New motors/servos for the spool and rudder

[aaron4522]

Likely going to switch the rudder odrive for a servo and keep an odrive for the sail (if mech team decides to keep the spool design).

According to this equation equation we'd need ~20-30 kg/cm of torque for our rudder.

Currently we use a Turnigy Aerodrive SK3 which has 18 kg/cm of torque according to a spreadsheet that tom did (dunno how accurate)

TODO:

• Find a new rudder servo we can buy
  • 20+ kg/cm
  • 180+ deg range
  • <0.5s for full 180
  • Ideally waterproof
  • Consult mech team on what they want to fit the shaft
• Find a new sail servo/motor we can buy
  • Consult mech team to see if they plan to do a spool, pully or some other mechanism for pulling in the sail
  • Figure out torque requirements, (our current 1.8 Nm motor works great with our spool and sail)
  • Choose between either a DC motor + encoder or a winch servo
    • With our current spool it takes ~4 motor rotations to fully bring in the sail. Sail winches can do ~3.5, but making a bigger spool means less rotations are necessary.
    • If choosing a DC motor + encoder, figure out whether we really need an odrive encoder or if we can get away with the cheap encoders embedded into the motor itself

[aaron4522]

Found by Conrad:
Rudder: https://www.servocity.com/d845wp-servo/?sku=3684500
Sail: https://www.servocity.com/stingray-4-servo-gearbox-0-68-sec-60-15-rpm-1400-oz-in-torque-450-rotation/

• Consult with mech team & Buy