Zep Sims! The venerable Dawn of Aces II as well as the mammoth X-Plane each offer flyable zeppelin sims. DoA allows one to field the fictional LZ30, a generalized version of a World War 1 combat zep. X-P comes with a demo airship, the well-known Hindenburg. The lively modeler's scene associated with X-P has produced both Goodyear and Fuji blimps, as well as stranger stuff.