Originally yes, in practice no. the following excerpt is from:
http://www.outermarker.co.uk/Article...h/chastise.htm
"The bombs were to be spun by the addition of a Ford V8 engine but this changed such that the hydraulic supply, which normally powered the mid-mounted gun turret that had been removed as part of a weight saving exercise, was used to power a hydraulic motor."
I always assumed it was generated by wind from the airspeed of the aircraft. Wrong again..
Rich.