help – 1/250 scale Yamato

[john hutchinson 1Participant @johnhutchinson1]

Hi Stan,

Are your props the same diameter as the originals and also are they a mix of left hand / right hand blades, if that makes sense.

John

[C V E 73Participant @cve73]

HI John I have sent you a private message. Far to much to type hope you make contact.

Stan.

[Richard SimpsonParticipant @richardsimpson88330]

Posted by Malcolm Frary on 27/11/2020 11:24:10:

Cavitation is only likely if the kit props are poor – plastic kit moulded ones can have very thick blades which create more turbulence than drive. Most "cavitation" on models is actually aeration – air being sucked down from the surface. Model battleship props are likely to be far too deep to be affected.

Agreed, I think we tend to abuse the term 'cavitation' nowadays, as we seem to with many traditional definitions. Strictly speaking cavitation relates to the creation of vapour pockets in a liquid as a result of a sudden drop in pressure as you might find in a propeller that is either poorly designed or rotating far too quickly. Nowadays the expression tends to also be used to refer to a propeller that is spinning so fast that it is unable to 'grip' the water and so spins around in a turbulent void creating little thrust. I have heard that effect referred to as a 'stalled' propeller as well.

When I used to do inspection dives on ship's hulls it could be interesting to see the pattern of cavitation erosion around the propeller surfaces, caused by the cavitation bubbles impinging on the surface and eroding it away.

You are more likely of course to find cavitation erosion in a centrifugal pump and is the main reason why you should never control a centrifugal pump output by throttling in the suction valve. I have seen large sea water pump phosphor bronze impellers come out looking like a piece of lace as a result of extreme cavitation erosion.

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