draw, thrust, and components

Anything to do with Propulsion.
Lost Bob
Posts: 28
Joined: Oct 7th, 2012, 9:50 pm

Re: draw, thrust, and components

Post by Lost Bob »

Very informative post . My question is, if I am using DT 700 motors with 50 mm Robbe 3-bladed props, I shouldn't use a shroud or any kind of thruster tube set-up ? I might have to change my design if so.
Bubbles
Posts: 72
Joined: Aug 14th, 2013, 6:25 pm

Re: draw, thrust, and components

Post by Bubbles »

Lost Bob wrote:Very informative post . My question is, if I am using DT 700 motors with 50 mm Robbe 3-bladed props, I shouldn't use a shroud or any kind of thruster tube set-up ? I might have to change my design if so.
At my tests Graupner and Robbe propellers perform better without any kind of shroud.Kaplan style propellers perform better with a shroud .You can still use a larger diameter than propeller just for protection.
rossrov
Posts: 383
Joined: Feb 28th, 2013, 5:01 pm
Location: Australia

Re: draw, thrust, and components

Post by rossrov »

Hi hobbydude and Bubbles. Some interesting stuff there with the jet boats. I have gone with large clearance and long ducts. The duct length suits the present ROV layout, that is about all. I tend to agree with the points you make re the clearance. For nozzles to work properly the foil section of the Kort, Rice or other design had to be right. Also, the Kort nozzle (I've been curious about these for a while, and been reading up) is only good for low speeds, like tugboats, and most ROVs I guess. Dunno how good for reverse.
Olegodo: I think you should take a bit more credit. To me, your thruster design looks like a trolling motor (small electric outboard) prop with a Kort nozzle...
hobbydude
Posts: 24
Joined: Nov 18th, 2013, 8:28 pm

Re: draw, thrust, and components

Post by hobbydude »

have no idea how they would go as thrusters for ROV but they do look good, 12v, plastic gearbox, waterproof (looks like it could be beefed up), 15cm prop, cowl
$50 from Aldi. Kids electric bumber boat special today

Image

Image
Lost Bob
Posts: 28
Joined: Oct 7th, 2012, 9:50 pm

Re: draw, thrust, and components

Post by Lost Bob »

@Bubbles
You can still use a larger diameter than propeller just for protection
How much clearance do you think ? Would 1/2 " between prop and tube be enough, i.e. a 3" tube housing a 2" prop ?
Bubbles
Posts: 72
Joined: Aug 14th, 2013, 6:25 pm

Re: draw, thrust, and components

Post by Bubbles »

Lost Bob wrote:@Bubbles
You can still use a larger diameter than propeller just for protection
How much clearance do you think ? Would 1/2 " between prop and tube be enough, i.e. a 3" tube housing a 2" prop ?
I believe 1/2 " is ok for protection .
Bubbles
Posts: 72
Joined: Aug 14th, 2013, 6:25 pm

Re: draw, thrust, and components

Post by Bubbles »

I receive the bluerobotics T100 thrusters and decide to give it a try with X3 control board.
I use a 4S battery and these are the results:
FORWARD
20% power 500gr. 0.42a
40% power 1500gr. 4.65a
50% power 2200gr. 6.7a
60% power 2800gr. 11.7a
80% power 4000gr. 22 a
REVERSE
20% power 170gr. 0.3a
40% power 780gr. 2.22a
50% power 1170gr. 3.84a
60% power 1650gr. 6.46a
80% power 2500gr. 13.84a
I didn't try 100% power since my ESC can handle up to 30a.
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olegodo
Posts: 222
Joined: Aug 30th, 2013, 9:47 am
Location: Bergen, Norway

Re: draw, thrust, and components

Post by olegodo »

Beautiful stuff! :)
a_shorething
Posts: 289
Joined: Sep 10th, 2013, 5:26 pm
Location: New Jersey Shore

Re: draw, thrust, and components

Post by a_shorething »

Is this right?

2500 grams= 5.511557 lbs of force.

If so, that's pretty freakin' powerful! You could power a rowboat with a few of those. :)
Bubbles
Posts: 72
Joined: Aug 14th, 2013, 6:25 pm

Re: draw, thrust, and components

Post by Bubbles »

a_shorething wrote:Is this right?

2500 grams= 5.511557 lbs of force.

If so, that's pretty freakin' powerful! You could power a rowboat with a few of those. :)
Yes it is!!!!! :D :D
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