Photo: Achim Mende.

It has been more than 70 years since the giant Hindenburg zeppelin exploded, killing 36 crew members and passengers, abruptly ending an earlier age of airships. But because of new materials and sophisticated means of propulsion, entrepreneurs are [taking another look](http://www.nytimes.com/2008/07/05/business/worldbusiness/05dirigible.html?_r=1&oref=slogin) at the behemoths of the air.