Cast on 8 sts and purl the first row.

Row 2: K 1, inc in next st by knitting into st below and then k the st itself, k 1, inc as above, k 1, continue across row ending with k 1.

Row 3: P this row and all alternate rows.

Row 4: K 2, inc, k 2, inc, k 2, continue across row ending with k 1.

Row 6: K 3, inc, k 3, inc, continue across row ending with k 1.

Continue increasing in this manner with one more k st between incs in every k row until there are 113 sts on needle. There will be seven sections in the top of the helmet.

Work cable pattern as follows:

Row 1: P 3, * k 4, p 2; repeat from * ending with k 2.

Row 2: K 3, * p 4, k 2; repeat from * ending with p 2.

Row 3: Repeat Row 1.

Row 4: Repeat Row 2.

Row 5: P 3, * sl next 2 sts on an extra double pointed needle and place in back of work, k 2, k 2 sts from spare needle, p 2; repeat from * ending with k 2.

Row 6: Repeat row 2.

These six rows constitute the cable pattern. Repeat these rows until cable pattern measures 2 inches from incs.

The remainder of the helmet is worked in ribbing of k 1, p 1. K 36 sts in ribbing. Bind off next 41 sts. K remain 36 sts in ribbing.

Join 2 sections of work at center back and k across entire 72 sts in ribbing for about 1 1/2 inches.

K 10 sts in ribbing. Bind off 52 sts. K remaining 10 sts in ribbing. Continue on these 10 sts for 3 inches or desired length of chin strap.

On next row, make buttonhole by (k1, p1) twice. Work one more row of ribbing. Bind off.

Work one inch in ribbing on the other 10 sts; bind off.

Sew up centre back of single crochet together. Sew button on short tab.