Scratch built ribs and outboards

The hole-shot is great!
With the knowledge this is a plus 6 kg model that is very impressive!

Very clear that the exit jet-stream is really fast!
Raw power!
 
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Here we have added a ring to the bottom of the impeller, this stops the blades flexing as much when spinning at 26,000 rpm. I also found another use for it , it can be used to pull the impeller off the shaft

The wear ring has been removed in this photo, that is a close fit to the impeller, a little silicon grease was added to stop them binding, and of course the water keeps them cool, so I don't run it much out of the water.
 
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New bilge pump......this one is a diaphragm type, I wouldn't recommend the peristaltic type now it kept getting stuck. So I got 2 of these on aliexpress for £7 incl post. I drew up and printed the blue mounting bracket, the pump is just a tight push fit, I made it to suit the holes of the old pump. To test I poured some water in the boat , flicked the switch, well impressed , within seconds all the water was pumped out the back, i hope it proves reliable. So cheap i may order some more for my two new boats. The other rib is also going to get one too and that has a radio switch.
 
Centrifugal jet-outboard! Another home made and designed outboard!

Love the slomo footage!
Just like a real scale boat. Even the sound matches!
 
Laatst bewerkt:
Thanks Michiel, really pleased you talked me into doing it now. I have ordered some one way valves to keep the pump primed. On the blue rib the pump is much lower down so seems not to suffer the same way.
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Testing this impeller today , back to 30mm pitch, but streamlined center for better water flow.
 
My gut feeling says there is something to catch in the impeller design.
Looking at the true scale jet-outboards from Yamaha, the shape is a bit different concerning the angle of the blade at the entrance/inlet.

I wish I had the SimScale option still for CFD research, but at the moment I still have not found an alternative.
Yes, OpenFoam is an open source free CFD platform. SimScale is using that engine for their CFD solution.

And there you have it: SimScale is providing a very user friendly user interface. OpenFoam is very academic. I need to invest a ton more of time to accomplish the same results :(


Take a look at the impeller from our German friend.
Maybe there is something to try!
 
This one to try next, at the other end of the scale, only 27mm diameter. Maybe somewhere inbetween.
 

Bijlagen

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Can we break the 20mph barrier? Yes....hit 21mph with the 33mm diameter impeller.
The 27mm was no good, only 14mph.
So next up is a 32mm with no ring to get in the way, printed in 2 halves and glued together. This produces a better finish and is easy to clean because it can be held in a vice on the flat edge.
I think we can smash the 21mph barrier now.
 
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