Aerodynamicists believed that by ionising the air upstream of an aircraft, they were changing the medium through which the vehicle was flying. Plasmas can behave very differently to ordinary gases. The electrons and ions they contain act independently, creating regions of positive and negative charge that flow through the plasma as waves. This sets up large electric fields that interact in complex ways. Engineers have some experience using electric and magnetic fields to influence the way a plasma flows, but this takes huge amounts of energy and heavy magnets that are too big for an aircraft to carry.
Plasma dynamics is much richer than ordinary gas dynamics.
In 1996, Terry Cain, an engineer working at DERA's Farnborough research lab, travelled to Russia to meet Klimov and his colleagues and repeat their experiments at the Central Aerohydrodynamics Institute near Moscow. He decided to test streamlined bodies the size and shape of ice cream cones, and Klimov and his colleagues fitted them with on-board plasma generators. Placed in a supersonic wind tunnel, these generators could create plasmas upstream of the cone. It was spectacular. Crucially, these test bodies were far more aerodynamic than the spheres that Klimov had started with.