Help with 1/32 scale Scratch built Gato sub

[mattc]

I look at subcommittee's website fairly often and was hoping I could to get some help with my project. I'm building a surface running, 9' 6" long Gato class sub with 3" diameter propellers. I calculated it will displace around 100 lbs. I was wanting to use a 12v system with 2 titan 775 motors but the speed control (traxxis EVX-2) is a problem. Do you have any suggestions?

The first attached picture is an early shot of it sitting on my table saw - the sails in the wrong spot

[PaulC]

Re: Help with 1/32 scale Scratch built Gato sub

Welcome aboard, Matt! Your project is off to a great start. I'm not really the guy to go to for your question but I know we have people here who are.

[jefftytoo]

Re: Help with 1/32 scale Scratch built Gato sub

With you in spirit. NOTHING beats a gorgeous Gato!

JeffP

[tsenecal]

Re: Help with 1/32 scale Scratch built Gato sub

Matt,

at 9' 6" 100+lb, that is a massive submarine.

first, the real subs only did about 20 knots surfaced, and less than 10 knots submerged, so we dont need to get this thing up on a plane.

based on the ONE google search entry that actually listed the speed of the titan 775, and the capability of the EVX2, i am not sure those are the motors or speed control you want.

at 12 volts, the titan 775 will be running about 17000 rpm no load, maybe 15000 loaded, which is about 10 times what the scale rpm probably will end up being. i am guessing the propellors on that giant sub will want to be no more than 2000rpm, probably closer to 1500. you will need a 10:1 gearbox, or better yet, either a couple Pittman 5000rpm 12 volt motors with 3:1 gearboxes, or an equal sized brushless motor with a gearbox to drop final shaft speed down to that 1500rpm.

In addition, specs on the EVX2 indicate it has the capacity to drive a single 775, or two 550 size motors. if you stay with a brushed setup, you may want to have one speed control for each motor.

of course all the speed control info is based on info gathered for an emaxx rock crawler. your mileage may vary, since a sub is not a rock crawler

the gearboxes will reduce the load on the motor, and the speed control, but how much, i can't say.

i just can't answer any better than that, haven't got the background for a sub that big. (although i will be starting on an 8' type IX sometime soon)

[mattc]

Re: Help with 1/32 scale Scratch built Gato sub

Thank you for the info!! I'll look into this.

I agree on the surface speed - I'm thinking a fast walk. In the last few days, I came across a 32P Gato model (same scale) that was being driven from 4 Pittman motors. I've requested pictures, but I have a hunch the e-mail address is dormant.

Thanks again!

[mattc]

Re: Help with 1/32 scale Scratch built Gato sub

Dear TSENECAL,
Do you have recommendations for the 12V motors and speed control? A true novice asking for help.....