1103

Item 1103

MAKE: UniCopter ~ Rotor - Blade - NACA 00xx - Spar - Winding

Overview:

XXX

Drawing:
Maybe

CNC Requirements:

Minimum: No CNC requires. Just have X travel with limit switch stop at each end of X-axis traveland button carriage return. Could use chain and sprockets, rack & gear or ball screw with large. The carriage stops short of the end and the tow is hand looped over the pin or quill. A-rotoation could be done manually with both ends interconnected.

CNC Axii: X, Y, Z and A. Full CNC might require B &/or C wrist motion. 5 &/or 6-axis.

Generating of G-code using Access ~ CNC Workstation

FORM: Tow:

The tow is selected, if default one is not to be used.

FORM: Spar - Tube

Used to generate the actual G-code for the Spar Liner (if employed ~ see below) and output it to a file.

A separate form may be used to generate the specifications for the layers in the tube; same as that for torque tube. The current mandrel may serve for this tube.

FORM: Spar - Layer form may be used to generate the specifications for the layers in the spar; same as that for torque tube.
FORM: Spar:

Used to generate the actual G-code and output it to a file.

Split Spar:

Consider producing the spar in two halves. There might be a vertical split, thereby creating a leading and a trailing half. Alternatively, there might be a horizontal split, creating an upper and a lower half. The horizontal split will result in more surface area at the tip for bonding the two halves. Producing the spar in two halves should allow for greater pressure on the unidirectional tow during the cure, somewhat closer to pultruded.

Another thought would be to create the spare halves as one part with an extremely small angle V between the upper and the lower halves at the tip end. This will allow for high compression during curing.

When the spare is finished, it might be bound in one hoop layer of fiberglass tow. The tip should definetly be helical or hoop bound in carbon tow.

Spar Liner:

As an alternative to the Split Spar above, consider a thin wall spar liner. It's ID.s will be the same as those which are desired for the spar. It will be hoop wound in fiberglass. It could be pressurized when curing the spar, which is inside a female mold.

The use of glass will allow for a slight expansion during pressurized spar curing. The use of glass will give less resistance to the active twisting of the spar during flight. The fact that it is inside the spar will result in less resistance to active twist. In addition, The bonding of the axial carbon tow to its surface will help hold the spar together radially. Since it is located on the inside of the spar, it will not take away from the overall width, and thereby strength, of the 'pultruded' spar, but it will be less effective than an outer wind.

Applying the Spar: Transferred from 1342

Insert a braided S-glass tube over the elastomer, Use a tube that is well oversize so that the thread angles will be far from +/-45º and close to the pitch axis, so as to minimize the resistance to twisting.

Build the pultruded spar up over the braided tube.

The following will be revised.
Sequence of Production:

Fit a braided carbon sleeve over the elastomer covered torque tube.

Add a radial elastomeric bearing at the root end to take the force from the pitch arm.

Fit one or more additional sleeves if required.

Shrink wrap and cure. If spar should bow then 1/ leave since finished blade will be mounted to the hub upside down (i.e. anhedral) or 2/ hang spar vertically.

Fit foam (or honeycomb) core over root end of developing spar. Core may have to be 2-part to place over developing spar.

Apply pultruded prepreg carbon thread. The HOW to be added. Note that the root plate is to be the small one where the carbon threads build outward.

The following is the former idea.

Sequence of Production:

Produce upper and lower webs.

All carbon threads run from root pins to temporary tip pins.

Machine leading and trailing edge of spar webs.
Machine inside of spar webs.

To match honeycomb core
C/w central groove at root end, for wires etc.

Machine off crop at end of tip.
Wrap upper web / honeycomb core / lower web sandwich with diagonal and/or chordwise filament winding of carbon

Notes:

When polar winding the spar consider cutting and restarting the tow at each change of bolt. This will eliminate the angular tow between bolts, which might break during later twisting.

Consider the possibility of winding all layers for one bolt before starting the next bolt.

The A-axis will probably have to alternatively rotate CW - CCW, since if it always rotates in the same direction it will build a twist in the tow.

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Last Revised: November 21, 2006

The above utility invention is openly and publicly disclosed on the Internet to negate an entity from patenting it, to the exclusion of all others whom may wish to use it. ~ Reference patent law 35 U.S.C. 102 A person shall be entitled to a patent unless - (a) the invention was known ... by others in this country, ..., before the invention thereof by the applicant for patent.