Scott Williams, age 11, of Orlando, Fla., for his question:
WHEN WAS TAE FIRST AIRSHIP BUILT?
An airship is a lighter than air aircraft that has its own motive power and can be steered in any direction by its crew. A French engineer named Henri Giffard was the first man to successfully combine an engine of sufficient power with a balloon that could be steered. Giffard's cigar shaped balloon flew 17 miles from Paris to the city's outskirts on Sept. 24, 1852.
Giffard's airship was powered by a three horsepower steam engine linked to a propeller. The aircraft moved along at about five miles per hour.
By using a rudder, Giffard could turn from a straight course. But his engine lacked the power to turn the balloon completely around and return to the starting point.
The first truly successful airship was the LaFrance, built by Charles Renard and A.C. Krebs of France in 1884. The gas bag was longer and more streamlined than those of earlier airships. The LaFrance made a five mile round trip near Paris on Aug. 9, 1884.
Many men continued to work on airships through the 1890s and early 1900s. Alberta Santos Dumont, a wealthy Brazilian who lived in France, flew 14 airships between 1897 and 1904. In 1901, he flew an airship around the Eiffel Tower in Paris, but crashed into a tree on landing. With his next airship, he completed a seven mile round trip from St. Cloud, a Paris suburb, around the Eiffel Tower and back
The first rigid airship was built by the Austrian engineer David Schwarz in Berlin. It crashed during its only flight on Nov. 3, 1897. In 1902, Paul and Pierre Lebaudy, two French sugar refiners, built the semirigid airship L&Jaune. It was successful and several more similar to it were constructed.
The work of Schwarz influenced Court Ferdinand von Zeppelin, a retired German army officer, to begin work on airships. Zeppelin was an excellent engineer and he did such outstanding work on airships that they are often called by his name.
Lift and .thrust are the two forces that make an airship fly today.
Lift is the force that raises the airship above the ground. An airship's lift comes from a lighter than air gas that raises the airship in the same way a balloon is lifted. The lifting gas is contained in a large, enclosed space provided by the hull or body of an airship.
In many airships, the hull consists of several balionets or separate compartments for the gas. Frequently, the size of an airship is measured by the cubic feet or cubic meters of hull space provided for the lifting gas.
Hydrogen, the lightest gas available, was used for lifting most of the early airships. But it has been replaced by helium, which has several advantages over hydrogen. Helium does not burn as hydrogen does, nor does it combine with other elements to harm metal or fabric.
Thrust is the force that moves an airship through the air. Airships usually obtain thrust by means of engines and propellers similar to those used on airplanes. These are often located in gondolas or cars that are suspended from the hull. The gondolas are called power eggs.
The crew controls an airship by means of fixed and movable surfaces, usually at the stern or rear. These surfaces look like the rudder and elevators of an airplane and work in the same general way that they do.