GE90-115B engine analysis and my grand finale

GE90-115B engine analysis and my grand finale

Hello again, it’s been a long time since 20.1, which I published my study of the engine performance and fuel management. Last time, I did a static runup of the engine on the 772, and the fuel flow increased almost linear. This time, I with hundreds of 77W flights logged and a trend line, I get to understand the point of the engine start to burn excess amount of fuel because of the increase of the mass flow of the air. Here is the data, be careful, the fuel burn is kG/H per one engine, runup at 100 ft of elevation.


Figure 1: The relationship between throttle percentage and fuel flow per engine.
Understanding the data

Comparing to the old 77W, even if the weight and balance still says that the estimate fuel burn at cruise is 7080kG/H, but the devs have nerfed the fuel burn by approximately one per cent. It means that at cruise, the engines use about 100kG of fuel per hour. According to the trend line, it looks like the engine will start burning extra fuel once the throttle exceeds 70%. So, when you pick cruise altitude while minimising fuel burn, you should also keep your throttle below 70% like the old 77W. In real life, Boeing didn’t make a different wind-altitude trade chart when then develop 772 into 77W, but Infinite Flight might not model these planes precisely like what they behave in real life. So, be careful at your end of step-climb, if your fuel flow starts to increase by a lot, stop climbing.

Conclusion

Flying with these astonishingly large engines isn’t different from the 737 ones. Maintain positive control, and step climb correctly. Then it should behave like the 772 that you are used to flying. I will not be uploading any engine analysis anymore. I have fought my way to 3 ground lessons with an end of course stage check for my private pilot licence. I have waited for this moment for three years throughout the groundings, termination, weather, and quarantine. After finishing my private pilot, I shall fulfil my promise of advance into PC flight simulation. I either will pick MFS2020 or DCS after I obtained my RTX 3090. My wish after passing the real check ride is not to use so much time in my instrument, commercial, and multi. I have one year left before my visa expires. I had better hurry up.

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Thank you for this

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you are welcome

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Good luck on your journey!

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