737 MAX 8 Cruise Performance Question
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Joined: May 2025
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From: Belgium
737 MAX 8 Cruise Performance Question
Hi,
I'm writing a thesis in college about the known issue with the MAX family aircraft where de-icing fluid tends to get stuck in the tailcone due to a clogged drain hole. As part of the operational impacts section of the thesis, I'd like to make a simulation of what effect this extra weight in the tailcone has on fuel economy, but I'm not 100% sure on how to do this accurately.
Calculating the extra fuel burn caused by the extra total weight is simple. The long range cruise table in the FCOM gives values for fuel burn at FL310 at GW's of 80.000 kg and 85.000 kg. By interpolation, I can find the fuel burn for a gross weight of 80.000 kg + 250 kg of fluid in the tailcone.
However, there must be other effects that have to be considered. My question is: what are these effects / what am I missing?
How would the AFT relocation of the CG caused by the fluid in the tailcone affect the cruise performance? Seeing as the CG would then move closer to the CP, the horizontal stab would have to create less downforce to keep the aircraft in balance. This means the wings have to create less lift, so this should actually increase the efficiency and result in less fuel burn. Is there a way to calculate how much less this would be?
Many thanks!
I'm writing a thesis in college about the known issue with the MAX family aircraft where de-icing fluid tends to get stuck in the tailcone due to a clogged drain hole. As part of the operational impacts section of the thesis, I'd like to make a simulation of what effect this extra weight in the tailcone has on fuel economy, but I'm not 100% sure on how to do this accurately.
Calculating the extra fuel burn caused by the extra total weight is simple. The long range cruise table in the FCOM gives values for fuel burn at FL310 at GW's of 80.000 kg and 85.000 kg. By interpolation, I can find the fuel burn for a gross weight of 80.000 kg + 250 kg of fluid in the tailcone.
However, there must be other effects that have to be considered. My question is: what are these effects / what am I missing?
How would the AFT relocation of the CG caused by the fluid in the tailcone affect the cruise performance? Seeing as the CG would then move closer to the CP, the horizontal stab would have to create less downforce to keep the aircraft in balance. This means the wings have to create less lift, so this should actually increase the efficiency and result in less fuel burn. Is there a way to calculate how much less this would be?
Many thanks!
