A couple points -

IF Joe tweaks his stab/elevators and it fixes his KE problem, the tweak will result in zero adverse trim changes and will not compromise a single maneuver up to and including FAI. If the tweak doesn't fix the problem, them something else is the culprit (again, I don't advise the tweak until all other geometric / trim consideration are addressed first).

I don't fly around trim problems.....bad use of my limited brain power I'd have never cut a wing in half 4 times so I could fly around a roll coupling issue or any other problematic trim setups. I never use a Pmix or aerodynamic device that does not make the plane fly better - and by better I mean the same quality maneuver can be replicated with reduced pilot workload. And the Pmix is the last resort.

I don't remember the year (Brian may remember), but some number of years ago, I flew with Bryan at a practice field at the NATS (I think it was Kokomo), and I got a flight on his plane. Trim condition on the plane was superb - straight KE, straight verticals, no bad behavior. Except.....I found the plane very touchy.....it was for me very tailheavy (but not unlike many setups I have and continue to see). I know since that time, Bryan has been setting up his planes with a more forward CG, and while I have not flown one of his planes recently, I am sure the forward CG setup is at least as good or better than the tailheavy setup (otherwise the tailheavy setup would still be used).

In 2008, I was extremely happen with the trim on my Bravo, and it had zero aerodynamic devices on it. It began sprouting aerodevices when the schedules changed and increased the demand on the planes. I tested many aerodevices to get the performance improvements I wanted, and if I had the time, I'd build an entirely new plane, but I don't have that time....in part because I spend it practicing instead. I've helped trimmed many different designs using my methods and found that the same size does not fit all...the idea that one trim technique or process is equally suited for all designs is nonsense......and suggesting a particular design is flawed or junk if it doesn't respond to a particular trim process is also nonsense......different planes have different strengths / weaknessess which are very often the deliberate choice of the designer based on what they choose to prioritize. And pilots can choose to fly designs which are best suited to their style / strengths / weaknesses. I have spent a limited time trimming Hebert designs....quite simply they have never been flown in the Northeast US in substantial numbers, so I've not spent much time trimming them.

So far as the spiral airflow theory......how much effect spiral airflow has on a design can and certainly does vary with the design. But...having flown F3P foamies and F3A planes with single and Contra setups, spiral airflow is absolutely real. I would never suggest there is only one way to design or trim for it.

Again, I took a pair of identical Bravos and changed 1 to a Contra. In steady state low beta KE flight (thus negating PFactor and gyroscopic precession), the single prop needs the tweak in the stab to KE straight while the Contra needs no tweak. On the Bravo (and many other designs), I've yet to experience a negative effect from tweaking the stab (to the extent needed to fix the KE assymetry). From my experience with the Bravos, I find it very unlikely that a single design plane will fly equally well with a single prop and Contra using the same trim setup. It is possible that such a design exists now, or may exists in the future, but I find that possibility unlikely.

Hey Tony!!! Looks like you, Matt, Bryan, and I all agree about an aft CG being BAD!!!!

Regards,