1342

Item 1342

MAKE: UniCopter ~ Rotor - Blade - NACA 00xx - Torque Tube - Winding

Overview:

This torque tube is for a blade with independent root & tip control, and where the spar is affixed to the skin. The spar and skin twist together and their centrifugal forces are carried by the root pitch bearings.

This MAKE page relates to the actual construction (winding) of the torque tube.

Drawing:

The G-code file is created from FORM: Torque Tube in the database, not from a DXF file of the drawing.

The tip will have quills.

The root end diameter will probably be significantly smaller.

Bill of Material 1342

BoM not yet created

	Carbon Tubes / Roll Wrapped .170" ID x .025" Wall Thickness x 30" $8.50 ~ Aerospace Composite Products - TUR-01
	Carbon tow (probably best to use prepreg) (towpreg)
	Epoxy

The cure (or partial cure) of the inner layers must be completed and ground down, at least at the tip end, before this tip holder is cut off and advanced toward the tip. THIS INVOLVES MORE STEPS AND DELAYS THE PROCESS. - NOT TO GOOD.

Can crazy glue or laser or heating donut be used?

CNC Requirements:

Minimum: A-axis rotation, X-axis traverse with relationship to A. Perhaps a stepper motor arraignment might do this.

Maximum: Probably requires A, X, Y & Z-axis.

Picture:

See picture of winding profile on; DESIGN: UniCopter ~ Rotor - Blade - NACA 00xx - Torque Tube

Generating of G-code using Access ~ CNC WorkStation

FORM: Tow:

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

FORM: Torque Tube - Mandrel:

The dimensions of the mandrel is changed, if default one is not to be used.

FORM: Torque Tube - Layer:

Used to develop the specifications for each layer and then save them in the table [Torque Tube - Layer].

FORM: Torque Tube:

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

Database FORM: Torque Tube:

The coding for winding items such as the Torque Tube in DATABASE CNC Winding Generator are based on the drawing located on web page OTHER: Composite - CNC Work Station - Generator (winding to g-code)

The following may be moved over to the just mentioned web page to be with the sketch.
FORM: Torque Tube - Layer;

The primary inputs are;

Desired bias of the quills at tip end of torque tube.
Desired length ( on X-axis) of the layer.

The outputs are:

Actual bias of the quills at tip end of torque tube.
Actual Bias at the root end of the torque tube.
Number of tows in each tape.
Width of tape.
Number of Wraps
Actual span of the layer; from root to base of quill.
Total tow length for layer.

Description of operation: The desired bias and length are entered. The program generates and outputs the results. Results such as number of tows and number of wraps are fractional values. Whole numbers are entered for these values and then changed until the optimum results are achieved.

Manufacturing of Torque Tube:
This section will now be changed due to the winding of inner layer and outer layer groupings.

May only require motion on two axes; X-axis and A-axis.

There is very little torque required on A-axis because tow tension is only 1-2 pounds.

If a Towpreg with a low percentage of epoxy is used then must the tension be slightly higher.

Back the torque tube with rollers to handle the tow tension from the feeder?

The A-axis at the tip end will only have to deliver a very little torque to the mandrel since the pull on the tow is only 1-2 lbs and the radius arm is around 1/8th".

It may not matter if the mandrel 'bows' slightly during the 1 to 2 lbs of tension during winding since the torque tube is not required, nor desired, to be radial rigid.

Set up:

Slide short 1/8" ID composite tubing over 1/8" cable at tip end.

Place clamp on free end of cable, attach clamp to jig and draw cable very taunt. HOW

Torque tube will be built up over mandrel. 1349.html

The winding starts at the root end. And the layer change takes place at the root end.

Leave 5" of thread for quill.

The quills are to be vertical to accept the insertion of the leading and trailing spar halves.

Wrap one strand of thread up the full length of the mandrel.

Repeat with additional strands until 1/2 the band (i.e. 1 tape) has been filled.

As in 4, wrap the second band to the other quill holder.

Cover with epoxy and remove excess; if not wet lay-up or prepreg (towpreg).

Start a new layer in the opposite direction approximately 1' closer to the root and repeat 1 to 6.

Continue until a thickness of 0.1875" has been achieved. How many layers is this?

Hang vertically or brace if there is any sag, then vacuum bag and cure.

Weigh and adjust to suit required weight.

Access Note: Round down the calculated number of tows per layer because wrapping will flatten out tow slightly.

Notes:

Consider having the very first layer (or two) a 90º hoop wrap. It will provide some additional torsional strength and also be the foundation upon which the other layers are laid.

The layers are split in two with the first half of the tows going to one quill wrap holder and the second half going to the other quill wrap holder.

The layers are alternated with a 45º leftward direction then a 45º rightward direction. Reverse for other rotor so that the LH and the RH torque tubes have the same change of twist.

Winding:

Notes;

Assume that the band consists of 10 tows (tow # 1 to # 10). Each tape will therefore consist of 5 tows (tow # 1 to # 5 and tow # 6 to # 10). This will result in the first 5 tows making up one quill and the second 5 tows making up another quill, which is 180º around the A-axis from the first quill.
The very first wrap will be that of tow # 1. It will wrap with a gap that leaves room for tows # 2, 3, 4 and 5. Tow # 6 will be wrapped adjacent to # 5, but as with # 1, it will leave a gap for tows # 7, 8, 9 and 10.
Note that the bias of all ten tows will change by the same amount as they advance up the mandrel.

Related Pages ~ This Site:

	DESIGN: UniCopter ~ Rotor - Blade - NACA 00xx - Torque Tube
	MAKE: UniCopter ~ Special Tool - Rotor - Blade - Torque Tube - Mandrel
	OTHER: Composite - CNC Work Station - Generator (winding to g-code)
	OTHER: Composite - Special Tool - Thread Winder

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Last Revised: November 21, 2006

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