Originally Posted by cmac2012

Interesting stuff. I always thought it was a cool looking plane but never read much about it. Turns out it was the only fighter built during the entire war. Pretty amazing power. Started off with the 1000hp Rolls Royce V12 and later moved up to a 2300hp model. Imagine it was this easy to gain access to your car engine:



I was researching two of the engines - the original power plant was the RR Merlin V12:

https://en.wikipedia.org/wiki/Rolls-Royce_Merlin


Anybody have an idea of what they mean by "...some 50 marks of Merlin were built ..." Maybe it's some industrial quantity term.