Building a Delta

The delta we will be building follows the propotions shown in the figure below. This formula is attributed to Tony Cyphert, a San Diego kitemaker. (From Margaret Gregor's book, Kites for Everyone.)
The size of the kite that we will be making was chosen so that the side spars are the length of the available rods. The dimensions are shown in the figure below.

To make the sail a little more interesting we will divide the leading edge into three pieces, and sew three triangles of different colours together to make each half of the sail. The keel will be the same colour as the two center triangles.

Cardboard patterns have been made of the finished size of each triangle and the keel. Be careful when you are laying out the patterns. You need to leave 1.5 cm for seam allowance on most edges, and 3 cm for spar pockets on the leading edge and the center edges. The other pieces you need are

1. A quarter circle of reinforcing material to reinforce the point of the keel where the line will be attached. The radius of this circle should be approximately 7 cm.
2. Two triangles of heavy dacron to form the pockets for the cross spars. The triangles should be isosoles triangles (two sides with the same length) with a base of 12 cm and a height of 6 cm.

Step 1: Sewing the Sail

The first step is to construct the two halves of the sail. Use pencil to draw the sewing lines from the pattern onto the fabrice. Remember to add the right amount of seam allowance to the patterns before you cut out the pieces.

To sew two pieces together, place the two panels right sides together, line up the end points and sew along the finished line. To finish the seam, open the pieces out and roll both raw edges of the seam to one side.

Step 2: First center seam

Place the two triangles wrong sides together, and sew a 1 cm seam down the center line. Open up the pieces and press the seam open with your fingers. There will be the raw edges of a seam on the good side of the kite, but don't worry, these edges will disappear into the center spar pocket.

Step 3: Fold and hem the top triangle

Fold the top of the kite towards the wrong side, just below the finished points that you drew on the kite using the pattern. Trim some of the triangle off, fold the raw edge under and sew down.

Step 4: Sew the leading edge

This step requires some care. You need to tape down the two triangle spar pockets in the right place so that when the side is hemmed, the pockets will be sewn into the hem. Fold the edge (which should have 3 cm seam seam allowance along the sewing line and crimp with fingers. Fold the raw edge under and tape down to hold it while you get ready to sew.

Fold the two spar pocket triangles in half, and locate their position using the marks on the pattern, or by measuring. Take care to make sure both pockets are the same distance from the top and bottom of the leading edge.

Step 5: Hem bottom edge

Fold bottom edge along the finished line towards the wrong side and tuck the raw edge under to hem. You will need to trim and tuck in the corners to keep them sharp.

Step 6: Hem keel

Sew down the reinforcing patch on the 90 degree corner of the triangle. The straight edges of the patch should line up with the finished lines. Using the same technique as in step 5, hem two sides of the keel.

Step 7: Sew center line

Finishing up