Another Charlie build lifeboat, all I did was to rebuild the rudder mechanism to get a little more throw, add some figures and give it a test.
First sail highlighted a couple of sailing issues, the motors in it are a pair of Mobile Marine Models (MMM) T4A, they are rated 6,300rpm at 12v and suggest they are a low revving high torque motor, I disagree, they have little or no torque being easily stopped with one finger, and are under powered to move this along at a scale speed. The other issue even with my adjustments there is still not enough throw on the rudder to effectively turn.
As it will be difficult to make any further adjustments to the rudder mechanism without totally rethinking and going for a ‘yoke & chain’ type arrangement, I’m going to add a mixer.
As per my mixer test article I’ve found Brushed motors are far better through a mixer, and still beat brushless at low revving, so I’m looking for a torquey 12v Brushed motor running at around 8,000rpm…
Lots of research and I end up back with the T4A motors from MMM! as a whole these motors get mainly positive reviews, so I’m thinking are the ones I have worn / seen better days….., It turns out MMM are quite helpfull and have offered to have them back and test them for me.
In the mean time I’ve been looking at the propeller, it currently has a pair of 40mm 3 bladed props, I’m pretty sure the tunnels can handle 45mm, and maybe move to a 4 bladed option……
I was right, there is the space for 45mm, so replaced them both, plastic initially due to cost, but will replace with Brass when I’m happy.
The motors are back from MMM, they replaced one of them but no fault found on the other, still not happy with them so went for an equivalent unbranded one specified at 12v 8,000 rpm, much better but there working to hard so too much heat, after about a 15 minute sail they were far hotter than I was happy with, so another rethink… However I’m happy with the 45mm 4 blade props, so back to Simon at the Prop-Shop for some nice new brass ones. Also really happy with the manoeuvrability using the Action P94 mixer
Decided to rip all the mountings out and fit MFA geared motors, these are geared 2.5:1 quoting 5,890rpm at 12v but 7,900 at 15v, so plan to run them with a 4S 14.1v lipo battery. The lipo battery will save me a bit of weight as well.
Whilst I feel happier with this setup I plan to ensure there is fuses in place from the battery and to each motor, the ESC’s are 20amp, so 3 20amp fuses in the circuit.
Successful run with e new MFA Motors, but the gearboxes are noisy! really Noisy…, I’ve packed with grease but still irritatingly noisy, there not being changed again, so its on the shelf until it comes back round to its turn, shame scale speed, fantastic manoeuvrability, but cant be doing with the rattle from the gearboxes.