My Jet Jam Brushless Project

[FLMIBrewer]

Not a bad start for initial setup. Its definitely to hot a setup on 3s for long wot runs but for the rapid running I do, it's pretty good. The current speed where I run keeps me mid throttle mostly. Current motor is a 2212 stator, 9 pole, 6 slot i believe. Self righting is MUCH better now too. I'm thinking a a little taller stator and little less kv maybe the sweet spot to deal with heat better since I don't have a water cooling mount. Motor is the only thing that needs water cooling IMO, Esc is hardly warm. i will be tidying up the wires to lose some weight and clean up the inside.

Proboat Jet Jam
2212 4500kv upgrade
9g digtal mg servo upgrade
CC multirotor 35a esc upgrade
Mike's subworks esc/tx adapter
Dx5 rugged
Sr215 rx

[Dr. Jet]

I've had a lot of success with the little outrunners like you used in your JJ. I agree with you though, 4500rpm/V sounds a bit high for 3S, but I really don't know what kind of load the jet pump puts on the motor. If you are concerned about cooling, look specifically for a motor that has a cooling fan built into the can. It works surprisingly well, even in the cramped confined if a mini hull. Something like this may be the ticket: https://www.ebay.com/itm/Turborix-RC...wAAOSwxL1dVjnC This motor appears to have a bolt-on fan that attaches to the endbell.

In my little 15" MHZ Shovelnose, I run a 3000rpm/V outrunner motor on 2S with a 29mm prop and I can easily blow it off the water if I'm going upwind in some chop. I run my minis mostly on 2S for a lot of reasons, but primarily because I'm cheap. Depending on the hull, I'll use props from 26mm through 32mm, although things heat up a bit more with the bigger props.

When I was last at the pond, one of the guys showed up with a stock JJ. I wasn't that impressed, but it looked like it had potential with some upgrades like you have done.

Keep us posted......


UPDATE: I watched some YouTube videos of brushless JJs running. One common problem they seemed to have at this higher power level is cavitation in the impeller assembly. I would take an X-Acto knife or some needle files and remove any burrs or sharp edges in the inlet opening that would interrupt the laminar flow of water getting into the pump. You could even go so far as to make the "screen" bits of the hull into an airfoil (hydrofoil?) shape to reduce the turbulent flow going into to the impeller.

Free speed!

[FLMIBrewer]

I've had a lot of success with the little outrunners like you used in your JJ. I agree with you though, 4500rpm/V sounds a bit high for 3S, but I really don't know what kind of load the jet pump puts on the motor. If you are concerned about cooling, look specifically for a motor that has a cooling fan built into the can. It works surprisingly well, even in the cramped confined if a mini hull. Something like this may be the ticket: https://www.ebay.com/itm/Turborix-RC...wAAOSwxL1dVjnC This motor appears to have a bolt-on fan that attaches to the endbell.

In my little 15" MHZ Shovelnose, I run a 3000rpm/V outrunner motor on 2S with a 29mm prop and I can easily blow it off the water if I'm going upwind in some chop. I run my minis mostly on 2S for a lot of reasons, but primarily because I'm cheap. Depending on the hull, I'll use props from 26mm through 32mm, although things heat up a bit more with the bigger props.

When I was last at the pond, one of the guys showed up with a stock JJ. I wasn't that impressed, but it looked like it had potential with some upgrades like you have done.

Keep us posted......

I'm going to try 2s then, have not tried yet. Thanks for your advice.

[FLMIBrewer]

Is it possible and is there a correct way to install a fitting on the pump to help prime it faster and provide water cooling?

[Dr. Jet]

Take a look at this video around 4:20. His approach was somewhat crude, but I'm sure there's a neater solution using the same concept.

https://www.youtube.com/watch?v=y2UnK3USQ68