0801

Item 0801

MAKE: UniCopter ~ Rotor - Hub - Constant Velocity Joint & Hub Spring Pitch Bearing - Elastomeric/Carbon
This page will be totally replaced

This page is the initial development work on the design & manufacturing of a specific bearing.

For general information on elastomeric bearings see: OTHER: Mechanical - Bearing - Elastomeric - General

Drawing:

Notes:
This has been moved over to other pages and eventually will be cut.
Forces

The centrifugal force, based on an over-speed of 25%, is 5,570 lbs

The design maximum flapping force, based on no coning angle, rigid blades, hover loading and an over-thrust factor of minus 25% is 2,553 lbs.

Each of the 2 bearings is subjected to the full flapping force. The centrifugal force is divided between the two bearings.

This has been moved over to another page and eventually will be cut.

Size

From information on the Rotorway's elastomeric thrust bearing;

It appears that the area of the bearing is 3.0726 sq-in. [2.115" OD & 0.75" ID]; and this is required to handle the centrifugal load.
It appears that the thickness through the shims and elastomers is approximately 1.25" thick [2 stacks of 20 shims etc.]; and this is required to handle the range of pitch rotation.

If this thrust load is split amongst 2 conical bearings then the required area, in the Y-Z plane (assuming the X-axis is the pitch axis), is (3.0726 / 2) = 1.5363 sq-in. If the design ID is 1.0000" then it has an area of 0.7857 sq-in. Since 1.5363 sq-in is the required area, the OD will be (cube root((0.7857 + 1.5363) / pi) * 2) = 1.7191"

Miscellaneous

The above information relates to using elastomeric pitch bearings in a modified version of Hub 0306.

The above elastomeric bearing set is designed to take the loading of a Rotorway blade and can probably be reduced while still retaining a high safety factor.

Idea: Have the metal grip come in contact with the metal yoke when the rotor is stationary and the coned thrust bearing are fully unload. The centrifugal force will pull the two components apart before any real motions start to take place. If metal to metal contact is not acceptable then a simple thin teflon/plastic/bronze bushing could be located between the grip and yoke.

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Last Revised: January 19, 2005