ARTICULATED PADDLEWHEELS

[fredrosse]

Building Articulated Paddlewheels for the Margaret S. Performance should be improved considerably, although the mechanism will have 72 new pivoting bearings in the water, compared to Zero with the plain wheels I have been using for the last three years.

Geometry here is somewhat different from the traditional articulated wheels, to get some extra speed out of the engine, and thus more power.

[fredrosse]

Went to the junkyard and pulled the rear axels out of a Ford Ranger, and the 14 inch steel rims will be the basis of the paddlewheels. Spent most of the weekend making a jig to align 5/8 inch heavy nuts to the outside of the rim, and welding 36 of them onto the rims. The individual floats ( nine each side) will pivot on bolts that are secured onto these nuts.

Hopefully a dry spray lube will work in the water environment, and all those joints will not make too much noise. Not that noise matters much to me, I'm nearly deaf anyway.

[DetroiTug]

Fred,

Nice design. You might consider sleeve bearings of UHMW (Polyethylene) and for lubrication, White Lithium.

-Ron

[fredrosse]

Thanks Ron. The plan is to run the bolts up tight onto the welded nuts (with lock washer between the bolt head and the nut that is welded to the wheel rim), and another nut will be attached to the movable floats, and will swing back & forth on the screw threads. I have used this configuration on steam engine reciprocating parts of valve gears for years, works well so far, but never with such difficult lubrication conditions.

Would the white lithium grease stick well, and would there be environmental issues with the lube being deposited on the lake if some is thrown off the joints? I was thinking of using some form of "food grade" grease, or teflon tape wrapped onto the threads. There is enough clearance in the screw threads that a wrap of teflon pipe thread tape can be wound onto the male threads, I'm hoping that might work ok, but that might be wishful thinking. UHMW bearings would be ideal, I wonder if I could get UHMW bolts, that would do the job well. Possibly a UHMW coating for the screw threads, even better?

Any info would be appreciated.

[S. Weaver]

Fred, this is a hoot. I have nothing to add, but look forward to the sea trials.

[DetroiTug]

Fred,

I would drill one of those nuts out and run a bolt through to pivot on and use a paddle like this:



-Ron

[DCSmith]

Do you have any estimates as to efficiency, thrust?

[fredrosse]

Ron, thanks for the drawing. The UHMW bearings and long shaft bolts would work well, but I am going to try the screw thread pivots first. I bought 100 Nylon bolts today, 5/8-11 x 1-1/2 long. Only $0.37 each. That should take care of the friction/lubrication problem hopefully. Also getting hard epoxy to coat the threads inside the steel nuts, so no rust I am told.

DCSmith, the numbers I have come up with indicate 44.3 pounds thrust with a boat speed of 6.75 feet per second, wheel speed 75 RPM, effective float velocity 9.34 feet per second. Slip is 28%, propulsive efficiency 61-62% (fresh water). This all hinges on the drag coefficient of the floats, from a handbook. The actual values will be somewhat different, and I have not considered friction in the articulated joints. I will be able to adjust where the articulated connecting rods’ pivot will be located, if it is on the same axis as the main shaft then no joint movement, it would act like a solid non-articulated wheel.

For comparison, the original simple wheels (with flat fiberglass floats, solid bolted to the wheels) indicated these results: 32.5 pounds thrust with a boat speed of 5.75 feet per second, wheel speed 53 RPM, effective float velocity 8.24 feet per second. Slip is 30.4%, propulsive efficiency 52%.

[Oilking]

Fred,
I've long wondered how much energy smaller diameter paddle wheels use pushing water down on entery to then fling it in the air on exit? The tilting bucket should do much to reduce this. It will be interesting to see how much improvement you get.

Seeing the rims gave me an other idea, what if you mounted tires on the rims and attached caster wheels to your rudders? You could have a steam powered amphibion !!?

Dave

[fredrosse]

Oliver Evans made a machine in 1805 that was just that!! Built a few miles from where the Margaret S. is right now, awaiting the new wheels. Oliver's steam powered machine was the first amphibious mechanically powered vehicle. Look up his name on Google.

There is also a kit presently sold to make a paddleboat canoe, with 2 bicycle wheels on the sides of the boat, and a stern steering bicycle wheel. The front wheels double as paddle wheels to propel the boat in the water, and the stern wheel steers the boat. see http://autocanoe.com/