Comparison of the Gloster F.5/34 and the Mitsubishi A6M2. (3 Viewers)

[Admiral Beez]

Yes, I meant the Caproni F.5 images you showed. I suspected they'd be some kind of exhaust stubs, but if one looks at the second picture from slightly the rear of the plane, it seems there's no hole for the exhaust pipe, those blisters seem to smoothly merge into the cowling at the rear?

I think you're right, they're not exhaust ports. Here is the Caproni's Fiat A.74 engine and there is an exhaust manifold just like any other radial.

I now think the bumps around the engine cowl are to make space for the tappets at the top of the push rods. Perhaps these are access panels for easy adjustment? Here are the same bumps on the Macchi C.200.

 

[Shortround6]

Macchi 200, Same engine as the Caproni. Vertical pipe at the junction of the fuselage and wing leading edge is more than likely the exhaust pipe (one of two)
Using rocker box covers to reduce the overall size of the cowling was quite popular during the 30s.

Streamlining was in it's infancy and a lot was was NOT backed up wind tunnel research. The "tear drop or rain drop" school of streamlining was very popular. Blunt front end with gradual taper/s to the rear.

record setting/race winning planes of the mid 30s.
If you are faster than the enemy how does he get behind you?
Actually a lot of ways but people were looking for simple solutions.