its got a 35mm prop on it at the moment, the most recommended was a 38mm but where i got my bits from did not have a 38, just 35 and 40.
No, i never did get a response from anyone regarding running the motor in both directions,
As you can see, it clearly state permissable motor direction, other models they make have L+R in the specs.
this graupner motor i have runs slightly slower in reverse polarity, the problem is although I'm pretty sure that damage is not going to be caused by the short periods that reverse is used and really should be OK for continuous running i don't know for sure.
I will do a bit of research as I've not looked into it really, just asked on here.
Hi Steve,
When a motor is marked L+R, this means it has neutral timing and will run (about) equally fast in both directions, important if you're going to run twin motors with counter rotating props.
The R from your motor means it has been timed to run faster in that direction (Germans look from the motor towards the prop when determining L or R).
As already mentioned earlier, viewed from the transom, the prop should turn counterclockwise.
A rule of thumb is that the propsize should not exceed the motor Ø (strictly speaking the Ø of the armature), so a 35 S is on the small side, the boat will not be very fast and the motor will stay cool.
The 9,6V motors are/were run in competition boats on 12-14 cells, so on 8,4V it'll be very sedate, getting the cellcount up will make the boat more lively.
When you do that, go back in propsize (the 35 will do) and make short runs (2 minutes max), come in and check the temperature of motor, ESC and cells.
If everything stays cool enough, try a bigger prop.
I've been running the Graupner 2318,xx K-series hydro props in subsurface applications aswel as the S props, both work well.
When you're carrying sufficient capacity to achieve long runtimes, keep in mind the brushed motors are only 75% efficient, the rest is transferred into heat, most of which originates at the brushes.
Adding brushtab cooling is a very good way to keep them cool.
It's very simple, just solder a piece of brass pipe onto each brushtab and link them to the cooling circuit.
Just make sure you don't create a short to the can, the silicon tubing acts as an insulator if need be.
Cover the coil with shrinkwrap, to press it tightly on the can.
Adding heatconductive paste enlarges the contact surface.
Should the coil prove to ineffective, make a full cooling jacket, like on the 700 Neodym in the picture:
When running in salt water, make an inlet for the ESC and one brushtab, and an inlet for the coil/jacket and the second brushtab.
The longer stretch of tubing will avoid losses due to the conductivity of salt water (no, this will not cause a short).
Regards, Jan.