Grid fins are an attractive alternative to conventional control fins due to their aerodynamically very stable and very effective behaviour in the whole Mach number range and up to high angles of attack. Further advantages are low hinge moments and a low wing mass. Whereas grid fins are already applied for a few years in some Russian missiles, the European missile industry lacks approved and competitive methods for the design and optimisation of grid fins. In the frame of the DLR-project “High agile Missile” (HaFK) systematic investigations were carried out that allowed the calculation of the aerodynamic performance of an isolated grid fin according to the half empiric grid fin theory [1]. These investigations were also used to complete and modify this theory for the whole velocity range (subsonic, transonic, and supersonic speeds).
The newly developed software tool FastGRIDS allows the calculation of the aerodynamic forces induced by a grid fin on the basis of given geometric parameters (height, chord, span, pitch, and member thickness) and the required flow conditions. Furthermore, this tool allows the optimisation of principle configurations with the option to vary the optimising parameter according to the maximal lift to drag ratio of the grid fin.
The newly developed tool was also implemented in the DLR-internal developed TAU-code as a module [2]. Implemented as an actuator disc it allows the calculation of complete missile configurations with grid fins. With this method it was possible to reduce the total calculation time to 16% of the former run time [3].
Publications
[1] Belotserkovsky, SM, Odnovol LA, Safin, YuZ, Tylenev, AI, Frolov, VP, Shitov, VA: „Reshetchatye krylia“ (in English: „Lattice Wings“), Mashinostroenie, 320 p, Moscow, 1985 (in Russian)[2] Reynier Ph., Schülein E. “Incorporation of an Actuator Disc for Lattice Wing Modelling in an Unstructured Navier-Stokes Solver”, in: /New Results in Numerical and Experimental Fluid Mechanics IV, /edited by C. Breitsamter et al., Vol. 87, Notes on Numerical Fluid Mechanics and Multidisciplinary Design, Springer-Verlag, Berlin Heidelberg, 2004, pp.132-139. [3] Reynier Ph., Longo J.-M., and Schülein E., „Simulation of Missiles with Grid Fins Using an Actuator Disk,” /Journal of Spacecraft and Rockets/, Vol.43, No.1, Jan.-Feb.2006, pp. 84-91.