King767 From , joined Dec 1969, posts, RR: Posted (12 years 1 month 2 weeks 2 days 21 hours ago) and read 4809 times:
I am sorry if this has been discussed before (I tried the search function, but I did not get what I was looking for). I think I might have an understanding of what they are, but I am probably wrong. Could someone please explain what they indicate?
Thanks, Tom
P.S. Seems the Airport code search is down for the moment, but could someone please tell me which airport is XNA?
Tuffty From United Kingdom, joined Mar 2001, 92 posts, RR: 0 Reply 1, posted (12 years 1 month 2 weeks 2 days 20 hours ago) and read 4763 times:
they relate to the speed at which sections of the engine are rotating. N1 is your fan speed, N2 is your LP speed and N3 is your HP speed. they are normally given as a percentage though. They may differ from engine to engine though which part they relate to (the ones that i gave you were for an RB211)
Ajaaron From United Kingdom, joined Nov 2000, 113 posts, RR: 0 Reply 2, posted (12 years 1 month 2 weeks 2 days 20 hours ago) and read 4766 times:
This indicates the %age of the maximum RPM of various turbines on the jet engine as follows:
N1 is the speed of the big fan at the front of the engine which can be seen from outside.
N1 can sometimes exceed 100% on take off. Pilots will sometimes use this as a direct indication of power, so for example typically will use 55-60% N1 on approach, although they do not actively watch this to set power while on approach - when u fly the plane u adjust power automatically to suit the flight profile.
N2 is the turbine inside the engine and N3 is a turbine further in the core of the engine.
When the engine is started N2 starts to turn which drives N1 and one can see the % increases on the EICAS screens in the cockpit.
Tuffty From United Kingdom, joined Mar 2001, 92 posts, RR: 0 Reply 6, posted (12 years 1 month 2 weeks 2 days 2 hours ago) and read 4704 times:
Yeah thats right because no one else makes a triple spool engine as such, most others run the fan as part of the lp spool. if you do an air start you would look at your N1 on non RR engines to ensure that the engine has begun to turn. on RR engines though you'd look for your N2 to build
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