With the fuselage plugs forward of the wing, would this mean the engines are closer to CG, therefore no need for MCAS?
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asked Jan 4, 2020 at 9:16
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3 Answers
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The fuselage length is immaterial. The problem of the Max series relates to the positions of the engines versus the wing, and their aerodynamic interference near the at high alpha. The amount of fuselage ahead of the wing or behind the wing is not a major factor here.
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The MAX 10 fuselage is also lengthened behind the wing:
In October 2016, Boeing's board of directors granted authority to offer the stretched variant with two extra fuselage sections forward and aft with a 3,100 nautical miles (3,600 mi; 5,700 km) range reduced from 3,300 nautical miles (3,800 mi; 6,100 km) of the -9.
Basically the center of gravity of MAX 7,8,9 and 10 is in the same location (range) in respect to the wing, or mean aerodynamic chord (MAC) of the wing to be more precise. As the engines are essentially the same in all MAX variants, and so is the location of them, the engine location from CoG is pretty much precisely the same.
The need for MCAS cannot be solely determined by CoG of MAX 10, as the longer fuselage may have some other effect on stability, but my personal guess is, some kind of maneuvering augmentation is necessary.
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1$\begingroup$ Wasn’t the entire point of MCAS to make the aircraft “feel” like the NG? Due to the engine configuration they had “easier stick forces” and therefore needed MCAS, so if the engines are not placed forward and up, then there’s no need for it? $\endgroup$ Jan 4, 2020 at 11:06
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$\begingroup$ But the engines on all MAX versions are "forward and up" @Firefighter1 $\endgroup$– Jpe61Jan 4, 2020 at 11:29
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$\begingroup$ i apologize, thanks for that. If the Max 10 is the Max 9 with a longer fuselage, wouldn’t that cross out the engine configuration? Doesn’t the new landing gear have a role in this as well? $\endgroup$ Jan 4, 2020 at 13:25
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1$\begingroup$ @Firefighter1 The new landing gear has no effect on engine location. It could have, but Bojong didn't want to invest in designing a new engine mount just for MAX 10. To be fair, that's understandable, saving on MCAS was not. $\endgroup$– Jpe61Jan 4, 2020 at 22:52
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$\begingroup$ wouldn't the longer fuselage mean that the proportional difference between cg and engine location is less? $\endgroup$– AbdullahJul 10, 2020 at 11:34
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It looks like the 737 MAX 10 will also have MCAS:
The Boeing MAX 10 will contain an upgraded version of a flight handling system that has been seen as a key factor in both crashes involving casualties of 346 people.
The mechanism - the Maneuvering Characteristics Augmentation System (MCAS) - has been tweaked to give the pilot more control. But regulators, including the Federal Aviation Administration (FAA), have yet to sign off on the changes.
"I'm honoured to take this aeroplane on its first flight and show the world what you've put your heart and soul into," 737 chief pilot Jennifer Henderson told the employees gathered for the debut of the first 737 MAX 10 at the company's Renton, Washington factory.
(aviationpros.com, emphasis mine)
As far as I could find, there is no official statement from Boeing on this. They only say
MCAS, or Maneuvering Characteristics Augmentation System, is a flight control law implemented on the 737 MAX to provide consistent aircraft handling characteristics at elevated angles of attack in certain unusual flight conditions only.
without distinguishing between the different variants. Their 737 MAX 10 page does not include any details on MCAS.
answered Jul 10, 2020 at 12:19