When I was a kid I did a few laps around a balloon while flying a PA12. That calibrated my brain on what zero airspeed looked like aloft. Upon landing I was offered a ride in an RV4. The pilot saw the PA12 out flying, and did a few laps around it. The two speed differentials matched, and from the back seat of the RV4 it gave a strong illusion that the PA12 was floating along at zero airspeed.
Bryan