On newsreel shots of the Second World War, one can often see kite-balloons hanging over cities. They did not allow enemy planes to descend for spot bombing. Strong cables that attached kite-balloons to the ground could damage or even fully destroy a plane.

Today we can observe the regeneration of this method of defense against aircraft. The British company Allsopp Helikites Ltd. has developed a miniature hybrid of an aerostat and a kite. A three-meter long tailed cushion is attached to a cable, has a keel for stability and is filled with helium. The aerostat called Helikites can lift a 3-kilo load. In addition to scientific, advertising and other special purposes, Helikites can be used for creating air obstacles to low- flying objects, first of all to helicopters.
The thing is that in addition to the rope that attaches it to the ground, every Helikites hanging in the air has several loose strong ropes. Such ropes easily wrap around helicopter blades causing the aircraft to crash. A box with a Helikites is provided with a simplified hand-operated winch and a 13-kilo gas-bag – that is all the defense complex consists of. The aircraft is filled with helium at the launching place within a couple of minutes.
The costs of defending a territory equal to that of England against air raids are comparable to the cost of one military helicopter. 
Two principles are at work here – a miniature aerostat carries several loose dynamic ropes that can wrap around the rotor blades.