Time line got a little whiplash here.
Only the first 77-78 Spitfires had two blade props (wood/fix pitch) and they stopped fitting them in the spring of 1939.
How long it to replace them I don't know.
Being fitted in late spring were the 3 blade 2 pitch propellers, somewhere in the summer and/or fall of 1939 they were fitting the blade constant speed props for testing.
Somewhere around 1/2 of the Spits in Sept 1939 may have had the old two blade props (or less, depends on refit schedule). By the fall of France very few would have had them.
We also have to sure we are looking at the same numbers.
Planes in service can mean planes in operational squadrons or planes in all squadrons ( squadrons that working up with newly issued planes but are not "declared operational" yet and/or OTU squadrons). British had a habit of stockpiling aircraft in depots, so active/operational squadrons could draw replacements from the depots and not have to wait for factory delivery for combat or accident damaged aircraft.
250 in service might have been backed up 50-100 in depot (maybe more) so the front line units could keep up their numbers.
I would really like to see some sort of study on the ability of the Hurricane to soak up damage.
View attachment 699243
What did it get by?
How many times?
(this is actually bomb damage)
A single 20mm hit can take off a lot of fabric. The question is how much of the steel tube structure was damaged?
We have the oft repeated photos of a Spitfire that was wrecked by 3 canon shells. But it got the pilot home (or satellite field) and the pilot could have been flying the next day with one of those depot Spitfires.