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 Post subject: DT700 thruster 8lbs 19A
PostPosted: Sep 14th, 2017, 3:40 pm 
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Joined: Sep 14th, 2017, 10:22 am
Posts: 3
We have developed a Kort nozzle and now at Amazon and a propeller specifically for the dt700 brushless motor. The design is created in a prop parametric calculation software with the subsequent updating on 3d models. About 50 variants were made until we reached the level of efficiency close to Blue Robotics T200.
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Specifications:
______________________________________
Tested forward/reverce thrust at 12V
1A - 0,5/0,5 kg (0.5/0.5 lbs)
2A - 1,0/0,9 kg (2.2/1.98 lbs)
3A - 1,35/1,2 kg (2.98/2.65 lbs)
4A - 1,65/1,5 kg (3.64/3,31 lbs)
5A - 1,9/1,7 kg (4.19/3.75 lbs)
10A - 2,5/2,1 kg (5.51/4.63 lbs)
14A - 3/2,7 kg (6.61/5.95 lbs)
19A - 3,6/3,2 kg (7.94/7.05 lbs)

Efficiency (G/W) Thrust (G/Watts) (lbs/Watts)
at 1A: 41 g/w (0.09 lbs/w)
at 2A: 37 g/w (0.082 lbs/w)
at 3A: 31 g/w (0.068 lbs/w)

As you can see we achieve maximum efficiency at currents of 1-2 amperes, which makes the thruster very convenient
for use on ROVs.
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But as an experiment we also tried these engines even as an underwater arm thrusters. At a current of 15 amperes per motor, the speed is 1.85 mph with a swimmer weight of 166 pounds.
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We seldom use them at 20A cause big current means very short battery run time.
If you will use them at high power you should prepare DT700 for it. Our test show this two small screws can not keep the motor from turning at maximum load. Even if you screw them hard they cannot make a good hole. This can lead to a break in the wires and damage to the motor.
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I recommend you to drill a sink:
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Although most brushless motors can work in water, it is recommended to make some modifications (even included Blue Robotics). Over time (after 100-1000 hours) microscopic damage appears on the wire's protective coating. Leakage of current through these holes can lead to malfunctions in the ESC or RC controllers. Moreover electric current into these holes causes electrochemical corrosion, which leads to a rapid destruction of the wires (after 10-100 hours). To prevent this we should impregnate the wires with epoxy. The engine will operate underwater with increased power (5-10 times the nominal!), so it is necessary to ensure a good heat dissipation. To do this, choose an epoxy with a high thermal conductivity.
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Forward and back thrust is almost the same. In the event of a breakdown of the propeller it is very easy to replace it even underwater.
Our robot has made more than a hundred dives with these thrusters and they have proven themselves very well. We use batteries on board and thanks to a small current consumption our robot works 6-8 hours continuously without changing the batteries.


Last edited by ROV_thrusters on Dec 6th, 2017, 5:04 am, edited 1 time in total.

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PostPosted: Sep 15th, 2017, 2:42 am 
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Joined: Oct 1st, 2013, 7:18 am
Posts: 76
Motors look great and the performance is good, a lot of work and effort and a good result. :)

Are you planning on selling thee or making the designs available?


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PostPosted: Sep 15th, 2017, 4:22 am 
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Joined: Sep 14th, 2017, 10:22 am
Posts: 3
Oldsirhippy wrote:
Are you planning on selling thee or making the designs available?


We worked on the design for a year and it was really difficult to reach that thrust. Perhaps we can do
something new and then publish the file of the first model, but for now we would like to get at least a small return from it. I hope that the amount requested is fair enough, given that this is our design and our work. But we can send this Kort nozzle for free to someone who made and published an instructable with our motor.


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PostPosted: Sep 19th, 2017, 9:20 pm 
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Joined: Nov 8th, 2010, 10:25 pm
Posts: 528
Location: Connecticut
Oldsirhippy wrote:
Are you planning on selling thee or making the designs available?


I think you just missed the link in his first post... (click where it says Kort Nozzle in blue) he is selling them on eBay for $35. (which seems reasonable for the amount of times it take to 3D print one.)

-Steve


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PostPosted: Sep 24th, 2017, 2:47 pm 
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Joined: Sep 14th, 2017, 10:22 am
Posts: 3
Previously, we tested it in a 300-liter bath and strong turbulence prevented us from obtaining stable and accurate data. Now we did a test on the lake and got a higher thrust value. Upto 4.78 kg (10.5 lbs) (46.5 N) at 12V 25A.
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