The first RW4-1.0 reaction wheels are getting ready to ship out. This is an evolution of the earlier RW3-1.0 wheel, built rad-hard and intended for long-duration GEO missions. Recent vacuum testing confirms that the power consumption of this wheel is greatly reduced compared to its predecessor:
[For those who are interested: in this revision of the motor design I paid careful attention to the fringing magnetic fields from the rotor. Where possible, aluminum radiation shielding in high field areas was removed and replaced with carbon-loaded PTFE. Where the aluminum was required for thermal reasons, it was covered with a thin layer of high permeability nickel-iron alloy. The skin depth in this alloy is very small, and prevents eddy-current formation in the aluminum substrate. That's all it took to reduce the drag losses to 1/3 of their original values!] |
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