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Old 30th Jan 2014, 21:23
  #25 (permalink)  
Bye
 
Join Date: Aug 2007
Location: Derby UK
Age: 59
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Almost all jet engines have bleed control valves. Nothing to do with it being a bleedless aircraft design.
then why claim its a bleedless engine in the first place

it has everything to do with the claim of being a bleedless "engine" if you understand the claims made for why its bleedless.

There is one bleed on the engine for the engine inlet cowl anti-ice system by the way
the HP3 take off butterfly valve for anti-ice is not considered a bleed, it is a deliberate take off, selectable by the pilot of hot air, there are many such take offs of air through the gas path for various uses non of which are considered or even described in the drawings as "bleeds" even though the gas ends up overboard if used.

you may call it a bleed, that is your right but it is not a bleed.

bleeds are generally used to described un-intentional or un-wanted loss of gas flow, removing the gas from the 5 bleeds is not for use but is to manage the surge risk and is thus un-wanted as when in operation they lower the efficiency of the compressor and thus increase the fuel consumption.

on the T1000 as we now waste that energy dumped over board, instead of using it to pressurise the cabin, that energy has to come from somewhere else, that being the VFSG. fortunately in the cruise phase the bleeds will stay shut and the engine is operating at optimum for the phase for the longest time.
Bye is offline