Having made the decision to "just fly it" for a while, I couldn't resist a couple of measurements. Empty tank balance at 6.45", full tank (take off) balances at 5.6" and after an 8 minute flight it balances at 6.0." This seems like quite a large range, thus the desire to move the tank to the CG (one of these days). From start of flight to end, I did need to re-trim a couple of clicks for level flight. The other test, from one of the many trimming articles I found, is to trim for level flight at full throttle, fly a distance at full throttle, then cut to idle and see what happens. I did this early in the flight; the plane continued straight and slowly lost altitude. To me, this would indicate that the downthrust is about right.
Comments?