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AeroSpark
28th Jan 2006, 22:17
I've heard this used on seveal cockpit videos and its been mentioned on Pprune etc but could someone explain it in a bit more depth for me? I'm assuming idle reverse means just deploying the reversers but wth the throttles at idle? Does this create a reverse thrust effect on the aircraft or does it just cancel out the positive thrust? And realise this is a very hypothetical question but what is the more efficient braking system, assuming the other was u/s, wheel brakes or reversers?
Thanks

Intruder
28th Jan 2006, 23:28
It is, indeed, deploying the reversers but remaining at idle thrust. It is a good trechnique in the final portion of the rollout so the brakes need not fight any forward thrust.

There is some amount of reverse thrust, but it may not be enough to actually move the airplane. Remember that with cascade reversers in high-bypass engines, reverse thrust is only about 40% that of forward thrust at best.

BOAC
29th Jan 2006, 07:09
A couple of other threads you can look at

http://www.pprune.org/forums/showthread.php?t=203085&highlight=reverse

http://www.pprune.org/forums/showthread.php?t=148132&highlight=reverse

NWT
2nd Feb 2006, 13:08
It will also depend onthe airlines own procedure as to 'normally' use reverse above idle. Watch the aircraft land at say LHR and you will notice some airlines will always use reverse above idle, others will just stay at idle. One reason is that the extra cost of fuel, andwear and tear etc when using full reverse, is more than the cost of the wear on the brakes. The modern carbon brakes do not wear asquick as the older style ones, and with the cost of jet fuel.....
Certain airports runways will almost always require a fair ammount of reverse, (on the larger jets) EWR is one that springs to mind.