Recently declassified documents reveal a 1950s U.S. Air Force effort to build a flying saucer. “Six Armstrong Siddeley Viper turbo-jet s -- 1,900 lb. thrust, 22.0” overall diameter, 525 lb weight each -- are mounted radially in the wing, exhausting inwards; and used as gas generators to drive a pair of contra-rotating centrifigual impellers by means of a radial inflow turbine,” the document says. Source: National Declassification Center
Aviator's turbine metal spinning top inspired by Leonardo’s drawings and jet turbines. 1 hour air assisted spinning time.