More RR EPR confusion
Flew with a guy (on a check dammit) who asked me why, in an idle descent (on a A330 with rollers) the EPR reads less than 1.0.
I said ... `cause in effect, work is being done on the engine, as opposed to the engine doing work. i.e. the air is turning the engine iso vv, hence P5 (at the front) is experiencing more P then P2 (at the back), and EPR = P2/P5
He said... `Actually, it`s because outlet pressure (P2) is measured only in the hotstream duct (which I agree is true), and is compared to the entire coldstream (P5)
So I said... `Yes sir, of course sir, may I have another please sir` And lowered head, placed tail between legs etc.
As I see it, both answers are correct, but is one more correct than others?
Disclaimer> Any incorrect Pn labelling (where n in an integer b/t 1 and 6) please forgive, you know what I mean.
[This message has been edited by jtr (edited 20 September 2000).]