query: subclass_of r23x-class airship
supports: Genocide is intentional action to destroy a people (usually defined as an ethnic, national, racial, or religious group) in whole or in part. The hybrid word "genocide" is a combination of the Greek word "génos" ("race, people") and the Latin suffix "-cide" ("act of killing"). The United Nations Genocide Convention defines genocide as "acts committed with intent to destroy, in whole or in part, a national, ethnic, racial or religious group". An airship or dirigible balloon is a type of aerostat or lighter-than-air aircraft that can navigate through the air under its own power. Aerostats gain their lift from large gas bags filled with a lifting gas that is less dense than the surrounding air.
  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. Significant amounts were first discovered in the United States and for a while helium was only used for airships by the United States. Most airships built since the 1960s have used helium, though some have used hot air. In general, a civilian is "a person who is not a member of the military or of a police or firefighting force", as defined by Merriam Webster's Dictionary. From the perspective of the U.S. Department of Defense, Chapter 18 of Title 10 United States Code refers to non-military law enforcement officers as civilians since they are employees rather than enlisted personnel, and also in order to distinguish itself from military police. In military and law enforcement slang, the term "Civies" or "Civvies" are often used to refer civilian population or civilian clothing. A rigid airship is a type of airship (or dirigible) in which the envelope is supported by an internal framework rather than by being kept in shape by the pressure of the lifting gas within the envelope, as in blimps (also called pressure airships) and semi-rigid airships. Rigid airships are often commonly called Zeppelins. World War I (WWI or WW1), also known as the First World War, or the Great War, was a global war originating in Europe that lasted from 28 July 1914 to 11 November 1918. More than 70 million military personnel, including 60 million Europeans, were mobilised in one of the largest wars in history. Over nine million combatants and seven million civilians died as a result of the war (including the victims of a number of genocides), a casualty rate exacerbated by the belligerents' technological and industrial sophistication, and the tactical stalemate caused by gruelling trench warfare. It was one of the deadliest conflicts in history, and paved the way for major political changes, including revolutions in many of the nations involved. Trench warfare is a type of land warfare using occupied fighting lines consisting largely of trenches, in which troops are significantly protected from the enemy's small arms fire and are substantially sheltered from artillery. The most famous use of trench warfare is the Western Front in World War I. It has become a byword for stalemate, attrition, sieges and futility in conflict. Military personnel are members of the armed forces. Usually, personnel are divided into military branches roughly defined by certain circumstances of their deployment. Those who serve in a typical large land force are soldiers, making up an army. Those who serve in seagoing forces are seamen or sailors, and their branch is a navy or coast guard . Marines serve in a marine corps. In the 20th century, the development of powered flight aircraft prompted the development of air forces, serviced by airmen. Designated leaders of military personnel are officers. These include commissioned officers, warrant officers and non-commissioned officers (NCOs). For naval forces, non-commissioned officers are referred to as petty officers (POs).
  military personnel are instructed to wear dog tags A semi-rigid airship or dirigible is an airship which has a stiff keel or truss supporting the main envelope along its length. The keel may be partially flexible or articulated and may be located inside or outside the main envelope. The outer shape of the airship is maintained by gas pressure, as with the non-rigid "blimp". Semi-rigid dirigibles were built in significant quantity from the late 19th century but in the late 1930s they fell out of favour along with rigid airships. No more were constructed until the design was revived by the Zeppelin NT in 1997. A Zeppelin was a type of rigid airship named after the German Count Ferdinand von Zeppelin who pioneered rigid airship development at the beginning of the 20th century. Zeppelin's notions were first formulated in 1874 and developed in detail in 1893. They were patented in Germany in 1895 and in the United States in 1899. After the outstanding success of the Zeppelin design, the word "zeppelin" came to be commonly used to refer to all rigid airships. Zeppelins were first flown commercially in 1910 by Deutsche Luftschiffahrts-AG (DELAG), the world's first airline in revenue service. By mid-1914, DELAG had carried over 10,000 fare-paying passengers on over 1,500 flights. During World War I the German military made extensive use of Zeppelins as bombers and scouts, killing over 500 people in bombing raids in Britain. The British R23X class of rigid airships were developed during World War I using the experiences gained from the 23 class , but only two of the planned four R23X class were built : R27 and R29 . Both were completed mid- 1918 , but just two - and - a - half months after entering service R27 was destroyed by fire in a hangar ; while R29 went on to become the most successful British wartime rigid airship , being the only one to meet enemy action . Because of Archimedes' principle, a lifting gas is required for aerostats to create buoyancy. Its density is lower than that of air (about 1.29 kg/m, 1.29 g/L). Only certain lighter than air gases are suitable as lifting gases. A blimp, or non-rigid airship, is an airship (dirigible) without an internal structural framework or a keel. Unlike semi-rigid and rigid airships (e.g. Zeppelins), blimps rely on the pressure of the lifting gas (usually helium, rather than hydrogen) inside the envelope and the strength of the envelope itself to maintain its shape. The term is sometimes also used to refer to the tethered craft properly known as moored balloons. While often very similar in shape, moored balloons have no propulsion and are tethered to the ground.
candidates: action aerostat aircraft airship army being blimp bombing clothing combination count craft department envelope fire flight force gas general german germany greek group history law member military personnel military police navy number out own person police population pressure principle propulsion quantity rate rigid airship suffix term title truss type war warfare western world zeppelin
answer: aircraft