Since the 1850s, engineers have been experimenting with powered lighter-than-air flight, essentially balloons with steering and propulsion. Like other early aeronautical experiments, the trial-and-error period was lengthy and hazardous. Dirigibles (with internal support structures) and blimps (powered balloons) were filled with lifting gases like hydrogen or helium, intended for many uses, from military and research to long-distance passenger service. The growth of the airship suffered numerous setbacks, including the famous Hindenburg disaster in 1937, and never developed into a major mode of travel. Despite the challenges, more than 150 years later, a number of airships are still in use and development around the world as cargo carriers, military platforms, promotional vehicles, and more. (See also 75 Years Since the Hindenburg Disaster).