Pratt & Whitney Double Wasp

[cardboard_killer]

I saw a reference to P-35As, which used a P&W R-1830-45 engine, requiring "antifreeze". I am not a gear head, but always thought the air cooled radials did not require coolant. Maybe it was for the supercharger (which I don't even know if the P-35A had)?

[Supercharger]

In some cases they used a kind of antifreeze for the carburetor and for the airscrew as well. And yes the R-1830 Twin Wasp was equipped with different types of superchargers. From single stage single speed up to two stage two speed. Blower drive gear ratio was 7.15:1 in case of an later civil version called C3.

Edited July 16, 2021 by Supercharger

[cardboard_killer]

2 hours ago, Supercharger said:

And yes the R-1830 Twin Wasp was equipped with different types of superchargers.

 

Understood, but I was questioning whether the P-35A's R-1830-45 engine had one installed.

[Supercharger]

That's for sure, because an centrifugal impeller is an design demand for an powerful radial engine like the Twin Wasp. Otherwise the engine will be suffering from uneven fuel distribution. This is why every aircraft radial engine has an supercharger even with very low boost pressure required, you need to ensure evenly fuel and air distribution to every single cylinder.