Homebuilt ROVs Forum

Now, if I test my thruster with this type of nozzle and it is a good performer, and I share my 3d files here so that anyone else can make them... I could, at least theoretically get in trouble right?
Not that I think they would ever bother with this small size hobby stuff

No, you can't get in trouble unless you are profiting (monetarily) from someone else's patented material.
If you are giving away a file, you aren't profiting, and hence, in the clear.

I am working on this now also. I hope to get a design done and printed by the end of the month. I know Korts are about 1:2 length to inside diameter. The ratio on the Rice patent does not look like any of the actual ones as the ratio on that is closer to 1:1.


Anyway let me know what you come up with. I don't have a printer so I will have to wait for someone to do it for me. I will post once I get my design done. I am thinking about 3-6 vanes that connect the nozzle to the brushless motor backplate.

Here is what I have so far for my D2836 Turnigy motor. It is made for a 60mm prop cut down to 50mm.

I actually printed a kort nozzle today (No particular shape, just thought it looked right), it is cambered and it's more than tripling my thrust output. I'm using a 700kv out runner with a 40x57mm prop. Before my nozzle I was measure about 2.1lbs (.95kg) of thrust to 6.6lbs (3kg). (Please keep in mind I'm using a sub-par baggage scale, but it did feel about right) Of course that's only in one direction I haven't yet measured reverse. I did read on Wikipedia that a NACA 4415 airfoil works well, I'll give that a try tomorrow.

As of right now, I'm trying to figure out if there are any feasible bi-directional nozzles out there, so far no luck. The only thing I can think of is a straight tube that just keeps the stream together.

Also, if anyone wants to send me airfoil's to try out I am more than happy to print them and do some testing.

Links to my thruster parts
http://hobbyking.com/hobbyking/store/uh ... oduct=6246
http://hobbyking.com/hobbyking/store/uh ... duct=13203
http://hobbyking.com/hobbyking/store/uh ... duct=11742

Those are definately interesting numbers. What was your amperage draw like with and without the nozzle?
Keep testing and posting and I'll keep following.

scubersteve wrote:Those are definately interesting numbers. What was your amperage draw like with and without the nozzle?

Unfortunately, my multimeter only goes to 10Amps, I tested it for a second, and it read 17. But my ESC isn't leaking the magic blue smoke so it must be under 30 amperes.

Moving forwards or, in this case back, I may have misled you all. I found my better luggage scale and retook some measurements, here's what I found:

Without a nozzle:

• Forwards - 3.60lbs (1.63kg)
  Reverse - 2.03lbs (0.92kg)

With my arbitrary nozzle:

• Forwards - 6.00lbs (2.72kg)
  Reverse - 2.00lbs (0.91kg)

And finally with the new Rice nozzle I pulled:

• Forwards - 5.00lbs (2.10kg)
  Reverse - 2.6lbs (1.2kg)

For the Rice, I traced it out as best I could in CAD, referenced from the patent drawing posted by scubersteve. Tomorrow I'll try out the NACA 4415. I've heard good things from Wikipedia, and it seems to be the most referenced airfoil (Hydrofoil?) that I could find. Although I really have no idea about angle of attack, so I'm just going to go off of the illustrations I could find. If anyone has any other suggestions please let me know.

I guess this is my life now, printing and testing kort nozzles. Oh well.

Today I wasn't able to get around to the NACA 4415, but I did try out a shorter variant of the Rice nozzle. Seeing as how so many different companies, individuals, and suppliers have such short nozzles. So I've shortened the Rice from it's original 2.5 inches (6.4 cm) to about 1.2 inches (3.1 cm). So far this has proven very ineffective:

• Forwards - 4.08 lbs (1.85 kg)
  Reverse - 2.34 lbs (1.06 kg)

That being said I might do a retest of the shorter rice as I had a larger gap around the blade than I would've liked. So to be continued, I will try my hardest to get both of those tests in.