Im going from a 6v direct drive 970 motor back to my BC gearbox with (2) 550 sized 12v motors on my bis this year and was wondering what motors guys are using that are running 12volt setups. I have never ran 12volts with this gearbox and hope to get the acceleration out of the hole that ive never been able to obtain on 6volts. I have some motors that another battler has used that are working great giving him just the RPM and low amp draw he needs and have a pair to try out but, there is no information on the motors to see the make. They appear to be cheap surplus motors to me but i figured i would try and get some help from you all. I see battlers has some 12volt motors and was thinking about ordering some from them to test and see how i liked them. Anyone else have any suggestions or experience on good 12volt motors that have the ass to not burn themselves out and have the rpm i need? thanks -Neil
I have 2 versions of the 970 motor for my Bis. One 12v Which I run on 6v and the other is a straight 6v. Sounds like your running a straight 6v with high rpm. Depending on the prop it sounds like your motor is heating up quite a bit. Course depends on the resistance the drive shaft is experiencing in th stuffing tube and the alignment from your motor shaft to the universal connector. At Nats I used my 12 v motor on 6 v using a 2 in prop 4 blade 25 pitch. I used drag discs crudely made at the site and attached to get the speed to 24 sec. The model ran the entire event this way with no issue on the motor and using the pate style rudders the model was maneurving with the Sodaks and NC's. No electronic speed controls or resistors was used. Depending on your setup 12 motors on 6v with gears using 2 inch prop should push Bis along nicely without burning it out. 6V ONLY drag discs or ESC should work nicely. There are several factors to consider including the prop size and style and the motor types. Also the gear ratio can be changed also.
I'm pushing it with a 5 blade 25 pitch prop. It did have problems with heating when i was running a 40 pitch prop, but since changing to the 25 pitch that has all went away. I just need a higher rpm motor to give me that zip out of the hole im looking for. I'm tired of being chewed up because my acceleration is so horrible.
That may be an uphill battle to match accelleration with ships powered by two props. They simply have more prop area pushing water than a single propped Bis. Going to three powered props isn't a very good solution either ... the Bis would lose it's good turning ability. Going 12v with a high rpm motor and low pitch prop sounds like a good way to go. You may also want to try a curved blade prop such as the Rabeosch (http://www.caswellplating.com/models/props.html) instead of flat bladed props.
