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Suitable servo for rotating T200


#1

Hello everybody,

I am currently working on developing an cataraman-shaped ASV and would like to transform the T200 thrusters (1-2 on each hull,haven’t decided yet) into azimuth ones, thus them being capable of turning left and right. Would you have any suggestion of needed torques, or recommended servos, or maybe some helpful facts that would help when doing the setup of the system?

Thank you very much.
With respect,
minu


(Adam) #2

Hi Minu,

We’ve had a few other similar projects shared on our forum, there are some helpful insights there:

Deckie
IP68

Rotating a thruster while it is running is particularly tough on both the thruster and the servo, due to the gyroscopic action of the rotating mass. Both the T100 and T200 are now toughened up in the necessary areas, and should handle this fine. A fair bit of torque is a good idea here to keep the servo from being over stressed, and a waterproof servo is nice so splashes are not a worry. The HS-5646WP should do well. Note that a decicated high current BEC is strongly recommended, as these servos can draw more current than the 500mA BasicESC BEC can provide.

-Adam


#3

Hey Adam,

Thank you for the reply. I looked into the links and explanations you provided and they do sound reasonable.

I followed this coarse algorithm, and realised that around 7.5kgcm^2 would be needed to sustain the weight of 2xT200 through bonded by an Aluminium rod(~1kg the whole assembly), whereas the aforementioned servo has already 12.9kgcm^2.

It would, as you mentioned, be worth considering the torques generated by the Coriolis and centripetal forces, maybe also the hydrodynamic ones. Or one can maybe set a safety factor to avoid going to a tedious algorithm. Are there some rules of thumbs for this?

Thank you very much.

Best regards,
minu


(Spally) #4

Guys,

Speaking form experience and by the number of broken HiTec servos I have (lets just say lots), the HS-5646WP will not cut it. I have broken my fair share of Thrusters as well and that feedback has been given to Rusty which lead to the stronger thrusters we have now.

I now run Futaba BLS172SV and never had one fail. I run 2 T200’s on steerable mounts and the torque generated when not only at full thrust but also turning a heavy boat (mine is over 25kg fully loaded) requires much stronger servos that the Hitec WP ones. I also have slowed down the servo Speed to ease the stress.

I use a Castle Creations BEC and don’t use the built in BEC off the Afro ESC as I found out early that when the thrusters were near full speed, the built in BEC couldn’t handle the current of a pair of Hitec WP units.

I have also used the Savox units (SV-1270) wich have been proven to be reliable. I know the high torque servos are more expensive but they are more reliable long term.

Jason.