# What is the calculation for N1/Takeoff Speeds?

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Hey folks,

Just wanted to code a tiny conversion thing so I can use it to be more realistic on games and maybe real life in the future.

I'm not looking for a plane specific but more a general conversion lets say for a 737-800 maybe.

Thanks

-Dream

I always use N1 of 92% for takeoff in the 737-800.  Since this aircraft has a N1 knob and auto throttle will respond to N1 settings.  I always say "Keep your jet mechanics happy and not use 100% on the thrust levers."

On 3/24/2018 at 2:53 PM, charliearon said:

I always use N1 of 92% for takeoff in the 737-800.  Since this aircraft has a N1 knob and auto throttle will respond to N1 settings.  I always say "Keep your jet mechanics happy and not use 100% on the thrust levers."

Do you still use 92% when you're hot and high?  I'm asking out of curiosity as I currently fly 777's and DC-10's, but never 737's.  Do 747-800's have enough power to derate to 92% all the time?

4 minutes ago, Mace said:

Do you still use 92% when you're hot and high?  I'm asking out of curiosity as I currently fly 777's and DC-10's, but never 737's.  Do 747-800's have enough power to derate to 92% all the time?

Let's just say that whatever aircraft I'm flying, jet, prop, whatever, I will use way less than 100% power for takeoffs. I have found that most big aircraft will happily take off using 90% N1.  That is assuming I am not using 100% full fuel tanks.

I too use about 92 pct, except for short field takeoffs.  I like to apply the power smooth and slowly, just like I drive, to allow the engine the time to catch up.

John

You're going to have to find a performance manual for what your flying.

Here's a very basic explanation.

50 degrees C is considered max derated thrust.  So whatever engine N1 occurs at 50 degrees is what you would set to.  Then you would have to check if the plane can takeoff from that airport at that temperature.

If it can't then you have to lower the temperature until it can.

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