How long will it last?
Thread Starter
Joined: May 2004
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From: Flagrant Harbour
How long will it last?
Suppose you shut a jet engine down in the cruise how long would the engine windmill if the shutdown was due to the failure of the oil pressure pump? ie there was zero oil pressure and even windmilling there was zero oil pressure.
KISS please.
KISS please.
Joined: Mar 2000
Posts: 8,571
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From: Arizona USA
Well, it depends......
Rather short with RB.211 series engines.
NO oil prerssure = BIG time troubles.
OTOH, with a shutdown with minimal oil pressure...it can rotate for a rather long time.
As in two hours...minimum.
NO oil prerssure = BIG time troubles.
OTOH, with a shutdown with minimal oil pressure...it can rotate for a rather long time.
As in two hours...minimum.
Joined: Jun 2004
Posts: 1,843
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From: Australia
Hopefully, it will cease rotating as soon as possible for 2 good reasons -
(1) If there's no oil pressure, further damage to the engine will be minimised making it much less expensive to repair,
(2) Windmilling drag is greater than for a stationary engine, thus performance will be better.
Regards,
Old Smokey
(1) If there's no oil pressure, further damage to the engine will be minimised making it much less expensive to repair,
(2) Windmilling drag is greater than for a stationary engine, thus performance will be better.
Regards,
Old Smokey
Joined: Oct 2002
Posts: 345
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From: The dark side of the moon
Old Smokey
I have been taught that a shut down jet engine produces about the same amount of drag whether it is windmilling or not!
Could this just be a case for the low by-pass jet?
But, still I feel a high by-pass jet will have the same results, due to the fact than all shut down jets effectively become sheets of metal face on to the relative wind!!!
I have been taught that a shut down jet engine produces about the same amount of drag whether it is windmilling or not!
Could this just be a case for the low by-pass jet?
But, still I feel a high by-pass jet will have the same results, due to the fact than all shut down jets effectively become sheets of metal face on to the relative wind!!!
Joined: Feb 2003
Posts: 496
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From: Scotland
You want to "Keep It Simple" 7FF?
Well, the simple answer is, as 411A says, "It all depends which engine you mean". (Me, agreeing with 411A, WIHIH??!)
The engines I have flown have varied between Hours and Minutes with 0 oil pressure, depending on the lubrication system.
Well, the simple answer is, as 411A says, "It all depends which engine you mean". (Me, agreeing with 411A, WIHIH??!)
The engines I have flown have varied between Hours and Minutes with 0 oil pressure, depending on the lubrication system.
Joined: Jun 2004
Posts: 1,843
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From: Australia
Touch'n'oops,
It's nowhere near as significant as a windmilling propeller, BUT, the windmilling engine is extracting energy from the airstream (Something is making it turn, and energy doesn't come free). The Performance Manuals for various heavies give accountability for the worst case, this being windmilling failed engine/s. (Usually found in the Performance Manuals in association with the offset rudder drag coefficient, which of course also goes along with a failed engine).
I can only believe the books, I've shut down many during test flying, but so far have been unable to make one stop rotating altogether - don't want to thanks!
Regards,
Old Smokey
It's nowhere near as significant as a windmilling propeller, BUT, the windmilling engine is extracting energy from the airstream (Something is making it turn, and energy doesn't come free). The Performance Manuals for various heavies give accountability for the worst case, this being windmilling failed engine/s. (Usually found in the Performance Manuals in association with the offset rudder drag coefficient, which of course also goes along with a failed engine).
I can only believe the books, I've shut down many during test flying, but so far have been unable to make one stop rotating altogether - don't want to thanks!
Regards,
Old Smokey
