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Author Topic: Paddle wheels  (Read 201 times)

Offline John S

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  • Posts: 5
Paddle wheels
« on: July 28, 2020, 06:20:55 AM »
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.

Offline derekwarner_decoy

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  • Wollongong - Australia
Re: Paddle wheels
« Reply #1 on: July 28, 2020, 08:24:32 AM »
Welcome John......paddlewheels!...that's a rather large subject on design  :breakcomp ... 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 :whistle 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   :beer


« Last Edit: July 28, 2020, 08:29:12 AM by derekwarner_decoy »
Derek Warner

Honorary Secretary [Retired]
Illawarra Live Steamers Co-op
Australia
www.ils.org.au

Offline Spankbucket

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Re: Paddle wheels
« Reply #2 on: July 28, 2020, 04:36:29 PM »
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.

Offline Bierjunge

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Re: Paddle wheels
« Reply #3 on: July 29, 2020, 02:49:18 PM »
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

Offline Spankbucket

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Re: Paddle wheels
« Reply #4 on: July 29, 2020, 04:25:30 PM »
Thanks Moritz for the correct explanation which makes complete sense.

Perhaps this alternating cycle gets replicated in a steam paddler?

 

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