Salute!
@washoutt...... from way early on the thread, and I did not opine.
A fully FBW plane basically comes in two varieties:
- hydraulic lines run to actuators that operate/move the control surfaces. That;s elevators, ailerons, rudders, spoilers and high lift devices. The actuators could be commanded/controlled by remote terminals on a digital data bus or directly controlled by wires carrying signals from a central box.
- electrical commands are executed at the control surfaces with zero hydraulic lines from the aircraft. In other words, volts and amps move things. The F-35 is one such beast( no kidding, electric pumps and such at the actuators, with no hydraulic lines) , and prolly many space payloads use a similar architecture.
The commercial airline folks have never gone to a completely "electric jet" like the Viper, Raptor or Stubbie(F-35). after all, they fly completey different missions and we lies have the nylon let down option if things go bad. So we have seen a variety of flight control systems by the commercial folks that have various degrees of mechanical things, assiciated/ taylored control laws and then specific degradation fault sequences such as we saw in the Airbus ( 447 et al). No commercial system that I have seen goes directly from normal to "direct law".
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I have expressd my concern on several threads about the hybrid systems that mix some FBW concepts, including sftwe and hdwe, with basic hydraulic and cable/pushrod control linkages.
The 737 fiasco is best example to date. A basically good design has had one after another thing added as the aerodynamics of the jet were different after each new engine or tail design or whatever. The best example of a call/hint to start over happened last October.
I completely understand the rationale of the heavy folks developing and fielding new planes. Unlike the military requirements that have a vastly different element of risk, the heavies should have a more robust control system. And it could or should have some basic maechanical aspects if there's computer problems or electrical problems or even structural damage.
My beef is the mix of FBW and actual mechanical architecture has not evolved to an accepted, reliable, understandable state.
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And BTW, for many of the youths here. As with most of the military professionals here, I flew four different jets from 1965 to 1984 that had zero mechanical linkages from my stick or rudder to the control actuators or surfaces, All were irreversible hydraulic lines/actuators with zero aerodynamic feedback to me as I had years before in Luscombs, Champs and Taylorcraft when I really learned how to aviate.
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'nuff philosophy from this old man.
Gums...
Last edited by gums; 26th Feb 2019 at 22:42.
Reason: aded commentary/spelling