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Old 29th May 2004 | 16:22
  #13 (permalink)  
big bus driver
 
Joined: Jul 2000
Posts: 21
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Hi A-Floor,

In the T700, and all other RR engines the shafts rotate the same way to reduce relative speeds between the shafts and hence preserve bearing life. (i.e say IP shaft rotates at 7000rpm, HP at 10000rpm when shafts rotate same way, the intershaft bearings spin at 3000rpm, compared to 17000rpm if they were contra-rotating)

There was talk of the T900 for the A380 being RR's first contra-rotating engine as an improved bearing design had been produced. It has the advantage of reducing weight too as you can do away with a 2 stages of NGV's. Don't know if this design is going ahead for production or development only though.

Brgds,
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