If N1 idle is 30%, will flying idle at very high speeds force the fan to go higher than 30%? (for example idle while descending fast)

And if no, why not?

  • 1
    $\begingroup$ yes it will, because then it will create less drag. $\endgroup$ – Peter Kämpf Sep 3 '17 at 17:10
  • $\begingroup$ When an aircraft is descending at idle, some engine controls actually keep the idle speed (rpm) high, at least in military aircraft. $\endgroup$ – Penguin Sep 4 '17 at 12:47

Yes, N1 should increase as the plane reaches higher speeds. This means that the blade speed will increase, therefore, increasing N1. Now because the engine setting is constant (throttle), this means that only a slight increase in the amount of thrust will happen.

  • $\begingroup$ Why does N1 increase with increasing airspeed? $\endgroup$ – Koyovis Sep 6 '17 at 21:42
  • $\begingroup$ N2 doesn't increase does it? $\endgroup$ – Invariant Sep 6 '17 at 21:57
  • $\begingroup$ @Koyovis you can refer to this to see what N1 is: aviation.stackexchange.com/questions/14690/what-are-n1-and-n2 It's basically self-explanatory because as the airspeed is greater, the fan will speed up. $\endgroup$ – Seth Deegan Sep 10 '17 at 18:41
  • 1
    $\begingroup$ You can read the post above as well @Invariant . The N2 will increase as it is once again, the speed of the blades in the high-pressure shaft whereas N1 is the speed in the low-pressure. Either way, both should increase. $\endgroup$ – Seth Deegan Sep 10 '17 at 18:46
  • $\begingroup$ @SethDeegan I know what N1 stands for, that wasn't my question. $\endgroup$ – Koyovis Sep 10 '17 at 19:30

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.