2 ms·
To ask the obvious question (aside from "oh wow you worked on the 757 that's so cool tell us everything you legally can?" :D ) which I'm assuming has an obvious
by taneq 3y ago
To ask the obvious question (aside from "oh wow you worked on the 757 that's so cool tell us everything you legally can?" :D ) which I'm assuming has an obvious answer, what happens if one of the four cables (or the elevator itself on that side) simply jams when its elevator is fully actuated in that cable's direction? Isn't this effectively the same situation as one pilot yelling "hail hydra" and going full send on their elevator lever? Either way your control authority (ignoring roll) has gone from [-1, 1] to [0, 1] or variants thereof.
Also something I've always wondered - when designing an airliner what's the boilerplate error rate for a trained human pilot, that you use in "ah yes but what if the pilot does it wrong?" type calculations?
- WalterBright 3y agoThe output is the median of both controls, so the result would be neutral elevator. A lot of effort goes into figuring out what a pilot would naturally do, and to make that work. Much information comes from real life incidents. The engineers and management I worked with were all keenly aware of their responsibility for safety and quality. Nobody wanted to make a mistake that caused an accident. I never heard anyone try to sacrifice safety for money.
- cesarb 3y agoI'm not him (and I'm also not a pilot or aircraft designer), but AFAIK there's also the elevator trim, which uses a separate mechanism and could be used to shift the range of the control authority.
- WalterBright 3y agoThere is a movement limiter on the elevators, that restricts the travel at higher speeds. Going full elevator at high speed will rip the tail off. This is an automatic range limiter, not under pilot control. There is also a stabilizer trim system, which pivots the entire horizontal stabilizer, elevators and all. It's all rather complicated.