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Boeing Engineers Lost Control of the Company

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Re: Boeing Engineers Lost Control of the Company

#91

Post by alumowa »

mltony wrote: post #85

> The new engines were too big to fit in their traditional spot under the wings. To combat the problem, Boeing mounted them forward on the wings. Moving the engine position forward shifted the plane’s center of gravity, which altered the aerodynamics of the aircraft. The position of the new engines pulled the 737 tail down, pushed its nose up, and put it at risk of stalling. Can someone explain to me how this is poss…

Layman here. What I picture in my head is due to the engines being placed higher and more forward on the wing, it will want to rotate nose up when thrust is being produced.

Re: Boeing Engineers Lost Control of the Company

#92

Post by leetrout »

mltony wrote: post #85

> The new engines were too big to fit in their traditional spot under the wings. To combat the problem, Boeing mounted them forward on the wings. Moving the engine position forward shifted the plane’s center of gravity, which altered the aerodynamics of the aircraft. The position of the new engines pulled the 737 tail down, pushed its nose up, and put it at risk of stalling. Can someone explain to me how this is poss…

My armchair physics example would be a balance seesaw and let’s say the left side is the “front”. If you attached a rocket motor (or jet engine) in front of the the CG point would the the thrust push the left side of the seesaw up or down?

I believe the issue is precisely this - the engines were moved (and they are bigger so more powerful perhaps?) forward and the thrust probably pushes the nose up.

Re: Boeing Engineers Lost Control of the Company

#93

Post by NeedMoreTea »

mltony wrote: post #85

> The new engines were too big to fit in their traditional spot under the wings. To combat the problem, Boeing mounted them forward on the wings. Moving the engine position forward shifted the plane’s center of gravity, which altered the aerodynamics of the aircraft. The position of the new engines pulled the 737 tail down, pushed its nose up, and put it at risk of stalling. Can someone explain to me how this is poss…

Not just forward, the 737MAX engines are mounted forward and higher.

If you move CofG forward, and up you move the balance point forward and up, reduce elevator authority, and with similar tail mass now a metre or two further behind the balance point, it will want to sit tail-heavy. So they tried to trim it out, and we are where we are.

Re: Boeing Engineers Lost Control of the Company

#95

Post by [deleted] »

mltony wrote: post #85

> The new engines were too big to fit in their traditional spot under the wings. To combat the problem, Boeing mounted them forward on the wings. Moving the engine position forward shifted the plane’s center of gravity, which altered the aerodynamics of the aircraft. The position of the new engines pulled the 737 tail down, pushed its nose up, and put it at risk of stalling. Can someone explain to me how this is poss…

[deleted]

Re: Boeing Engineers Lost Control of the Company

#96

Post by afterburner »

mltony wrote: post #85

> The new engines were too big to fit in their traditional spot under the wings. To combat the problem, Boeing mounted them forward on the wings. Moving the engine position forward shifted the plane’s center of gravity, which altered the aerodynamics of the aircraft. The position of the new engines pulled the 737 tail down, pushed its nose up, and put it at risk of stalling. Can someone explain to me how this is poss…

Most descriptions of the changes don't go into nearly enough detail. Even pilots have a very abbreviated understanding of everything that's going on, using rules of thumb that gloss over nuance in calculating the stability of an aircraft. Probably a lot of aircraft engineers don't have a full understanding in general unless they're forced to "do the math" on a particular plane.

Making the engine more powerful (as is the case here) means there will likely be more pitching up moment (turning about the aerodynamic centre or AC) due to the position of the engine relative to the AC. Speaking of which, there is an AC, an aerodynamic centre that is separate from the center of gravity. It represents the point about which the plane pitchs up/down when a force is exerted on it.

Not only is the engine more powerful, but the different position it was placed in (forward primarily) would also create a different force about the AC, and change the forces the other parts apply to the plane (by moving the AC and CG).

There might have been more to it but even a few months after really diving into this the details are getting fuzzy... plane stability dynamics can vary greatly.

Re: Boeing Engineers Lost Control of the Company

#97

Post by ajeet_dhaliwal »

sargram01 wrote: post #31

You see this at startups too, middle eng management were actual engineers and as the startup grows career managers creep in and skew the alignment of the engineering departments away from engineering solutions, the “product” they make, to problems they understand instead, political jockeying, manipulation, appeasing the LCD and the next managerial rung above them.

Yes, not unique to boeing, ive seen it in many places.

Re: Boeing Engineers Lost Control of the Company

#98

Post by DuskStar »

lovich wrote: post #90
slededit wrote: post #57

Earlier quoted context omitted.

I'm almost certain "expense of human lives" didn't come up as a factor on any of the merger pitch decks. Frankly its a huge leap to see that a merger of two successful and relatively safe aircraft manufacturers would be intentionally at the expense of human lives.

Why would it have to be intentional? They are pursuing profit. Human lives were ended as a result of their actions in the pursuit of profit. Is that not pursuing profit at the expense of human lives?

If I drive to the store to get milk and end up getting in a fatal accident along the way, am I pursuing milk at the expense of human lives?

Re: Boeing Engineers Lost Control of the Company

#99

Post by starpilot »

nyolfen wrote: post #11
briandear wrote: post #6

Earlier quoted context omitted.

It’s a hyperbolic statement. Boeing employees and engineers also fly on those planes with their families. It isn’t like they are making decisions with the intent of compromising safety.

i have quite the video for you (timestamped, but the whole thing is worth watching): https://youtu.be/rvkEpstd9os?t=2499

That documentary is very naive. This is a good review: https://www.forbes.com/sites/airchive/2014/09/10/review-al-j...

Re: Boeing Engineers Lost Control of the Company

#100

Post by wtallis »

DuskStar wrote: post #98
lovich wrote: post #90

Earlier quoted context omitted.

Why would it have to be intentional? They are pursuing profit. Human lives were ended as a result of their actions in the pursuit of profit. Is that not pursuing profit at the expense of human lives?

If I drive to the store to get milk and end up getting in a fatal accident along the way, am I pursuing milk at the expense of human lives?

If you weren't wearing a seatbelt, then yeah, that's a fair characterization.
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