550 Pure Invention? – The Lamella Halls of the Aviation Pioneer Hugo Junkers <strong>2015</strong> ¥ 6 ∂ 13 On the partially rough terrain, the modular unit-construction system offered great advantages. In some cases, the lamellae and purlins were transported into remote regions using pack animals (ill. <strong>11</strong>). Following the success of this initial project, the first segmental-arch roof with tension rods as well as a multibay form of construction, consisting of three round-arch roofs, were erected – again on the company’s own works site. Smaller commissions in the Dessau area followed, such as the roof over the dining hall of a well-known hotel in the town centre and the outer enclosure of a bolt factory in Finsterwalde. Marketing the product The end of the patent dispute in 1928 and the engagement of the engineer Wilhelm Klingenberg at the same time as head of the steel construction department mark the beginning of the worldwide proliferation of Junkers halls. Klingenberg implemented the change from Z- and S-section to C-section lamellae (ill. 9), a modification that clearly simplified the manufacturing method because the new form could be pressed in a single process (ill. 10). Around 1930, wind-tunnel investigations and further loading tests led to a final modification of the lamella geometry, in which the transition from shaped cross-sections to flat metal junctions by means of a stamped knuckle detail became more pronounced (ills. 13, 16). At the same time, the standardization of the halls proved to be a decisive factor for their economic success. Klingenberg developed the structures into products that clients could order as finished objects. Modular design and flexibility nevertheless allowed the creation of many different forms. The halls were offered in various sizes, delivered and, where required, erected by the company as well. The first customers in other European countries were quickly found, too. In the case of Britain, not only the finished products were sold; licence and patent rights 14 were granted for the manufacture of the halls as well. This led to a situation where a large number of halls were developed in that country in slightly varying forms of construction. Further contracts followed in Brazil, Venezuela and even New Guinea, where the constructional elements were flown in with planes belonging to the Junkers concern (ill. 6). The halls today In all, roughly 170 halls and roofs were constructed according to the Junkers system, <strong>12</strong>0 of which were by the British licence holder. Only an incomplete picture can be drawn of the actual number and the present state of the surviving halls, however. As part of a current research project at the University of Technology in Munich supported by the Meitinger Foundation, a full mapping of the structures is being attempted – at least those built in Germany. The motivation for this were the halls standing on the former military airport in Oberschleissheim outside Munich, which are now used by aero clubs (ills. 13, 16). The structures are in a multibay form of construction and were built with lamellae 2.75 metres long. The three arched roofs were lined up next to each other and have an effective floor plan approximately 130 ≈ 30 m in size. The halls are listed structures protected by conservation order, although one of the three arched sections of the eastern hangar was lost some decades ago, destroyed during the war, reduced in size or removed after it had collapsed. The others are in a critical state. The halls that are still standing are being analysed with modern methods as a basis for their retention and rehabilitation. 15 13,16 Hangar at former military airport in Oberschleissheim near Munich (condition in <strong>2015</strong>). Axometric drawing of arched roof with linking framework to adjoining arch; view into hall with lateral framed structure (in foreground) 14 Indoor riding arena in Connewitz, Leipzig, with frame structure at sides, 1930; destroyed in 1943 15 Station hall in São Paolo, ca 1935
16 ∂ <strong>2015</strong> ¥ 6 Discussion 551