Thruster build

[DavidF]

Ok the verdict is still out, it seems to make pretty good thrust but the amps are probably thru the roof! Wainting on an amp meter and need to rig something up to test the thrust. Trimming the blades a bit might be a solution to reducing the amp draw. It was a fun test though
http://www.youtube.com/watch?v=tP50ajpb ... e=youtu.be

http://www.youtube.com/embed/tP50ajpbWD4

[derelicte]

the bilge blower thing has been done before. if the forum search wasn't so bad you could probably find it. I can't atm.

I really considered using them, but I operate in a saltwater environment.

[derelicte]

here is the big thread on bilge blowers:

viewtopic.php?f=3&t=27

[darrenervine]

Sweet test,....I was expecting that brick to shatter the fish tank at the end there.....

Seems like the thrust is good....I wonder if they would last or if you would end up replacing them....

I like the kort's on them though and the protection

[DavidF]

Ok so I made up the prop adaptor and splashed the 550 motor into the tank, Im really happy with the performance at this point. I still need to make something up to measure the thrust but it feels really good to me. Amp draw was 5.9 to 6 so thats not to bad. The only thing I see as being a problem is that this prop has its blades welded on to the center hub instead of being a cast propeller. I would rather have a cast propeller so I can make copies of them at home. The thiness of the blades on this prop would make that difficult so Ill probably try a couple of other props and see how they perform. Heres the video.....
http://www.youtube.com/watch?v=nroJB3BO ... ature=plcp

And here is the motor im using.
http://www.allelectronics.com/make-a-st ... CHI/1.html

[DavidF]

Decided to try the 540 r/c car motor to see what it would do. "well that sucked" amps were over 10 and it didnt make near the thrust the 555 motor did but hey this is testing right?

[Triton]

Excellent motors!

I wonder why I bought my huge bilge pump motors (sooo heavy and sooo expensive compared to these!)

P.S: Nice way to oxygenate your aquarium. Just don't put any fish in it!

[darrenervine]

That is a sweet set up..

What are the motors in?
Do you have a configuration/set-up documented for that? Rather use that as well then trying figure it out myself..

Thanks

[DavidF]

That is a sweet set up..

What are the motors in?
Do you have a configuration/set-up documented for that? Rather use that as well then trying figure it out myself..

Thanks

Motors aren't mounted in anything, they are just running wet and they are brushed motors. The propeller is a 63 mm 7 blade, not sure what pitch.
I just wanted to do a bit of testing with these motors before I go designing a housing to fit them into. Next step is to see how much thrust they put out, then ill start working on the housing design. Once the housing is done ill try out a few more props to get it dialed in. I'm shooting for 4 to 5 lbs of thrust.

[DavidF]

I did a make shift load test of the motors today, the thrust was considerably less than what I thought it was by the feel of them. I got a measured 1.6 lbs of thrust at 5.9 A @ 15 v. Im still waiting on a digital luggage scale so I can verify the thrust a little better, right now I just stuck a scale up to a piviot to measure it. Not the best way to do it, but I doubt its off by that much and the thrust seems to fall in line with other tests I have seen with bilge pumps. The question is where do I go from here? Be happy with the 1.6 lbs and try a couple of different props and see if I can get it any higher? Or switch to a larger motor and try to hit my goal of 4-5 lbs thrust?
The later would come at a cost of more current draw (more than likely), and I would like to try to avoid using a gear box. Hmm maybe Ill push up the voltage a bit more, to the 20 v rating on the motor, but I think this would take me up to 9-10 amps and the thrust to at best maybe 2 lbs??