Ulf Ringertz
DOI Number: N/A
Conference number: IFASD-2019-140
The design, analysis and structural testing of a new wing for a flutter wind tunnel model is considered. The aircraft configuration represents a modern light weight fighter configuration with external stores. A first test in the Transonic Dynamics Tunnel (TDT) at NASA Langley was performed in 2016 and the upcoming second test is planned for 2020. During the first test program, a large amount of static aeroelastic data was acquired both in air and heavy gas (R134a) and also some dynamic data. Flutter testing was also performed but only two flutter conditions were achieved before model damage. For the second test, a new wing structural design is being developed in order to allow flutter testing also without under-wing external stores and without significant mass balancing. However, in order to maintain sufficient structural strength, design optimization is required. The new design is to maintain the same strength as the first design tested but with much lower flutter dynamic pressure in transonic conditions. The strength requirements are considered using structural testing in combination with linear elastic finite element analysis. The design process has demonstrated that changing the composite layup will have a very significant influence on the predicted flutter dynamic pressure without loss of strength. By using a mix of glass-fiber weave with a few layers of uni-directional glass-fiber and tailoring of the fiber orientation, a sufficiently large reduction in flutter dynamic pressure can be obtained.