B385

DESIGN: Dragonfly ~ Rotor - Hub

Flap and Drag Bearings:

The axis of these two hinges are coincident; and that is an advantage. [Source ~ MDD p.22]

Flapping Hinge Offset:

The rotors have an offset e of = 0.14. For other offset values see; OTHER: Flight Dynamics - Rotor Hub - Flap Hinge Offset

Blade Attachment:

Since the lead/lag is being handled at the yoke, the attachment between the blade and the blade grip must be positive. In addition, it will probably have to have an adjustment for setting the static (pre-) lead/lag.

Yoke:

Consider including the provision for a central tie-rod position, just in case the twin tie-rods do not work with the lead-lag..

Pre-Lead-lag:

The location of the pin between the grip and blade must be established. If there is the intend to have this a rigid connection then the means of locking and the angle of pre-lead-lag must be established. See DESIGN: SynchroLite ~ Rotor - Disk - Blade Lag Angle and DESIGN: Rotor - Hub - Robinson R-22

Weight and LLF:

The rotor governor should allow the hub to be lighter. See DESIGN: SynchroLite ~ Control - Flight ~ Weight Restriction.

Elastomeric Bearings (for future):

Consider the use of elastomeric bearings for;

Pitch bearings

Flap bearings

Lead-lag bearing

Tie-rod end bearings

Tie-rod central bearing

This will eliminate the concern about lubrication of the yoke's bearings (and will weight less).

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Elastomeric Bearing Information:

DESIGN: SynchroLite ~ Rotor - Hub - Bearing - Pitch - Elastomeric

DESIGN: UniCopter ~ Rotor - Hub - Bearing - Pitch - Elastomeric

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Initially for testing the concept, these bearings might be Oilite: Or look into Waitman making the bearings

Note:

The top of the rotor head should be smooth and slightly rounded. The top of it should also align with a smooth and slightly rounded blade grip. This way, if the blade on the other rotor should come in contact with this rotor's hub there will be less chance of doing damage to the blade.

Same Page ~ Different Craft: ~ SynchroLite ~ UniCopter

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Last Revised: January 12, 2004