The inspiration for Spike came from watching children playing with Peter Lynn's Fugu (Puffer Fish). I wanted something more on a child's scale and which would, more importantly, stay inflated if the wind was not steady. Spike was the result.

Depending on his size Spike can be a ground toy with a simple one way valve to keep him inflated or a piece of line junk. To my surprise he attracted a lot of attention at Bristol 94, one reason being because the one way valve allows you to let him go and he will roll down the flying area keeping his shape. At Bristol 95 I was delighted to be greeted by another two Spikes keeping the children occupied.

Spike's construction could not be simpler, being made up of a series of hexagons and pentagons of equal length sides. This will be recognised as a geodesic sphere or, more commonly, a football. It is necessary to make three templates, one each for the hexagonal and pentagonal panels and one for the spikes themselves. The big Spike which attracted the scrutiny at Bristol is the largest it is possible to construct using 1 metre wide ripstop; anything larger than this would involve breaking the basic shapes down into triangles and enlarging.
You need to hot-cut 20 hexagons, 11 pentagons and 11 spikes. Mark each pentagon with the sewing line (shown on the drawing as a 28cm diameter circle) for the spike and hot-cut a smaller hole inside this line to allow inflation. Sew all the spikes on to the pentagons and sew eyes, if required, to two of the hexagons (I'll leave you to work those out to your own taste). I find it easiest to start at the back by sewing hexagons to all five sides of one of the pentagons (put a clothes peg or something on the spike to save confusion later). Carry on by sewing on the next five pentagons then five hexagons etc. until you have the completed sphere with only one pentagon open. The size of the opening will be dependant on the depth of your seam allowance so measure around the opening to get the length of the fabric needed for the mouthpiece ( don't forget a seam allowance to complete the tube). I make the depth of this piece the same as the side length but it is not critical. Sew to the five sides of the opening and sew the two edges together to form a tube. Finally reinforce the edge by binding with Dacron
If you wish to incorporate the valve mechanism prepare another pentagon and cut an A4 size hole in the centre and replace with a mesh panel. Cut out and hem a piece of fabric so that the finished size is about 5cm larger than the hole in both dimensions. This is tacked over the hole at each corner so that the corners of the panel are tacked to the corners of the mesh. This is very important since without the resultant bagginess the valve will not work. Sew four sides of the pentagon into the completed sphere and insert a zip into the fifth to aid deflation (this is absolutely crucial if you want to get Spike deflated without waiting ages!).
The bridle is a simple five legged affair which I attach simply by melting holes through the Dacron and tying on.
To make Spike as a piece of line junk simply scale him down although anything smaller than a 10cm side gets a bit fiddly!