Going brushless...

I had an interesting phone call yesterday from an AMS member in Penzance.

He is very keen to try a brushless motor in a dynamic diver he is building.

I thought that brushless motors could have a lot going for them, particularly in dynamic divers(small, size, high efficiency motors etc.)

He had looked at the thread on here and pointed out that "it was rather inconclusive."

I can only agree!

Does any one have any experiences to share with brushless motors in subs?

(I note from my trip to the Dortmund show that German modellers are using brushless motors often.)

David

Last year, I met a man named Tim Senecal. He has been using brushless in his Skipjack. Here is his thread about what he used:
http://www.rcgroups.com/forums/showthread.php?t=1909533
Hope this helps.

david f wrote:
...Does any one have any experiences to share with brushless motors in subs?

(I note from my trip to the Dortmund show that German modellers are using brushless motors often.)

David

My experience with electronically commutated ("brushless") DC motors in model submarines goes back to 1994 when my rebuilt class 206A model S195 (U16) was "recommissioned" after extensive rebuilding measures (including a new propulsion train). The model has been "in service" since then for 20 years till this day and was in operation for more than 400 hours and has covered a distance of more than 200miles during this time. There wasn't any maintenance work necessary neither for the motor itself nor the whole propulsion train. So my experiences with this motor are positive without exception.
So are my experiences with the motor of my second model, a class 212A submarine S182 (U32) that is in operation since 2002.

However I must confess that these motors are of own development and construction (including the control electronics), they are designed as "wet running" motors with the rotor directly running in water so there is no need for sliding shaft seals (that may wear down by time and will cause leakage). The motors have disk rotors and are equipped with position pick up sensors so they have a clear start behaviour (even when stalled) and can run with extreme low speed. The electronic is integrated within the motor casing.

I know that some other modellers use commercial available brushless motors, mainly for fast mini submarines (that really jump out of the water), but also for larger models brushless motors have been used. The German model company Robbe has had a model kit of a class 212A submarine in the programme to be powered by a large (but sensorless) brushless motor, installed conventionally within the pressure hull (and with sliding seals for the propeller shaft). The models built I have seen worked well obviously.



Kind regards
Hermann

Thanks both for some very useful information.

Hermann has cleverly avoided he need for shaft seals but my worry about brushless motors in subs is that they tend to be high revving and I wonder how shaft seals cope with this?

There is some guidance on this in Salmon's account of Tim's experience. He has motors giving 1800rpm/volt and there is no mention of gearboxes. The shaft seal is a Thundertiger one which I see uses a Simrit type oil seal. I also see that Tim uses a programmer to limit the revs to 6000. Interesting and it obviously works.

David

Just a link to some useful information from Andreas.

https://www.theassociationofmodelsubmariners.com/t1420p15-new-project-uss-nautilus#8785