Junkers Patent No. 253788
Junkers patent specification No. 253788 - often called Junkers flying wing patent in the literature - is a patent for the design of aircraft , filed by Hugo Junkers on February 1, 1910 and published by the Imperial Patent Office on November 14, 1912 . The original title of the patent reads glider with hollow bodies that are used to hold parts that do not generate lift .
In the patent, Junkers describes, among other things, instead of the braced, braced, thin wing that was customary at the time, a cantilever , non- braced wing with a thick profile as the ideal aircraft structure . The patent and its implementation by Junkers in practice from the Junkers J 1 to the Junkers G 38 were trend-setting for the entire aviation technology .
Although the patent is seen in many publications as a guide to a flying wing aircraft , the fact that Junkers ultimately describes a flying wing aircraft in the patent is doubted by other sources.
Content of Scripture
The first handwritten notes from Junkers dated December 3, 1909 still include the heading About a physical design of the wings . The final patent specification, however, bears the title glider with hollow bodies serving to hold parts that do not generate lift , which is misleading because obviously not only a glider is described because of the engines shown.
Based on the approach to further improve the "ratio of load capacity ( lift ) to driving resistance", Junkers developed his concept in the patent specification to accommodate "non-load-bearing parts of the aircraft as well as persons and payloads to be carried in cavities", which "also provide lift with the lowest possible driving resistance" produce. To this end, he suggests cavities whose “upper and lower boundary surfaces have the well-known curved shape that is favorable for aerofoils”. In particular, he proposes this cavity construction for the “ wing ” itself in order to accommodate the support structure of the wing inside the wing. In addition to the wing struts, it is also planned to accommodate engines and tanks in the thick wing.
In the patent drawings, two front views, a partial plan view, and several sections or side views are shown. A reconstruction of the dimensions and the wing outline (see illustration) on the basis of the size of a person drawn provides a wingspan of 15 to 16 m and a wing depth of 4.5 to 4.8 m.
The multiple trapezoidal shape of the reconstructed wing could also be found a little later on Junkers' wind tunnel models. The hand drawings still preserved suggest that in addition to the actual glider version, up to three other motorized versions were possibly planned:
- with two lag screws
- with two pressure screws
- with two tension and pressure screws each
According to the patent drawings, the propulsion should be done by opposed piston motors housed in the wings . The flowing transition between wings and fuselage is strongly reminiscent of the blended wing body concept that is used again today in various projects .
Flying wing?
Although the principle drawings of the patent specification do not show any tail units, some sources doubt that Junkers really represented a flying wing design. Rather, z. According to Pawlas, for example, it can be assumed that the designation flying wing patent, which only became more and more naturalized in the 1930s, takes up something for the Junkers aircraft that was not mentioned at all in the patent application.
From the text of the application, however, the actual intention can be inferred, namely all parts of the aircraft that do not contribute to lift and cause drag, such as e.g. B. engines, fuel tanks, struts, etc., to be removed from the air stream and to relocate them in a correspondingly shaped thick wing with large cavities. Tail units and other stabilization or control organs are not mentioned. If the patent had specifically targeted the flying wing, this information would have been essential. The conclusion is that the patent did not describe a specific new type of aircraft (flying wing), but only a component of an aircraft, namely the wings.
Practical implementation of the patent
Already in his first airplane, the experimental J 1 , which was built from September to December 1915 to prove the usefulness of the metal construction, Junkers consistently put the thick wing concept into practice. In contrast to the otherwise common double-deckers of that time, the cantilevered middle decker managed without any tension. In his project J.1000 from the early 1920s, Junkers' idea of the use of his thick grand piano is reflected even more strongly . The design, often incorrectly referred to as flying wing, showed a duck plane with a wingspan of 80 m, in which both the 100 passengers and the four motors in the wing were accommodated. This concept, but with a conventional tail unit design, was then implemented in practice by Junkers in the two G 38s that were built . Since the concept of a wing, in which all the elements causing the resistance are integrated, is a prerequisite for a meaningful implementation of a flying wing design, all such constructions have been designed to this day.
Historical background
The experiments of his Aachen professor colleague Hans Jacob Reissner with a conventional duck plane, which, however, used corrugated aluminum sheets already supplied by Junkers instead of the usual fabric-covered wings, can serve as motivation for Junkers' preoccupation with aerodynamic issues . In the early days of aviation, thin, braced and braced wings were the usual structural design of the airframe. Junkers was the first to have his idea patented, but around 1910 proposals for the use of a thick cantilevered grand piano appeared almost simultaneously, but independently of one another.
In 1911 , Paul Járay suggested in the “Österreichische Flug-Zeitschrift” to compare the forehead resistances of a wire-braced monoplane with those of a monoplane with a thick, non-braced structure, the wing struts of which should only be in the wing. Járay calculated a drag reduction of 45% for the latter configuration.
Also in 1911 was by the French aircraft designer Léon Levavasseur the Airplane Antoinette Monobloc designed and built. The aircraft was intended for participation in the Concours militaire 1911 and was described in detail in the French aviation magazine "l 'Aérophile" in the edition of January 15, 1912. The cantilevered low-wing aircraft had a profile around four meters deep and 0.7 meters thick at the wing root, and here, too, all struts were placed in the wing. Only one flight could be carried out because the construction had too little directional stability.
literature
- Hugo Junkers: Glider with hollow bodies used to hold parts that do not generate buoyancy. Patent Specification - No. 253788 - Class 77h. Group 5. Patented in the German Empire on February 1, 1910. , Imperial Patent Office, Berlin November 14, 1912
- Günter Schmitt: Hugo Junkers and his aircraft , transpress VEB Verlag für Verkehrwesen, 1988, ISBN 3-344-00303-8
- Wolfgang Wagner: The Junkers F13 and its forerunners , Leuchtturm Verlag, Konstanz 1976, ISBN 3-88064-015-7
Individual evidence
- ↑ a b Patent from Hugo Junkers : Glider with hollow bodies used to hold parts that do not generate lift.
- ↑ Bracing: A construction in construction or vehicle construction in which stability or elasticity is achieved by components under mechanical tension, such as ropes or wires that absorb tensile forces .
- ↑ Ludwig Bölkow (Ed.): A century of aircraft: History and technology of flying , VDI, Düsseldorf 1990, ISBN 978-3-642-95776-5 ; P. 26
- ↑ The big wing on the junkers.de page
- ↑ a b c Karl R. Pawlas: The first flying wing ?, Aviation Lexicon, Article ID: 9607-100-1
- ↑ Günter Schmitt: Hugo Junkers and his aircraft , p. 19 "... it was neither a flying wing nor a glider ..." ("... it was neither a flying wing nor a glider ...")
- ↑ Illustration of the patent specification ( Memento of the original dated July 4, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ To the big Junkers grand piano
- ↑ Junkers.de media library: The Reissner Ente , video about the Reissner Ente
