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Rfv-sense: "Of a rotating part of a machine, to become disengaged and rotate freely". Is this distinct from the other rotational sense? --EncycloPetey 06:33, 16 May 2010 (UTC)

I believe this sense is intended in the sense of a cogwheel in a machine coming loose from the mechanism and being sent off spinning in a random direction. Think for example of a helicopter blade that becomes detached from the helicopter and spins into the air for a while before crashing down into something. That's certainly not the 'normal' sense of a windmill's operation... —CodeCat 09:36, 16 May 2010 (UTC)
This is quite common in aviation to describe a propeller disengaging and spinning in the airstream. I believe most aircraft have a system to prevent it, as the windmilling blade can cause vibration and drag.--Dmol 10:03, 16 May 2010 (UTC)
For one thing, the usage examples show that the first sense is transitive and the second intransitive. I've heard the second sense more than the first. DCDuring TALK 11:02, 16 May 2010 (UTC)
I'm not sure that "to become disengaged" is necessarily part of the definition. Again in aviation, it's common to describe the rotation of a turbine engine's compressor fan as windmilling when the movement is being caused solely by the surrounding air stream (e.g. surface wind when the aircraft is parked on the ground, or the movement of the aircraft through the air with an engine shut down in flight) rather than by the gas generated by fuel combustion – but nothing is "disengaged". -- NixonB 18:14, 18 May 2010 (UTC)
There's quite a difference between a turbine blade and a propleller. A prop must disengage to be spun in that manner, a turbine fan does not.--Dmol 23:10, 9 October 2010 (UTC)
Cited. - -sche (discuss) 18:53, 9 May 2011 (UTC)

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