Congress sees model of new proposed American-designed dirigible. Washington, D.C. June 9. Rep. Edward A. Kenney, (right) of New Jersey, Chairman of the House Interstate Commerce Committee, viewing a model of a new american designed dirigible displayed at the Capitol today. Roland B. Respess, President of the Respess Aeronautical Engineering Corp., is pointing out the features of the ship to the House member. The House Interstate Subcommittee is hearing the witness on a bill recently introducted to authorize the loan of $12,000,000 for constructing two eight-million-cubic-foot dirigible airships, a large american airship plane, and Atlantic operating terminal with a veiw toward establishing twice-a-week American Transatlantic airship service. 6/9/37

The main types of airship are non-rigid, semi-rigid, and rigid. Non-rigid airships, often called "blimps", rely on internal pressure to maintain the shape of the airship. Semi-rigid airships maintain the envelope shape by internal pressure but have a supporting structure. Rigid airships have an outer structural framework which maintains the shape and carries all structural loads, while the lifting gas is contained in internal gas bags or cells. Rigid airships were first flown by Count Zeppelin and the vast majority of rigid airships built were manufactured by the firm he founded. As a result, all rigid airships are sometimes called zeppelins. In early dirigibles, the lifting gas used was hydrogen, due to its high lifting capacity and ready availability. Helium gas has almost the same lifting capacity and is not flammable, unlike hydrogen, but is rare and relatively expensive. Airships were most commonly used before the 1940s, but their use decreased over time as their capabilities were surpassed by those of aeroplanes.