Sue Cheney, age 13, of Lansing, Mich., for her question:
What causes a blimp to operate?
Blimps are related to balloons and dirigibles and are indirectly kin to ships and floating rafts. A blimp has engines to guide it, and a balloon does not but both stay aloft for the same reason. A power driven ship floats for the same reason that a motorless raft bobs on top of the waves.
A blimp is operated by lifting force and thrusting power. Its lifting power is a whopping bag of gas that is 1ighter than the surrounding air. A balloon also lifts aloft because it is filled with lighter than air gases. These hulls of gas rise in the air for the same reason a cork floats on top of the water. They are pushed up because they are lighter or less densse than the air or water around them. This force is called buoyancy.
A high riding balloon must drift at the mercy of the breezes, but a blimp has Engines and propellers to steer it. The pilot can turn it and keep it on course in calm weather and against gentle winds. The Equipment that provides this guiding and thrusting power is in the car or gondola that hangs under the bulky, gas fi11ed hull. The pilot, the crew and the passengers also ride in the gondola.
The blimp is the simplest of the gas filled airships. Its hull is merely a rubbery skin with no supports, and when the gas is removed between flights it collapses. At first it was ca11ed a limp because on the ground it is as limp as a rag. This was in World War I, when British fliers used it to bomb Enemy cities. Their preferred model was the B type limp which quite naturally became known as the blimp.
The hulls of certain larger airships are supported with metal spines and nose cones. These semi rigid types also collapse between flights. The Entire hull of a huge dirigible, however. Is supported with a Metal skeleton. It keeps its shape whether empty or filled with lifting gas.
WE all have stopped to gape at a low flying blimp. The whole city spells out the letters of its advertising signs and watches its winking lights at night. Many of us have taken sightseeing tours in a blimp. But the duties of the bulky blimp axe not limited to signs and sights. Behind the scenes, it does faithful defense patrol to protect us in both war and peacetime.
Super aircraft and anti aircraft have made the blimp useless as a front line soldier. It can no longer bomb Cities, but it can guard ocean going convoys. On anti submarine patrol, it can spot Enemy subs and drop depth charges to destroy them. The blimp is also used to gather Weather data, and it has a glamorous role in our Early Warning System of defense.