For a single prop drive ship like Suffren, I've done stuff like have a 33-35 tooth gear on the prop shaft, and built the motor mount so that the motor can slide up and down, and so that the 11-14 tooth gear on the motor shaft will mesh nicely with the driven gear. Not a formal gearbox, per se, but reduction gears in any case. I'll try to find a pic.
So maybe I won't have to go as complex as I thought I would. What gears do you think I'd need to get Suffren up to speed with the setup that you suggested? Beaver
Based on my experience and what I have seen in others' ships: For the Suffren, figure your gears for 4000-5000 RPM out of the water at the prop on a 550 motor. You'll need to know your motor's RPM spec for your planned voltage level, I've seen 550s range from 4000-18000 RPM at 6v. Your ratio will probably be somewhere in the 1.5:1 - 3:1 range. (Something you probably already know : The more you reduce, the happier your motor will run and with more torque at the prop, but if you reduce too far, you go too slow. )
I have a 7.2 volt motor, so that would give me 180000 rpms. You said that I'd need a 4-5 thousand rpm out of the water speed on my shaft. That would mean that I'd need a 4 to 1 ratio on my gears, right? Beaver
Oops, got a little carried away with my zeros. It was suppose to be 18,000. I'm going to be using a ESC. Beaver
I'd find a motor with lower kV, getting 4 to 1 reduction is tricky without making a double-reduction gearbox.
When you take the %throttle way down, you lose a lot of efficiency and some torque. I'd really get a diffrent motor, but it doesn't cost you anything to try with the one you have.
Maybe I'll try the one I have, and if I don't like the way it works I'll just get a different one next time I order from Hobby King. Beaver
So today I was experimenting with making a plug to cast turrets out of for Suffren, and I was getting along nicely when all of a sudden I cut myself on my new scroll saw. Nothing too serious, just bled a lot. All major cutting is being post-poned until this heals. I learned one thing from this whole ordeal though, not to push your wood into the saw while looking away. More update on the plug later, Beaver
Ugh. Clean it well, bandage it with some antibiotic ointment, and how long has it been since your last tetanus shot?
All of those steps have already been taken, but thanks anyway. Not to worry about the tetanus shot, it's still up to date. The cut is almost healed, so resumption of the plug for turrets will be soon. Instead of working on cutting pieces for the plug in the evenings, I've been working on drawing ribs for HMS Rodney. Not my most favorite job in the ship building process. Not to worry though about me starting another ship before I get any done. Vows have been taken not to start any more ships "except" plugs until I get Suffren running and battling. Beaver
Well, I've been disappointed for the last few weeks for not buying the right motor for Suffren, but I've decided that I'm going to try and make it work. I think that between the pitch of the props, and the lowest gear ratio possible from BC, and ESC on the motor, and the throttle on the radio, I should be able to get the speed down to 24sec. Do you guys think its possible? Beaver
Well that might have been possible a few weeks ago, but the local hobby lobby closed this year. But, I think I found a solution; these guys have the right gears to get me about where I need to be, and they're about the same price as BC. http://www.kershawdesigns.com/Pinions.htm Beaver
The 5mm bore is not what I wanted, but they sell a reducer for 1/8". I can't seem to find anything that will get me as close as these will to my speed. If nobody shows me a better choice, I'm pretty sure I'm going buy these. Beaver
