N1 profile for breakaway
Thread Starter
Join Date: Jun 2009
Location: USA
Posts: 3
Likes: 0
Received 0 Likes
on
0 Posts
N1 profile for breakaway
I am a student and would like the following info to validate my emission model.
I would like to know N1 profile from 0 kts - breakaway i.e., still to taxi at MTOW. By profile I mean the thrust level and the duration for which it is maintained.
For example, 733 - 33%N1(10-15 seconds)(for breakaway) - 22%N1(thereafter for taxing).
I need this for B737, B757, B767, B777 and B747. Approximate range for each of the parameter( N1, time) is good enough.
Thanks
I would like to know N1 profile from 0 kts - breakaway i.e., still to taxi at MTOW. By profile I mean the thrust level and the duration for which it is maintained.
For example, 733 - 33%N1(10-15 seconds)(for breakaway) - 22%N1(thereafter for taxing).
I need this for B737, B757, B767, B777 and B747. Approximate range for each of the parameter( N1, time) is good enough.
Thanks
Join Date: Aug 2007
Location: Seattle KBFI
Posts: 117
Likes: 0
Received 0 Likes
on
0 Posts
Too many variables to give you a real accurate answer (aircraft gross weight, any slope on the ramp or taxiway, taxiing with a tailwind, airport temperature/elevation for how much thrust you have at ground idle)
But for B-744 at max gross weight, no slope on the ramp, etc you might have to use up to 40% N1 (GE-CF6 series) for 3-5 seconds to really get it rolling, then just about idle (26%) so perhaps 30% to keep the speed where you want it.
Light weight aircraft will break away and accelerate at idle thrust, and you will have to ride the brakes to slow it down, or just taxi on 2 engines instead of starting all 4.
Perhaps a more useful question is what kind of fuel burn is planned for taxi. Somehow the number that is quoted to us for planning is 45kg per minute as an average. Probably less when empty/light weight, and more if you are heavy and are using above idle thrust.
But for B-744 at max gross weight, no slope on the ramp, etc you might have to use up to 40% N1 (GE-CF6 series) for 3-5 seconds to really get it rolling, then just about idle (26%) so perhaps 30% to keep the speed where you want it.
Light weight aircraft will break away and accelerate at idle thrust, and you will have to ride the brakes to slow it down, or just taxi on 2 engines instead of starting all 4.
Perhaps a more useful question is what kind of fuel burn is planned for taxi. Somehow the number that is quoted to us for planning is 45kg per minute as an average. Probably less when empty/light weight, and more if you are heavy and are using above idle thrust.
