Information: - The Rhon Mountains (German: "Die Rhon") are a group of low mountains (or "Mittelgebirge") in central Germany, located around the border area where the states of Hesse, Bavaria and Thuringia come together. These mountains, which are at the extreme southeast end of the East Hesse Highlands ("Osthessisches Bergland"), are partly a result of ancient volcanic activity. They are separated from the Vogelsberg Mountains by the river Fulda and its valley. The highest mountain in the Rhon is the Wasserkuppe which is in Hesse. The Rhon Mountains are a popular tourist destination and walking area. - The Wasserkuppe is a mountain within the German state of Hesse. The elevation, which is a large plateau formation, is the highest peak in the Rhon Mountains. Between the First and Second World Wars great advances in sailplane development took place on the mountain during the interwar period. Near the summit there is still an airfield used by gliding clubs and pilots of light aircraft. - The Pelzner Hang Glider was a simple , lightweight , low cost but strong hang glider built in Germany in 1920 , intended to make flying accessible to large numbers of young people . Variants competed with some success in the first two Rhon contests held on the Wasserkuppe . - Gliding is a recreational activity and competitive air sport in which pilots fly unpowered aircraft known as gliders or sailplanes using naturally occurring currents of rising air in the atmosphere to remain airborne. The word "soaring" is also used for the sport. - Hesse or Hessia (, Hessian dialect: "Hesse" ) is a federal state ("Land") of the Federal Republic of Germany, with just over six million inhabitants. The state capital is Wiesbaden; the largest city is Frankfurt am Main. Until the formation of the German Reich in 1871, Hesse was an independent country ruled by a Grand Duke (Grand Duchy of Hesse). Due to divisions after World War II, the modern federal state does not cover the entire cultural region of Hesse which includes both the State of Hesse and the area known as Rhenish Hesse (Rheinhessen) in the neighbouring state of Rhineland-Palatinate. - In geology and earth science, a plateau (or ; plural plateaus or plateaux), also called a high plain or tableland, is an area of highland, usually consisting of relatively flat terrain that is raised significantly above the surrounding area, often with one or more sides with steep slopes. Given the information, choose the subject and object entities that have the relation of 'subclass of'.
Answer:
pelzner hang glider , aircraft