A question about spinners for Hastings drivers.
On almost Pratt & Whitney and Wright radials there is only the propeller mechanism which is shrouded, again on Bristol and Alvis. The pictures of the Hastings vary; most have a big spinner that covers most of the first cylinder bank and the Viking and Valetta were similar.
Occasionally pictures show up of them flying with the spinners removed. It could not have been a tropical requirement or all the aircraft in FEAF would have flown without them.
Two reasons for spinners come to my mind. One is to streamline the nacelle and the second is to stop the engine being overcooled. My little experience on American radials; CH57 Mojave; which had little aerodynamic cooling, showed that on the whole the gills were only fully opened in the hover so I wouldn't have thought that overcooling was a problem. On the Hercules was there was a penalty for the lack of finning because of the sleeves?
They look pretty but why did they come along so late in the radial engine era.