
Joined: Tue Aug 08, 2000 10:34 am

RE: Prebennorholm

Tue Oct 24, 2000 10:41 am


Thank you for your information. The Harrier is an interesting aeroplane. You probably know that the J-79 turbojet with the aftfan used in the Convair 990 was one with the turbojet spool rotating opposite in direction than the fan.

But probably today most fans rotate the same as the rest of the engine. This is what I am hearing here.


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