Engine question

[Jester986]

So I'm used to dealing with free turbine turboshaft engines and not turbojet engines. But yesterday doing a start up in the c-101 I noticed that the N2 gauge started spooling before the N1. From what I understand the N1 is the compressor section so thats what the starter should be turning and the N2 should spool later as power develops. So I'm just curious if this is a bug, or maybe its a fixed turbine in the 101 so they're spooling at the same time and its just different ratios going on in the gauges, or something else entirely?

[Vibora]

Hi Jester. What you are saying is just the opposite of what it really is. The C-101 is equipped with a Garrett turbofan with two mechanically independent spools.

Please take a look at our startup training mission and at our manual to understand how the start sequence develops in the C-101. It’s very clearly explained in the startup mission, and the engine described in the manual.

[Rudel_chw]

N1 is the rpm of the Low Pressure Fan-Compressor, N2 is the rpm of the High Pressure Turbine; the starter is connected to the latter, thats why N2 spools first.

[Jester986]

Thanks Vibora and Rudel! It's just opposite of what I'm used to seeing and was curious.

[enigma6584]

Okay, so here is a stupid question; when flying around and I want to adjust engine rpm to a certain level, which do I use, N1 or N2?

[purpi]

Okay, so here is a stupid question; when flying around and I want to adjust engine rpm to a certain level, which do I use, N1 or N2?

 

N1 :doh:

Edited November 2, 2019 by purpi

[enigma6584]

Thanks.

[Vibora]

Jet engines (turbofan) thrust is managed using N1 or EPR.

[gulredrel]

Yes, everything great with the C-101.

 

If you are are used to the L-39, that's the thing that changes the logic of needle description. Don't have a clue, why Russian, or Czech, engineers designed the L-39's RPM gauge the different way.