Item 0423
DESIGN:
UniCopter ~ Rotor - Hub - ARR - Filament Winding
Overview:
Preliminary work on the producing of a filament-wound carbon composite rotorhub by the
CNC Workstation.
Sketch of Hub:
xx
Sketch of Filament Winder:
(Will eventually be moved to the CNC Workstations area)
Xx
- For the Y-axis the existing Parker Daedal 400 mm (15.75") linear slide table
Item 1472 should be ideal. It has a fast travel.
A longer one will probably be required for the X-axis.
Parameters:
This work is currently being based on DESIGN: UniCopter ~ Rotor - Hub - LAYOUT (4) for Lycoming
Stem diameter of blade root is 3".
Opening on bottom of rotorhub is approximately 8.5" diameter.
Opening on top of rotorhub is as small as is practical for inspection and maintenance.
- Consider winding the sleeves for the pitch bearings and the crossed-roller bearing first.
- The rest of the winding then becomes a joining of these 4 or 5 sleeves ( 3 or 4 blades) so as to withstand the forces and moments between them
- Consider the effect of the difference in thermal expansion rate between the carbon hub and the steel; ring gear, hub bearing, pitch bearings (may be elastomeric) and other metal parts.
Manufacturing Process:
Produce, by filament winding, the inner central vertical tube. The layers will consist of polar (0º), +45º, -45º and 90º windings. The mail form will be in the shape of a short cylinder with domed ends. Into the both ends ar grooves for later parting. The parting of the composite will totally remove the lower dome and a partial removal of the upper dome. The male form is extracted via the bottom. One or both removed domes may be later used as the enclosure cap for the top dome.
Produce by filament winding the 3 or 4 horizontal tubes for the blade roots. They will have an outer flange on the inner end.
Machine holes in 3 or 4 places in the central vertical tube. The machining will include a step for the outer flange on the blade root holders.
Bond the 3 or 4 horizontal tubes (blade root holders) into the vertical tube. This construction will now withstand the vertical and horizontal radial loads plus the axial load from the inner blade root bearing.
Bias wind towpreg over the above assembly. Bias wind over the horizontal tube. Wind 2 horizontal tubes CW then 1 CCW and keep repeating. Occasionally, wrap 3 horizontal tubes and then continue 2 and 1 so as to balance out the winding. Continue winding until there is no room to go further. The following picture is a crude and partially wound example of this.
This winding should provide sufficient bracing for both blade root bearings in the in-plane and out-of-plane directions.
Add any additional components.
Inject all gaps with chopped carbon and epoxy or micro ball and epoxy filler.
Add additional core spacers to give the final aerodynamic shape of the rotorhub.
Filament wind &/or lay-up the external shape of the hub.
Machine the internal tubes where necessary.
Finish the outside of the hub to give the desired aerodynamics.
- If excessive filament (by weight, price, or excessive strength) is used in the winding, consider doing an inner winding (as shown but fewer wraps) for the inner pitch bearing loads. Then overlay the winding with four specially contoured cores. Then overlay the cores with an outer winding for the outer bearing loads.
Concerns:
What provision is made for adjusting in-plane and out-of-plane blade alignment?
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Last Revised: October 4, 2005