Since Howard brought up resumes, I feel compelled to share a bit of mine pertinent to the conversation. I am aware of the level of talent here.
I wasn't the one discussing resumes and I wasn't challenging your assumptions, just trying to find out what you were talking about and maybe offering some suggestions - so I am not sure why you are responding to my post. As I mentioned the other day, conveying information inherently demands asking questions, and those questions are not necessarily challenges or "assertions in the form of a question". I am very happy to discuss it with anyone with an idea - if it is good idea, it doesn't matter where it came from. In any case, I am sure Howard's CV looks better than mine; if nothing else his would be mostly unclassified.
I noted that you could use feed-forward to reduce/eliminate the phase shift inherent in the closed-loop control. You can make it a function of anything you want. My notion from a few years ago would be to use the Z axis acceleration/load factor as either an additional lead element, or, as a feedforward, since it more-or-less measures the drag for you. You would need a band-pass filter to block DC and high frequency noise, but otherwise you could make the feedfoward signal proportional to the absolute value of load factor, the square of the load factor or whatever else you think it should be.
But your first question is still the most critical - what is it that we are trying to control? Paul's observation, I think, relates to excessive/excessively aggressive/excessively nonlinear/out of phase control of the airspeed, where the pitch sensitivity changes rapidly. I think it is the same issue from the "what does 'penetration' mean?" thread. So I might be inclined to start on the premise you are trying to control the body frame X acceleration, that is, the "orbit rate", for lack of a better name for it, and using the Z acceleration as a feedforward and maybe the Y acceleration as a lead element in some sort of a lead-lag control system.
If you are going to control the "orbit rate" which is probably what you want with the "constant angular rate" idea, you *do* have to have some other system to sense it directly, hence, Y acceleration (which at low frequency is proportional to the integral of the X acceleration due to our constraint).
But that is just notional, I am not sure if it is well thought through. The original idea was to use the X acceleration to replicate a Fox 35, which is kind of how this all started.
Brett
p.s. this (and most similar) threads point out an even more basic engineering issue - there are tremendous gaps translating the engineering to the subjective handling qualities that most of us think are the goal. Put another way, we have never defined "good" VS "bad" in an engineering sense, even to first approximation. Paul's example (and my similar example) illustrate that in droves. Paul knew exactly what he changed, and I had at least some idea, but why that improved the cornering performance is at best educated guessing. In Paul's case, very highly educated, but nonetheless, a guess). This is a problem with full-scale aircraft, too. This is the basis of the Cooper-Harper Handling Qualities ratings - a subjective scale used to determine how difficult an airplane is to fly. Of course, the pilot has to be qualified to provide these ratings, and while Paul is probably the best possible evaluator, any of the more experienced/accomplished stunt pilots probably give reasonable evaluations.
But it *is* subjective. I have flown two flights 10 minutes apart, one where the airplane would have rated a 2 (good, negligible deficiencies), and another where it maybe rated a 5 (moderately objectionable). The differences - same airplane, same engine, same conditions, absolutely no trim changes, just altering the oil content of the fuel by 4%. Do the same the next weekend in different conditions, and I might get the same ratings - for exactly the opposite change!
Another example, a 9 (Major Deficiencies, intense pilot compensation required to retain control) to about a 2. Again, the same airplane one minor trim change, and one minor engine setup difference. Several people were witness to me nearly crashing my airplane at the bottom of a triangle in 15 mph wind, same airplane with 1/2 ounce of weight on the tail and a slight pipe length change, it handled 25 with not much problem.
Point being, while I definitely try to figure out what causes these differences, we don't really have any way to translate that into engineering parameters, so it is very difficult to do more than guess at the right answer to your original question, and then try it and see. Electric helps because there is at least some hope of knowing what changed in reasonable engineering terms, why it mattered is still subject to speculation.