Guest

### N1,N2,N3

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
Posts: 91
Joined: Tue Mar 13, 2001 8:03 pm

### RE: N1,N2,N3

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
Posts: 140
Joined: Thu Nov 02, 2000 9:31 am

### RE: N1,N2,N3

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.

hope that gives u food for thought!

Guest

### RE: N1,N2,N3

Ajaaron,

How can the N1 exceed 100%?

VC-10
Posts: 3549
Joined: Tue Oct 26, 1999 11:34 am

### RE: N1,N2,N3

100% is a nominal figure

N1 is the Fan Spool [Rotor] (compressor AND turbine)

N2 is the Intermediate Spool (or HP Spool if a twin spool engine)

N3 is the HP Spool.

sabenapilot
Posts: 2451
Joined: Sat Feb 26, 2000 6:18 pm

### RE: N1,N2,N3

N3 is only used on RR engines as far as I know.

Tuffty
Posts: 91
Joined: Tue Mar 13, 2001 8:03 pm

### RE: N1,N2,N3

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

### Who is online

Users browsing this forum: AirFiero, Bing [Bot], Mangs, prestwick, psimpson, stackelberg and 11 guests

### Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos