I understand that the radiator in the Hind series aircraft had bungee assisted retraction systems and were normally flown in the fully retracted position (or had a locking mechanisim?). If however the radiator was extended or not locked and the aircraft flown inverted (aerobatics, combat) then between the bungees and gravity there would be a very loud noise as the radiator arrived at it’s stops.

These radiators were a honeycomb of copper tubes held in place by lead solder and quite heavy.