4 ms·

Probably something to do with pitch. Imagine the center of lift(?) on the plane. If the engine is below that point, it would want to pitch up, if above, it woul

Probably something to do with pitch. Imagine the center of lift(?) on the plane. If the engine is below that point, it would want to pitch up, if above, it would want want to pitch down. Edit: Remember the whole Boeing Max problem was caused by placing the engines in a non optimal spot. (This is pure conjecture)

maxcan 5y ago
This is a big part of the answer. Usually when you're adding power, its because you want to go up so the last thing you want to happen is for the nose to go down. The higher up the engines are relative to the center of mass the more of a downward pitching moment you'll get. Also, I believe (and I'm very much not sure about this) but the above wing mounts like the Honda Jet can have nasty implications for flutter or some other structural issues if you aren't really careful. Its like the dynamic instability of trying to hold a stick at the bottom vs the top.
galgot 5y ago
Yes, the reason for the engine position on the 737 Max is that newer hi bypass ratio jet engines takes a lot of place. As the original 737 was designed for flying with much smaller diameter P&W JT8D, it stands quite low on the ground with relatively short landing gear . Thus, with newer and newer hi bypass engines , the engine pods had to be moved further up and front of the wing, which in turn changed the flight characteristics compare to the older versions. With the Max ,enough that it would have required client airlines to have to re-train their pilots on a new 737 flying differently than the original 737 they were trained for. And here enters the infamous MCAS which was designed to keep the original 737 flight characteristics on the 737 Max, it was selling argument for the 737 Max, airlines buying it could have a « new » plane with state of the art economic engines, without having to pay for re-training their pilots. Not a total success…

maxcan 5y ago

This is a big part of the answer. Usually when you're adding power, its because you want to go up so the last thing you want to happen is for the nose to go down. The higher up the engines are relative to the center of mass the more of a downward pitching moment you'll get. Also, I believe (and I'm very much not sure about this) but the above wing mounts like the Honda Jet can have nasty implications for flutter or some other structural issues if you aren't really careful. Its like the dynamic instability of trying to hold a stick at the bottom vs the top.

galgot 5y ago

Yes, the reason for the engine position on the 737 Max is that newer hi bypass ratio jet engines takes a lot of place. As the original 737 was designed for flying with much smaller diameter P&W JT8D, it stands quite low on the ground with relatively short landing gear . Thus, with newer and newer hi bypass engines , the engine pods had to be moved further up and front of the wing, which in turn changed the flight characteristics compare to the older versions. With the Max ,enough that it would have required client airlines to have to re-train their pilots on a new 737 flying differently than the original 737 they were trained for. And here enters the infamous MCAS which was designed to keep the original 737 flight characteristics on the 737 Max, it was selling argument for the 737 Max, airlines buying it could have a « new » plane with state of the art economic engines, without having to pay for re-training their pilots. Not a total success…