I've got a couple of questions re: engine starting and RPM. I have a source which says the following:
- Addition of fuel - 15% of max. rpm
- Self-sustaining - 35% of max. rpm
-Idle - 55% of max. rpm
Photo © Bevin Shively
1. I always thought 55% was a high N1 for idle and the photo above shows 68% N2 and 26.3% N1. So do the numbers I have listed above the photo actually refer to N2 speeds?
Photo © Enrique Puche Aznar
2. The above photo shows 91.2% N1 and 95.7% N2 so does the N1 'catch up' to N2 as engine RPM increases?
3. And lastly, what are some typical N1, N2 or EPR values @ idle of common engines eg: JT8D, JT9D, CF6, RB-211, CFM56, GE90 etc...
Any info is appreciated, thanks