I found this interesting article about the use of constant speed propellers by the RAF during the Battle of Britain. It tells the story of a driven Squadron Leader working with industry to convert Fighter Command's force over to CSPs. By early August all Spitfires had CSPs and Hurricanes were converted by the middle of that month, all without taking the planes out of service.

I've never read about this impressive task in the historic writing on the battle.

https://www.smithsonianmag.com/blogs...attle-britain/