The first use of honeycomb structures for structural applications had been independently proposed for building application and published already in 1914.[11] In 1934 Edward G. Budd patented a welded steel honeycomb sandwich panel from corrugated metal sheets and Claude Dornier aimed 1937 to solve the core-skin bonding problem by rolling or pressing a skin which is in a plastic state into the core cell walls.[12] The first successful structural adhesive bonding of honeycomb sandwich structures was achieved by Norman de Bruyne of Aero Research Limited, who patented an adhesive with the right viscosity to form resin fillets on the honeycomb core in 1938.[13] The North American XB-70 Valkyrie made extensive use of stainless steel honeycomb panels using a brazing process they developed.