Some of my collection

[airwarrior]

Nice link steve nice finds a good mixture of american and british all from same airfield?

[Steve T]

A couple of different bases to be honest, both of which are yielding large quantities of stuff !

And Navyman - Pitch is the displacement a propeller makes in a complete spin of 360° degrees. This means that if we have a propeller of 40” pitch it will advance 40 inches for every complete spin as long as this is made in a solid surface; in a liquid enviroment, the propeller will obviously slide with less displacement.

The pitch concept is not exclusive for propellers, other mechanical devices like screws also use it. For instance, a screw with 10 mm of pitch will advance 10 mm for every complete turn when hit by the screwdriver. In fact, the "screw propeller" concept is literally making reference to that the propeller works exactly like a screw.

A variable-pitch propeller will change its angle of attack thus generating more or less thrust, dependent on conditions. Most propellors are 'automatic' variable pitch......the pilot need do nothing to change the pitch.

Steve T

[navyman]

Thanks Steve,
I'd wondered if it was a different expression used exclusively by the RAF in WW2. Now I see that it's the same as for any screw type.
Thanks again, and good luck with your excellent digging results.
Cheers,
navyman.

[AndyDenmark]

Hi Navyman...Pitch refers to the angle of the propellor blades as they turn. I think you can change it by means of a control so at one setting the prop spins without "biting" into the air much and then you change it to what ever you want according to the situation you are in, ships have variable pirch propellors sometimes..and if you get the setting wrong the prop just thrashes around without moving the ship...someone else may be able to give a better explanation but i think thats the basic idea...Andy