Basic control law, et al
TNX for nice words, Aura. And A33Z seems to homing in on the concept I advocate - to some extent.
There is absolutely no reason to diminish the capabilities of a FBW system in the "basic" law.
- Nz and alpha for pitch commands, roll rate command and HAL stops when control pressure released, with some body rates and control surface aero characteristics and servo-actuator limits and.... all thrown into the mix. This is the same as all the direct hydraulic systems we have had since the F-86 and some British lites way back in the 50's. In those days, the hydraulic pressures were physically modified between the control stick/wheel/yoke and the final control surface movement ( rate and deflection).
- In the most basic "law", I have a jet that flies like all jets, but more precise bank control and a known pitch command if I release the stick/yoke in any axis. For a heavy, I like the 'bus implementation, as it's biased about a one gee command. My Viper could be trimmed for a gee at neutral stick ( minus 2 or so and plus 3.5 gee), but this doesn't seem practical for a heavy.
- All the bank angle and pitch angle stuff seems more like an autopilot function, and is all well and good until things break. What I want and need (as do all the SLF's paying to have a safe, comfortable ride), is something to hang my hat on.
With all the discussion about the air data being unreliable or completely FUBAR, I can't understand the lack of a simple "standby gains" feature that HAL uses for "q" and total pressure. Ours was about 140 knots gear down and 300 knots gear up. So yeah, if flying at the speed of stink the jet was twitchy ( technical term we lite jocks use), and if slow the jet was sluggish. But we still had alpha limits, rate limits, gee limits, and the beat goes on. NOBODY COMPLAINED. We never lost a jet if the air data went south except for the pelican strike that took away AoA, pitot-static and had damage to the actual FLCS computers just in front of our feet. Big deal.
In other words, a basic loss of the air data is no big deal, and we can throw out all the 'protections" and simply have a basic, well-designed jet to fly until we get all the right inputs back in the green. I am confident that even a newbie flight officer could fly the jet at almost any flight condition if this were the case. I would not pay my fare if I didn't believe this.
My concern of the accelerometer and rate inputs to HAL is valid, IMHO. They should be embedded in the basic FLCS, and should be the "core" of the system.