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Description
Component
Compliance
Fail SafeSystem 
Sufficient Momentum to maintain ωz <<< ωySystem 


Design

Let us assume Hermes is a thin tube with a diameter of .155m and a dry mass of 44kg. Mass moment of inertia is 
Mathinline
bodyI = mr^2
 which means that Hermes has a mass moment of inertia about the long axis of  
Mathinline
body.264275 kgm^2
. Using a 1.5 FoS on the Hermes 2 roll rate the maximum angular momentum capacity of the reaction wheel is 
Mathinline
bodyL_{max} = 2.8 hz * 1.5 *.265kgm^2 = 1.113 kgm^2/s
. In other words this reaction wheel will be designed to mitigate 1.5x the maximum roll rate of Hermes 2 at burnout.
A straightforward reaction wheel design would have maximum OD of 5.5 in or .14m. The 335kv motors can obtain a max RPM of 4800. Conservatively using 3500 RPM or 583.3 hz, we can calculate the necessary moment of inertia of the reaction wheel to be
Mathinline
body.00191 kgm^2
 which is a disk of 0.8kg or a thin walled tube of 0.4kg.PID Control References

Hardware

Pyxida will send I2C commands to a Teensy 3.5 which will PWM Control 60A Hobbyking ESC units that drive Quantum MT motors. The system is powered by a 4s LiPo battery.

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