Date:         29 Jun 98 02:38:22 
From:         Hugh Dickson <>
Organization: CCCC
References:   1
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Donald Mc Lean wrote:

> In answering a question on use of reverse thrust , asymmetric use of
> reversers Mandy Bartels said that the 'power' on the b747-400 is reduced to
> 'idle' and the reversers are operated in that position to minimise the
> opposition to brakes or words to that effect.
> Surely the 'thrust' is reduced to 'zero' with the reversers at the interlock
> position, ie , so no forward or reverse thrust is produced. This is a far
> cry from 'idle' thrust that on a cold winter morning can be over 1200lbs per
> engine (approx 5000 total) that works against the brakes on landing rollout.
> Its not just terminology.    cowboy

Aloha,    I have seen mfg. reports that say compressor cascade vanes
and turbine reverser blocker doors can give up to about a 40% reverse
thrust.  Last I heard these same engines at idle gve about 15% fwd.
thrust at idle.  I would posit that a 25-35% difference is significant.

Regards,   Hugh