Paddle wheels

[John S]

Is there any particular reason for some wheels having 7 floats or maybe 9? Medway Queen has 7, John H Amos looks the same as does Eppleton Hall but not quite sure about that. Most model ones I have seen have 8 or some other number that divides easily into 360 degrees. The Westbury paddles have 8 floats while K N Harris for his inverted twin cylinder oscillating engines calls for 9. I am not thinking of the large wheels fitted in US or Great Eastern nor stern wheelers so maybe someone can come up with a reason. the best I can think of is 7 do not interfere with each other when entering or leaving the water so result in a more efficient wheel but that may just be wishful thinking.
John.

[derekwarner_decoy]

Welcome John......paddlewheels!...that's a rather large subject on design  ... however we must have some consideration for the 200 years these have edvolved from

1. installed power and output shaft speed?
2. size & type of vessel?
3. number/size & depth of blade immersion
4. feathering or fixed?
5. available width...etc, etc?

Our forefather Engineers had some excellent skills in geomerty, so I discount any issue with any number being divisable into the 360 degrees

You would need if possible to read & understand the engineering calculations for each of the wheel sets associated for the Proprietry manufacturer/designers you mention, many of which are not available

Derek   

[Spankbucket]

Radial aero engines always have an odd number of cylinders. I think it is for the same reason. Unfortunately I have forgotten the reason since I read up on it some years ago.

[Bierjunge]

The odd cylinder number of radial engines doesn't, of course, have anything to do with paddle wheels.
There's only one common crank pin for all cylinders. In a 4-stroke-engine, cylinders ignite every two revolutions. So as the crank passes all cylinders in a row, one cylinder ignites, one doesn't, one ignites, one doesn't and so on. After two revolutions, everything repeats. This would not be possible for an even number.

Moritz

[Spankbucket]

Thanks Moritz for the correct explanation which makes complete sense.

Perhaps this alternating cycle gets replicated in a steam paddler?