Description PLUMBBOB/STOKES/dirigible Nevada test Site, August 7, 1957. The tail, or After section of a U.S. Navy Goodyear ZSG-3 Blimp is shown with the Stokes cloud in background. The dirigible was in temporary free flight in excess of five miles from ground zero when collapsed by the shock wave from the blast. The airship was unmanned and was used in military effects experiments on blast and heat. On ground to the left are remains of the forward section.