C47 engine start, counting the blades?

[DogTailRed2]

The C47 engine start proceedure contains, among other things, engaging the starter and "counting the blades" ?
So why are we counting the blades and how many?

[adysmith]

You want to check that the engine has gone through, I can't recall if it is one complete revolution (three blades) or one full four stroke cycle for each cylinder (six blades).

This is to ensure that you do not get a hydraulic lock with oil in any cylinder with another cylinder(s) actually under power; which was a very efficient way of bending con rods

[Marijn]

This might be of interest to you:

http://www.douglasdc3.com/prop/prop.htm

[Airspeed]

Thank you Marijn
I'd seen footage of air crews hand turning on their way onto their aircraft, did not know about the rope pull start option.
Another fact learned today.

[Tomliner]

Thanks Marijn. That was really interesting. I frequently use the MAAM SIM DC3/C47 etc in FS9. Unfortunately they don’t seem to have provided a rope pull through option! EricT