Why would photon pressure be needed to keep ParkinsonSAT Spinning? explains that it was equipped with surfaces that resulted in a sunlight-induced torque which have
...succeeded in keeping the satellite spinning at a rate of several RPM for years.
and this answer is thorough and suggests that the drag torque would counter the solar photon pressure induced torque at 80 RPM.
This would of course vary dramatically with solar activity; in LEO atmospheric density can vary of order a factor of ten or more, depending on altitude.
Question: What's the fastest that ParkinsonSat spun? Did it vary with solar activity? It's an amateur radio satellite named
Naval Academy OSCAR 84 so presumably had basic telemetry and a lot of people listening to it, was the rotation rate available, and if so is there record of it?