Welcome Guest. Sign in or Signup

1 Answers

What do N1 and N2 stand for?

Asked by: 27185 views , , , ,
Aerodynamics, Aircraft Systems, Commercial Pilot

Hello Pilots! I see in turboprops and jets N1 and N2 inside cockpit, what do they stand for??

Ace Any FAA Written Test!
Actual FAA Questions / Free Lifetime Updates
The best explanations in the business
Fast, efficient study.
Pass Your Checkride With Confidence!
FAA Practical Test prep that reflects actual checkrides.
Any checkride: Airplane, Helicopter, Glider, etc.
Written and maintained by actual pilot examiners and master CFIs.
The World's Most Trusted eLogbook
Be Organized, Current, Professional, and Safe.
Highly customizable - for student pilots through pros.
Free Transition Service for users of other eLogs.
Our sincere thanks to pilots such as yourself who support AskACFI while helping themselves by using the awesome PC, Mac, iPhone/iPad, and Android aviation apps of our sponsors.

1 Answers



  1. Wes Beard on Feb 16, 2012

    This answer is specific to a turboprop and not to a turbojet or turbofan engine.  Although the same principles apply, the N1 and N2 speeds are taken in different places on the three types of engines.
     
    The N1 is a speed sensor inside the combustion chamber measuring the rotational rate of the turboshaft and not the propeller speed.  On some turboprop aircraft it is labeled as a N1 or a Ng (gas generator).
     
    The N2 is a speed sensor measuring the rotational rate of the propeller shaft.  It can be called N2 or Np on different turboprop aircraft.
     
    There is also two different types of turboprops.  There is a fixed shaft design where the turboshaft and the propeller shaft is directly connected through a gearbox.   The second type is a free turbine where the exhaust gas from the turbine section is routed to the front of the engine where it passed through a fanbox which is directly connected to the propeller shaft.
     
    Also on some turboprop aircraft the N1 and N2 are represented as a percentage instaed of a RPM rate.  This is easily done by dividing the current rotational rate by the maximum rated rotational rate.

    +4 Votes Thumb up 10 Votes Thumb down 6 Votes


The following terms have been auto-detected the question above and any answers or discussion provided. Click on a term to see its definition from the Dauntless Aviation JargonBuster Glossary.

Answer Question

Our sincere thanks to all who contribute constructively to this forum in answering flight training questions. If you are a flight instructor or represent a flight school / FBO offering flight instruction, you are welcome to include links to your site and related contact information as it pertains to offering local flight instruction in a specific geographic area. Additionally, direct links to FAA and related official government sources of information are welcome. However we thank you for your understanding that links to other sites or text that may be construed as explicit or implicit advertising of other business, sites, or goods/services are not permitted even if such links nominally are relevant to the question asked.