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-   -   Hard or Soft Limit Protections? (https://www.airlinepilotforums.com/technical/72849-hard-soft-limit-protections.html)

FastDEW 02-02-2013 10:20 PM

Hard or Soft Limit Protections?
 
There was a thread this week about preference of Yolk vs Side Stick - which really comes down to Boeing and Airbus discussion. It got me thinking -

Which do you all prefer with regards to Protections in the FBW system? The "yolk/Boeing" system uses soft protections with limits that can be over ridden by the pilot. The "side stick/Airbus" uses hard limits which are firm and not (in normal law) designed to be superceeded by the pilot. Which is preferred? This seems like a more important or at least equally important discussion to the differences regarding comfort of the two systems.

Discuss ---

ForeverFO 02-03-2013 04:14 AM

This will (undoubtedly) bring up scads of opinions, but the only ones I'd really listen to would be those who have flown both, extensively.

Since I am Boeing-only, I'd say I like knowing that the Boeing is just a big airplane, and it'll let me do what I want, albeit with a lot of squawking and/or some yoke force.

UAL T38 Phlyer 02-03-2013 05:00 AM

Chicken or Egg?
 
Yolk: yellow center of an egg.

Yoke: a control-wheel for an aircraft. ;)

I've flown both. The pro-Boeing crowd often cites the ability to exceed hard-limits in emergency circumstances, such as an evasive pull-up for terrain or other aircraft. I've read, but can not confirm, that Airbus did a test for just that in the sim, by comparing the scenario in both a Boeing and Bus.

According to the story, that while the Boeing guys sometimes exceeded g/bank limits, it took them longer to achieve them. The Bus subjects could yank the stick to the limit, and achieved maximum g/bank earlier.

Result? The Bus survived more often.

I went through 777 training in 2002 but did not fly the aircraft due to being bumped-downward to the A-320. If I recall correctly, the FBW of the 777 is not significantly different from the A-320 in regards to g and bank limits. I'm certain it can't be rolled past a specific bank, but I'm less certain about g-protection.

Personally, I like the Bus, and have no problem with its control-laws.

FastDEW 02-03-2013 01:34 PM


Originally Posted by UAL T38 Phlyer (Post 1345051)
Yolk: yellow center of an egg.

Yoke: a control-wheel for an aircraft. ;)

ROFLMAO. Yes, you are correct. I guess I should have noticed my mistake. But maybe I have been flying Airbus too long and forgot that a "yoke" actually exists. Haha :D

UAL T38 Phlyer 02-03-2013 02:18 PM

With no "yolk," does that make the Bus an "egg-beater?"

Ever since Tex Johnston rolled the 707 prototype, a Boeing big-wig (President or CEO, not sure which) has supposedly told the test pilots before the first flight of any new aircraft:

"Don't roll it."

I saw a Youtube clip where the test pilot of the 777 told him "But it can't!"

He said "Just don't roll it."

tomgoodman 02-03-2013 08:25 PM


Originally Posted by UAL T38 Phlyer (Post 1345316)
Ever since Tex Johnston rolled the 707 prototype, a Boeing big-wig (President or CEO, not sure which) has supposedly told the test pilots before the first flight of any new aircraft:

"Don't roll it."

I heard that when the "Boeing big-wig" saw Tex do it and became agitated, a General standing next to him said: "Relax -- I think he just sold your airplane." :cool:


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