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Author Topic: Water Jet experiment and Jet boat build  (Read 21690 times)

Mad_Mike

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Re: Water Jet experiment and Jet boat build
« Reply #75 on: May 05, 2012, 10:11:50 PM »

its been a long time since Ive done an update, i haven't really had a lot to say because the progress has been backwards and forwards. 3 motors and 2 esc's later Ive seem to have got some kind of success that doesn't result in smoke :embarrassed:. Ive now got running a 1900kv 2830 outrunner on 3s spinning a reduced diameter 26mm impeller with lower profile blades. Anyway enough waffling:

http://www.youtube.com/watch?v=o3ULmAkzpgw

I must apologise for the quality of the video, i was on my own and had to put the camera down and sail the boat in shot. There are some leaks between the motor and the pump casing which ill address later once I'm happy with the motor.

 Its actually surprised me how much power is required to run a centrifugal pump as a method of thrust. I was hoping that the rule of thumb for matching props to motors would be transferable to pump impellers but it seems not, the diameter of the outrunner needs to be larger than the impeller.  The boat was initially pulling 25 to 30 amps on 3s with the old impeller and requiring nearly 340 watts of power. Its a little less now but still around the 300w range, its nowhere near as efficient as a propeller. I hope that the extra torque of a 3530 1700kv Ive got coming will overcome this and hopefully I'll be able to up the impeller diameter again.
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gwa84the2nd

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Re: Water Jet experiment and Jet boat build
« Reply #76 on: May 06, 2012, 03:02:23 AM »

looking good tho matching a camparable sized conventional jet boat for perfomance and manuvarability and concept proven i shall say a pat on the back well deserved  :-))
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Mad_Mike

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Re: Water Jet experiment and Jet boat build
« Reply #77 on: May 06, 2012, 02:44:24 PM »

thanks :-))
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Mad_Mike

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Netleyned

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Re: Water Jet experiment and Jet boat build
« Reply #79 on: May 11, 2012, 05:14:24 PM »

That looks good Mike
Like a waterborne ferret down a rabbit hole.
Plenty of thrust there boyo  :-)) :-))

Ned
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Smooth seas never made skilful sailors
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http://www.cleethorpesmba.co.uk/

Mad_Mike

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Re: Water Jet experiment and Jet boat build
« Reply #80 on: May 17, 2012, 11:57:21 PM »

Im more than satisfied with the thrust i must admit and has turned out better than id hoped. As it was in the vid I could only run the boat for about a minute before the motor started to overheat. I received my 3530 1700kv outrunner the other day and installed it. You can see how it is clearly larger than the older 28mm ones. Im hoping that the increased torque will be sufficient to drive the pump without the motor straining. It better work this time because 4 motors later the build cost has gone way over budget <*<:

 
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