It sounds more extreme than it is—“forced exercise” is simply tandem riding in which patients are required to pedal 80-90 rpm.
Meanwhile, they kept up a jabber that sounded like a 33-1/3 rpm record being played 78 rpm.
Portions of the turbine also volitized; idling at eight thousand rpm, it became unstable.
Later tests would put the rim through check-out tests to as high as 1.59 gee, but "normal" operation had been fixed at two rpm.
The out-of-balance fan, turning at close to 35,000 rpm, flew to pieces and the air cushion vanished.
1906, initialism from revolutions per minute.
rpm or r.p.m.
revolutions per minute
rotation per minute