Good Morning All,
I thought some of you might be interested in my experiences in getting my Shannon control system up and running. The hull is now complete and painted and the drives have been fitted, and tested.
The problems started with the servo drives to the steering nozzles and reverser. The first set of servos I tried [big digital brutes from Hobby King with no mechanical end stops] went haywire when first connected, wrapping the connecting bowden cables to the jet drives in knots. After a lot of head scratching, I concluded that the power drain on the servos was dragging the 5V supply down and causing the control system to crash.
Several rebuilds of the control panel later, I have now sorted out all the problems and everything is working fine, so here is some advice for those of you who have not got around to the electrics yet, in the hope that you will not have all of the problems I did.
I changed the servos to Tower Pro MG958 from Servo Shop - Very high torque, but controllable provided you get the power supplies right.
I changed the 5V supply to the control system from the BECs to separate 5V, 3A voltage regulators powered directly from the main batteries [Big heatsinks in photo of control panels]. The ESC BECs are now not used.
I fitted brass distribution busbars from the 5V supply [6 mm x 0.5 mm] under the control panel, with large reservoir capacitors across the 5V supply.
All servo power supply wiring [Red and brown wires] is now soldered directly to these busbars, with only the yellow control wire connected to the radio system. I strongly recommend that you do not try and power big servos from their usual servo connectors via the radio receiver. You will get trouble !
The control panel photo shows my layout. Most of the wiring is hidden underneath.
The six circuit boards in the middle are all my own design servo scalers, allowing me to calibrate all of the servo positions, rotation directions and rotation angles independently for each servo and ESC.
Also, the maximum rotation rate of the reverser servos is controlled to limit the maximum servo current [about 0.5 s for full operation, as this servo is subject to particularly heavy loads.
The other two small boards are digital control boards for any lighting I decide to fit at deck level [not yet thought about in detail].
The custom radio receiver on the left will eventually be mounted in the superstructure.
ESCs are 85A models from Hobby King.
Motors are Rotor Star 830KV brushless.
Batteries are 5000 mAh 4S LiPo, protected by big Automotive 50A fuses.
I hope this will help some of you. If anybody needs help with electrical or control problems, just ask.