In the mid-1990s, the modern wingsuit was developed by Patrick de Gayardon of France, adapted from the model used by John Carta. In 1997, the Bulgarian Sammy Popov designed and built a wingsuit which had a larger wing between the legs and longer wings on the arms. His prototype was developed at Boulder City, Nevada. Testing was conducted in a vertical wind tunnel in Las Vegas at Flyaway Las Vegas. Popov's wingsuit first flew in October 1998 over Jean, Nevada, but it never went into commercial production. Popov's design was a great improvement in creating lift; it was able to slow the vertical speed to 30 km/h while gliding horizontally at speeds over 300 km/h. In 1998, Chuck "Da Kine" Raggs built a version which incorporated hard ribs inside the wing airfoils. Although these more rigid wings were better able to keep their shape in flight, this made the wingsuit heavier and more difficult to fly. Raggs' design also never went into commercial production. Flying together for the first time, Popov and Raggs showcased their designs side-by-side at the World Free-fall Convention at Quincy, Illinois,.