Saturday I did some maintenance on the aircraft, then got a short flight off in the afternoon. I had hoped to do some more testing of an experimental technique to determine stall speed using GPS data, but I didn't get airborne early enough in the day. We had an overcast ceiling by the time I finished the maintenance, and it was bumpy below the cloud, so there was no point wasting time doing the tests, as I knew that the data quality would be poor. Maybe next weekend.