A home-made stealth bomber - the ideal accessory on a summer day, writes George Buchanan
We go kite flying in the summer. The weather is nearly always perfect: blustery winds, scudding clouds, squalls of horizontal rain - the very thing for soaring birds and kite flyers.

Now and again we make a kite. Of course one can buy a kite but we prefer to make our own. The ones we make are large, slow and heavy, and resemble monstrous stealths sliding across the sky. In strong winds they are difficult to fly, prone to spectacular crashes and limb wrenching surges of power. In these conditions they might, at best, last a few days, and survive a dozen nosedives and cartwheels, before the sticks splinter, the seams tear, and the joints spring loose.

Cattle and walkers on the Common may have seen our latest monster flying high. You can't buy a Flying Manta but this is how to make one. It shouldn't take more than an hour.

Paradoxically, because the materials are so heavy, it has to be quite large to fly. Twelve and a half square foot of wing area is about the minimum viable size for summer stealths.

For the wing fabric you will need a scrap of damp-proof membrane (which you can buy from a builders' merchant), four long bamboo bean sticks, a roll of parcel tape, a roll of carpet tape (the reinforced kind), a key ring and a wire coat hanger. To cut and twist the wire you will want a pair of pliers, and unless you have teeth like a ferret, you will need a knife to cut through the tape. An unexpected ingredient is the spring from a derelict clothes peg.

Using the wire from the coathanger, fashion the twisted inserts illustrated (fig 1). Fit them in the wide end of each stick: the Z shaped one goes into the centre stick, and the two loops fit in the ends of the outer sticks. Bind some parcel tape round the ends to prevent them splitting, and secure the inserts by knotting string to them and taping the ends of the string to the bamboo.

Fit the three sticks together. The Z-shaped wire is inserted through the wire loops in the outer two sticks, and secures them. Lay the sticks in position on top of the plastic sheet and cut the sheet to size (fig 2). Tape the edges of the sheet to the two outside sticks. Use the carpet tape at the point, at the end of each stick, and at one or two intermediate stations between.

Make the anchorage wires for the cross stick (fig 3), and tape them to the side sticks, equidistant from the point. When the kite is laid flat, the cross stick should be about two inches short of a fit. In the air, the wings sweep upwards and hold the stick in position.

Now fit the harness strings. These comprise a centre loop which is fastened to the point, and runs to the very end of the centre stick, and one intermediate string, that passes through the wing and is tied to the centre stick, more or less at its centre.

Before fastening the rear end of the centre loop, thread the string through the barrel of the clothes peg spring. I have illustrated a round turn and two half hitches which is suitable for tying the ends of the string.

Knot the intermediate string to the middle of the centre stick, and pull it tight. Make a small incision in the wing, and slip the string through. With the kite upside down on the floor, pull the centre loop taut, and fasten the intermediate string to the barrel of the spring which (you will notice) slides freely along the centre loop. This gives you the adjustment facility you need to control lift.

The kite string is fastened to the barrel of the spring, and its position on the centre loop determines lift. This is found by experimentation. Too far back and the kite lurches backwards, too far forwards, and there is insufficient lift. To secure the spring, take a single hitch round one of its arms as illustrated (fig 6). Fix a shackle or a substantial key ring on the spring as a fixing point for the kite string.

The tail should be long, and have considerable windage; its drag helps keep the kite head to wind. Make the tail from offcuts of the plastic sheet, and make it longer than you think necessary. Cut the tail to length when you first fly the kite: ie if it doesn't lift, snip off a few feet.

Secure all the side seams with parcel tape. At close quarters it looks very amateurish, but at 20,000 feet it doesn't notice.

I made the winder from two 9-inch lengths of 2 x 3/4 inch pine, and two 9-inch lengths of broom handle. (fig 9). You will need tough string to hold this kite; ordinary kite thread will snap. Polypropylene baler twine or garden string is ideal.

Fly the kite in a wide open space, miles away from power cables, and thunder clouds. If Defenders and Troopers, and four wheel drive Subarus trundle across the turf to get a clearer view, wave them away. Gentle as a lamb in soft winds, in rough weather the Manta is an unpredictable and short tempered beast, prone to violent changes of altitude. It might take a sudden dislike to them, and dent their lids. And grapple tight to any child weighing less than 11 stone to make sure they don't soar skywards. In an emergency, let go the string; given its freedom, our Manta tumbles gently to earth.