Item 0882
DESIGN:
UniCopter ~ Rotor - Hub - ARR - Bearings - Pitch- Elastomeric
Overview:
The coefficient of friction in an elastomeric bearing may be less then that of steel rolling bearings and seals. There is no need for seals and their additional friction.
Incoming e-mail:
"You should use elastomeric bearings for the rotor head. I have worked on helicopter in the military for about 15 years, and they seem to be the best choice. One because there is very little maintenance to them, excepted for periodic inspection, and because of the safety issued of the standard roller bearing, which is because: they do not rotate completely around so they create excessive friction due to lack of lubrication, which results in eventual failure, Sikorsky has lost several helicopter because of ball bearing. They know use elastomeric on the H60 series helicopter."
Drawing:
Axial and Radial Forces on Pitch Bearings:
From:
DESIGN: UniCopter ~ Rotor - Disk - Blade ForcesUltimate axial load on a blade = 68,226 lb.
Ultimate radial moment on a blade = 49,500 lb-in.
I would have thought that the radial loading would be greater than the axial. In other words, the centrifugal force will be the lesser of the two. The heavy weight of the blade (15.4 pounds) makes this not the case. The bearing furthest from the mast will be subjected to the (slightly) higher radial load.
For general information on elastomeric bearings see:
DESIGN: SynchroLite ~ Rotor - Hub - Pitch Bearing - ElastomericFor additional related information see:
DESIGN: SynchroLite ~ Rotor - Hub - Pitch BearingsSee:
DESIGN: UniCopter ~ Rotor - Hub - Pitch Bearing - Roller & Ball
Can the cylindrical portion of the yoke that encloses the root of the blade be given a slightly larger diameter at near the mast, so that the diameter of the angular bearing can be increased and therefor so can the diameter of the root of the blade?
Same Page ~ Different Craft:
~ SynchroLite ~ Dragonfly
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Last Revised: May 28, 2004