I've built an operational torpedo, 17.5 inches long, 1.5 inches in diameter for my Vosper motor torpedo boat, but it's a single screw setup which causes the torpedo torque-roll and run in a circle. I'm now looking at a brushless contra-rotating motor setup giving me two prop shafts which will be set up exactly like full sized torpedoes. My question is can I run this motor (actually two motors hooked together) without using 2 ESCs? The torpedo will be spring loaded in the launch tube on deck. A magnetic reed switch will turn on the motors as the torpedo leaves the launch tube. I don't want nor need speed control. The torpedo must run at full speed until the battery is dead or it runs up on the beach. the 60 inch long MTB will be moving at 10mph when it fires the two torpedoes so I don't want to run over them before the boat can be turned away so they have to be moving fast. Any suggestions on how to run these brushless motors wide open without ESCs and not damage them?

See the boat and torpedo details at: http://web.me.com/hookpilot

Click on "Hobbies" at the top of the home page to see build and operational photos and a video of the MTB underway. I've done major work on the superstructure of the boat and replaced the center stuffing box, prop shaft, and propeller. After the torpedoes are done, depth charges will be added that roll off and possibly (if permits can be obtained) detonate underwater. That system is already designed and under construction.

Thanks,

Mike in Honolulu

Have you try this site: http://www.pt-boat.com/torpedo/torpedo.html

Also if you check his page he has the roll of depth charges i believe.

Thanks for the info. I've worked with Pat at pt-boat.com for over 5 years. He helped me out with the Browning .50 cal machine guns on my boat. My challenge is to use an outrunner brushless contra rotating setup. From what I've read, you must use a brushless ESC with each motor. I'm looking for a work around and wire them up without ESCs if possible. The Graupner Speed 300 I've installed in the first torpedo isn't enough power and it veers to the right quite a bit. The outrunner contra-rotating set up should give me the power and torque cancelling to get the fish to run straight and fast.

Thanks,

Mike

Might it not be simpler to use one motor and gears? If there are two separate shafts, 1:1 gearing will do the job. If co-axial, it needs either two layshafts to get the reversal and return to the outer shaft, or a belt and one layshaft.
I have heard that some ESCs can tolerate driving two motors. Just running flat out, there shouldn't be a problem as long as the controller can handle the amps, just reverse any two of the wires on one of the motors, and it will run in reverse with respect to the other.