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Which means "Evil Twin". Lets see your projects where you change boring into fun or create the fun from scratch.
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 Post subject: Re: Dyno
PostPosted: Wed Mar 13, 2019 8:46 am 
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One thing I'm not seeing, at least with the current designs, is how the water exits the housing. It's an important consideration for good control speed.


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 Post subject: Re: Dyno
PostPosted: Wed Mar 13, 2019 9:27 am 
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mekilljoydammit wrote:
One thing I'm not seeing, at least with the current designs, is how the water exits the housing. It's an important consideration for good control speed.

right, I didn't add that yet but the more the general design looks like a Stuska brake, the more the fill and drain will look Stuska I guess.


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 Post subject: Re: Dyno
PostPosted: Wed Mar 13, 2019 3:46 pm 
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Here's V3. Right now its a 2" thick rotor but it could go to probably 3", just increase the rib thicknesses....I'll hold that though prending some basic dimensions from the Stuska rotor..... then time to decide whether to continue on this path or do a toroidal type.....


Attachments:
Rotor V3 1.JPG
Rotor V3 1.JPG [ 59.43 KiB | Viewed 80 times ]
Rotor V3 2.JPG
Rotor V3 2.JPG [ 92.26 KiB | Viewed 80 times ]
Housing V3 2.JPG
Housing V3 2.JPG [ 25.37 KiB | Viewed 80 times ]
Housing V3 1.JPG
Housing V3 1.JPG [ 57.3 KiB | Viewed 80 times ]
Assembly V3 1.JPG
Assembly V3 1.JPG [ 70.75 KiB | Viewed 80 times ]
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 Post subject: Re: Dyno
PostPosted: Wed Mar 13, 2019 6:23 pm 
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Driving home happy the airbag and seat belt lights went off on my car it occurred to me that I should probably print a couple brake options and test with an electric motor and actually know which designs work.


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 Post subject: Re: Dyno
PostPosted: Fri Mar 15, 2019 8:07 am 
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24 hours later and I'm still liking the test a printed version idea....I'll need to trim them to control clearances but that's quick. I'm thinking make a Stuskaish, dynomiteish and the last 2 housing I posted with the last rotor so 4 versions to print and test. I'm thinking little DC motor that spins 15-20k, higher is I can find it cheap since small rotors will do very little at low RPM, then 2-3" rotors....I could probably go to 4".

Thinking about test rotor size yesterday I got looking more closely at the dynomite charts.....they confuse me.
https://www.dynomitedynamometer.com/abs ... charts.htm

The 13" and twin 13" make perfect sense. The rotor is going to be about the same OD at the Stuska and they have similar charts rpm wise. That is as it should be. but then the 11 (in 13" housing) has the same shape rpm wise.....so it must have the same rotor OD and isn't 11 anything, but maybe is a hp equivalent to their old 11" product. The 9" make sense....but the 7" peaks at a lower not higher rpm....all I can think is they were targeting a hP number and restricted water flow or volume which truncated the curve. Then comparing the 19 to the 13....peaks at nearly identical rpm which again is impossible which caused me to notice the 13" curve looks unnatural and truncated.....hmmmmm....that doesn't help me pick a test unit OD


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 Post subject: Re: Dyno
PostPosted: Fri Mar 15, 2019 9:06 am 
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35k rpm 12v motors for kids riding toys are cheap, $14.....that seems about right. A 10pack of 5mm seal bearings are $10...so 5 water brakes or 4 plus a spare set.


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 Post subject: Re: Dyno
PostPosted: Fri Mar 15, 2019 2:06 pm 
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Here are the 3 rotors I think I want to test. I'm leaning toward 75mm with a 5mm shaft. I'll probably setup up the simple 1st and see what it does....if its too much for the motor I can just turn it down and reprint the housing. Then I'll do 2 or 3 housing options that all these rotors should fit and we'll see what we'll see. There is still some risk that the results don't really scale because the water viscosity just acts different on small parts than big....but it should at least tell me if I'm thinking all wrong and I should copy someone who knows better.

edit - forgot the dynomite style....I'll need to draw that up too.

A simple vaned rotor
Attachment:
Simple Capture.JPG
Simple Capture.JPG [ 92.05 KiB | Viewed 51 times ]


A kind of Stuska like thing
Attachment:
Stuska Capture.JPG
Stuska Capture.JPG [ 79.03 KiB | Viewed 51 times ]


A fancier vaned
Attachment:
V3 Capture.JPG
V3 Capture.JPG [ 91.39 KiB | Viewed 51 times ]


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 Post subject: Re: Dyno
PostPosted: Tue Mar 19, 2019 7:36 pm 
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Incidentally, Stuska rotor is about 12" diameter, 2.5" thick with the pockets both on the stator and rotor about 1" deep. Tape measure measurements so not hugely precise but pretty close.


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 Post subject: Re: Dyno
PostPosted: Tue Mar 19, 2019 7:38 pm 
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mekilljoydammit wrote:
Incidentally, Stuska rotor is about 12" diameter, 2.5" thick with the pockets both on the stator and rotor about 1" deep. Tape measure measurements so not hugely precise but pretty close.


Thanks.....very close to what I was guessing


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