Hello Again.

Hello Captains

First off i like to say, i like the look of the new site. I know it been a few months since it change, but i've been really busy with school. hope everyone enjoying the great weather.

Unfortunately it look like i will not be building this summer, dealing with school and renovation. I do hope to get Libby in reliable working condition, last year ended with her hull get wet. Good new no leaks, bad new steering keeps getting stuck and drive shaft keeps slipping loose.

I also would like Libby to be a transport ship by the end of the year instead of an aircraft carrier.

 

This is how its set up I forget the name for this set up. the problem is that the screws keep slipping on the shafts. I made a flat area with a file before assembling.

 

Ill have to try it with crazy glue and hope it works.

 

Problem is with the angle your dogbone is at. The greater the angle, them more vibration as the dogbone rotates past the collar notches where the pins insert. This vibration shakes the setscrews loose.

Recommendations: if possible, remount motor so it's better aligned with prop shaft. If that's not possible, you could try moving the motor further back & using a longer dogbone (longer = less angle = less vibration)

 

I'm kind of shocked it's not throwing dogbones with that angle, this has got to be close or maybe even beyond the maximum they can even function with. If the shaft of the dogbone touches the coupler anywhere, you are beyond the true mechanical limits of what will even work. irnuke gave the best two solutions to your issue. Even if you can keep the setscrews tight in the current configuration, it seems like the dogbone itself will likely fail at a very inopportune time in battle.

 

Thanks for mentioning the angle problem, i really never thought of that. So i took mount out and sanding down the bottom and adjusted the screw holes to allow better adjusting.

Here is the adjusted mounting, unfortunately I lost the screw for the coupling.

 

That looks much better! Glad it was a relatively easy fix, hopefully the screws will stay tight now. Either way your dogbones will be much happier!!

 

Have you had a chance to look at the rudder setup yet?? If you get stumped post a picture or two and someone will have some good advice on it.

 

I got a chance to take Libby out for a little swim. The rudder assemble works, I'm guessing i worked on it last year. She ran well for 20 mins before the stuffing tube seized, i'll have to look into it later, since I have midterm and paper due the next week. I also realized how much weight needs to be added.

 

Did you lubricate your stuffing tube??

 

Hope this answers your question

 

Are those 2100KV motors? On direct drive? What voltage are you running?

 

From his built thread it looks like he's using a 3 cell LiPo battery. (11.1 v) That's WAY too many rpm's. That transport will look like a speed boat. You want a much slower motor, probably around 750kv for that voltage.
Here are some options:
Turnigy D2836/11 750KV Brushless Outrunner Motor
NTM Prop Drive Series 28-30A 750kv / 140w

 

That is what I was thinking. Those will be some good pump motors some day, it is like the one I have on mine that has lasted 3 Nats so far, but a little smaller I think. Maybe the high rpm is contributing to the seized shaft and the set screws vibrating loose. I wonder if the ESC can handle running on a single cell? For a frame of reference convoy ships are about half walking speed.

I remember building in college, hydroplaning across the pond in my first ship, the Prinz Eugen, powered by 3 380 motors.

 

Yes believe there is too much motor for the ship, I never went full throttle it sounded to scary. As far as changing the motor out, i dont see it happening in the near future.

 

You should be able to dial it back with the endstops on the radio, if yours has that option. Then swap it out for a more suitable one when you can.

 

LOL the end point will be set on 1%... and then you will still need 2in diameter drag props...