FLIGHT DESIGN EXXTACY Manuel utilisateur

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Exxtacy

Repair and Tuning Manual

Construction Basics

D Cell Repair

Rib Repair

Tuning

Exxtacy Construction Basics

The Exxtacy is built with carbon fiber and Kevlar/Aramide honeycomb. The Exxtacy’s main load bearing structure is based on a D cell, aptly

named because of its cross sectional shape.

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The honeycomb layer is surrounded with carbon fiber, and the front, curved portion, of the D cell has fiberglass covering on the outside. The

fiberglass covering provides a means of visually checking for damage, as any area that has been affected will be readily identified by white streaks.

The spar is the vertical portion of the D-cell and is protected by the curved surface to the front.

The ribs attach to the D-spar, and swing out into position, to hold the rear portion of the sail. The sail itself fits completely around the front of the

D cell, and is held together, in the back, with Velcro, and strings to the end of the ribs for tension.

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Along the back of the D cell, at the top and the bottom of the spar are long layers of carbon fiber belts that run the entire length of the spar. There

are several layers of belts, near the nose, with decreasing layers toward the tips. These belts provide the main load bearing strength in tension and

compression, with the front or curved portion of the D cell providing torsion stability.

The belts are looped around steel connectors, at the top and bottom of the D cell, at the nose. This is where the two spars attach to the aluminum

keel.

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The controlbar is very much of the standard hang glider variety, except with significantly shorter downtubes. The front and rear is held by regular

wire supports to the nose and the rear of the keel. Control cables are hooked to the corners of the basebar that run through a fiber pulley out to the

actuator that raises the spoilerons.

D Cell Repair

The most common damage likely to occur to the D cell is a dent, or a puncture. The surface of the D cell is covered with a fiberglass layer that

allows for ease of visual inspection. You can sight along the length of the D-tube with the sail removed to catch any damage.

Check for any irregularities in the smooth exterior. You can also press with your thumb to feel for soft spots to determine the extent of any damage,

beyond any obvious surface blemish.

Begin a repair by drawing a line with a felt pen approximately 1/2 inch outside the perimeter of the damaged area (as determined by sight and by

pressing your thumb).

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Then, using 60 to 80 grit sandpaper, sand through the outer layer of fiberglass, and the exterior layer of carbon fiber. Sanding should be at a

45-degree angle to the outside surface of the damaged area, so as to allow even load distribution of the repaired area with the surrounding structure.

Below the sanded area you'll find the Kevlar/Aramide honeycomb. If the honeycomb is crushed, then it will need to be removed. This can be done

with a knife, making sure that the outside edge is cut away at a 45-degree angle to the outside surface.

Once you have removed the honeycomb, inspect the interior layer of carbon fiber for any damage, to determine whether it will need patching. If the

honeycomb isn't damaged, you can check the interior carbon fiber surface, by poking through the honeycomb with a pair of tweezers. If the interior

layer has been punctured, or deformed, draw another line with the felt tip pen 1/2 inch outside the previously sanded area (this previously sanded

area encloses the extent of the damage plus a 1/2 inch on each side) on the outer surface of the cell tube.

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Sand this newly marked area down to the honeycomb, and scrap away the honeycomb down to the lower level of carbon fiber, keeping the sanding

and the scrapping at a 45-degree angle to the surface. If you have to go down this far, you have now exposed the interior carbon fiber layer to an

extent of inch on all sides outside the original damage to the exterior carbon fiber layer. You can remove any of the exterior carbon fiber layer that

has been damaged.

Lay a sheet of very thin clear plastic (like from a plastic bag) over the newly sanded, damaged area, and using a felt pen, draw a circle equal to the

size of the most interior clear area on the interior carbon fiber layer.

You are going to outline the size of additional patches in a similar manner on additional pieces of thin plastic. The difference between these

patches, and the one that you will place on the interior carbon fiber, if you go down this deep, is that they will be 1/2 inch wider on each side then

the hole that they are covering.

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The patches will be marked in three ways. First they must be marked for the size of the patch, itself. Second they must indicate the orientation of

the patch, typically by an arrow pointing to the nose end of the spar. And third, they must be marked with a crosshatch to indicate the direction of

the carbon fibers that the patch will be repairing. A circle, an arrow, and a crosshatch.

After the first patch that fits onto the interior carbon fiber layer (if you find damage to the interior layer and have to go down this far), each patch is

sized approximately 1/2 inch larger than the area being patched. The third patch is 1/2 inch wider on each side than the second patch and the

fiberglass patch in another 1/2 inch wider on each side.

Cut the new pieces of carbon fiber, using sharp scissors, into squares that are roughly somewhat larger than the size of each of the patch marked on

the plastic sheets.

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Place the newly cut carbon fiber sheets over the face down clear plastic pieces (that is flip the thin sheets of plastic over), such that the direction of

the carbon fibers match the cross hatch directions indicted by the markings made earlier.

Measure out epoxy resin and 1/2 as much hardener, and mix each together thoroughly using a disposable stick.

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Using a stiff brush, carefully apply the resin to the patches laid on top of each of the clear marked plastic sheets. Stipple the resin up to the

indicated patch size on the plastic. Do not use a brushing motion, as this has the effect of pulling the carbon fiber weave apart. Also, use only

enough epoxy resin to cover the cloth, cause it to adhere to the clear plastic, and to penetrate the cloth completely.

When you are ready to apply a patch, carefully cut along the line of the patch as marked on the clear plastic using sharp scissors.

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Apply the first patch making sure to orient the arrow on the outside of the clear plastic in the correct direction (say with the arrow pointed towards

the nose), and positioning the material directly over the affected area oriented along the carbon fiber strands on the interior surface of the D-cell.