Comment by jakelarkin | Hacker News Reader

Comment by jakelarkin | Hacker News Reader

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"the plane should never have gotten the green light to fly."

this is an overstatement. airframe fuel efficiency is a undoubtable good thing vis a vis climate change, costs, etc. Obviously they've reached a point were the aerodynamic profile of a modern, efficient airframe is difficult to control via manual pilot input alone in some scenarios. This was the case for stealth technology with fighter/bomber designs.. the B2 for example has no vertical stabilizer and would not be controllable at all without fly-by-wire. Of course pilots will lament complexity and the loss of manual input. Regardless, the FAA wanted MCAS in the 737Max. Augmenting human input in the face of instrument failure and possible human failure is an extremely hard problem and uncharted territory for the industry. Doesn't at all mean its a not a worthy goal or that the designers or regulators had ill intent or negligence.

That's not really the problem with the B737 MAX though. It's not inherently unstable like e.g. a fighter. The issue is that they had to fit the engines in front of the wings, and this will create a significant pitch-up if thrust is added abruptly, e.g. in a go-around.

To counteract this they introduced the MCAS system. They would not have needed this if they hadn't "retrofitted" big engines on an old airplane design, but instead started from scratch. The B737 MAX is not really a modern aircraft, but a heavily modded old design.

That's interesting to know, I think the 737 Max looks very kitbash because of the way the engines dangle in front of the wings.

The problem here isn't that a 737 MAX style design is inherently unstable. The issue is that the larger engines really needed longer landing gear and other significant airframe changes, but due to demands from Southwest that it remain within type-certification for the 737 (to avoid the costs of pilot retraining) some unfortunate compromises were made that affected the aircraft's behavior.

You can design an aircraft just like this that won't have those characteristics. You'll just need to pay to get it certified and then airlines will have to pay to train their pilots. Instead, Southwest wanted the band-aid fix, and Boeing obliged them.

An aerodynamically sound redesign to accommodate the high bypass engines would have been just as fuel efficient as the version with confusing software band-aids.

If it is cheaper to invent something like MCAS than to properly adapt the airframe, then maybe the processes that would be used for the latter are ripe for some efficiency optimization.

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