Where does the cooling air for Rolls Royce turbine blades come from and what controls it?

I was just wondering how the cooling air gets to the turbine blades...





Does anybody know?|||I studied the RB-211 when flying 747 airplanes fitted with these engines -

I do recall instructor mentioning the hollow turbine blades and cooling air -



If I recall well, was air bled from the compressors (maybe N2) -

Likely to be controlled by the electronic FCU -

Source was probably from the AFC "air flow control" - (N2, bleeds and IGV)

I do not recall exactly, slept most of the time in the powerplant class -

RR loves to make simple things complicated -

I prefer CF6 and JT9D motors anyway...!



Next time I shall go in my cellar, dust off my old 747 RR manuals -



If you know, why ask...?

Forner examiner and instructor, I can dig "gee wizz" questions too -|||Why are you asking questions that you already have the answers to?





Are you related to Caretaker by chance?