What is this propeller device on the CR.32?
X-Ray only tells that there is a fuel tank in this casing.
So what is this??
“Chewie, lock in auxiliary power!” ??
Engine module for when the upper wing separates to fight independently?
Wind turbine to generate electricity? But why not take that from the engine itself??
Wind speed measuring device to get the airspeed? But, located in the prop wash… this would indicate totally falsely??
Usually a wind driven dynamo.
Not engine driven because the engine wasn’t fitted with one - remember this comes from the 1920’s essentially, many engines had design origins from a time when aircraft didn’t actually have any electrical systems at all!!
Putting another fitting on the engine would make it heavier and bulkier (need to make changes to crankcase or gearbox castings to do so), so it was easier to put a small propeller in the airflow.
Lots of a/c from the 1920’s and 30’s have them.
Notably the Me-163 rocket has one right at the front for the same reason, because they couldn’t fit a generator or alternator to a rocket engine!! :)
In some cases it might be for other purposes, eg to provide hydraulic power - eg the German Argus engine used on many smaller a/c has one fitted to the front of each propeller that provides hydraulic power to the pitch change mechanism - it is the cone with the vanes in this picture:
