Conducted 11/22/2012 –
We returned to the hangar yesterday evening to conduct our usual postflight inspection of the plane, and to get it reballasted and fuel for a possible flight in the morning if the weather held out long enough. This Thanksgiving we had to give a bit of thanks to mother nature for keeping the winds and clouds at bay long enough for us to sneak in one more flight before a snow storm. John’s report to the cozy list is below:
“Sunrise was to be 7:23am, so we were at the airport at 7am to get the plane preflighted and pushed out. At 7:25 I was wheels up from runway 13. Shortly after I snapped the attached pic, and was reminded that a simple sunrise is reason enough for thanks.
I had ballasted the plane for a cg of 100.5″, 1″ aft from my mid CG stall and stability test. I figured I’ll make smaller changes the closer I get to 102″. I’m sure you can already guess, but testing went just fine.
First I wanted to do an ASI calibration at 60Kts. I had done 80-140 previously, but wanted to see if there was any anomalous error at 60 near the canard stall speeds. After flying my 4 legs, the spreadsheet informed me of my big whopping 8/10ths of a knot error. I would be willing to bet the error was less in instrumentation and more in my ability to perfectly hold 60Kts. But at least I knew I was dealing with accurate reading this low as well.
Next the stability tests confirmed what Marc had already reminded me, the plane is more stable at forward cg, not less. With the CG now at 100.5 it took 3 full pitch oscillations to return to trimmed airspeed. I didn’t notice any difference in roll stability, and maybe just a bit more ‘jumpiness’ in the yaw stability. It’s tough to say for sure because the yaw response is very fast. When I release the rudder pedal, the plane straightens out very smartly, so it may have shot past center ever so slightly, but I can’t be certain until I review the video.
Next the stall testing showed straight ahead stalls at this CG to be about 56, maybe 57Kts. Hard for me to be more precise with my ASI graduations (5Kts), but I would lean toward 56Kts. The bobbing was faster, but the amplitude seemed smaller. Perhaps it’s just because it didn’t drop as far, and it more difficult to judge the deck angle. On my initial approach to straight ahead stall my eyes are glued to the ASI so it could be just my lack of photographic or videographic memory…hence the reason for the in flight videos. Accelerated stalls did seem to have a more pronounced amplitude. I was glad I waited till after the flight for breakfast. the 60deg accelerated stall would have had me opening the canopy in flight (just kidding) for an overboard dump if there would have been food in my stomach. I don’t usually get airsick, but I like to do at least a few oscillations each direction at each bank angle to make sure I can note if there is any roll stability issue during the stall. At the 45 and 60 deg bank angles, that’s a lot of spinning!
After stall testing was complete I hurried back down to beat what was forecasted to be 6000′ ceilings and winds at 20Kts gusting 29Kts. Another 1.5hours on the bird, and my fears of stall testing are finally subsiding a bit.”
