Review of uncertainty of the flow over low sweep lambda wing unmanned combat air vehicles (UCAV)

Abstract

Unmanned Combat Air Vehicles (UCAVs) are future aircraft without the involvement of human pilot. UCAV not only have to endure for stealth but also maneuverability. Therefore, the UCAV configurations are tailless low sweep lambda wing configurations. UCAVs planform is encountered by the highly unsteady and uncertain flow behavior. This review article provides series of investigations for the unsteadiness and uncertainty of the flow topology above the surface of different low sweep lambda wing UCAV configurations. The experimental and computational results of the unsteadiness and uncertainties of the flow topology for the low sweep lambda UCAVs by various researchers are investigated. Further. these configurations are categorized based on addressed problems and the performance matrices used to evaluate the numerous UCAV configurations. Depending upon specific existing studies reflected in this review article: it was observed that aerodynamic stability derivatives are very sensitive to the flow topology above the wing surface. This review article also indicates that the unsteadiness and uncertainties of the flow topology need to be mitigated at higher AOA so that the aerodynamic stability derivatives are more consistent and predictable for the low sweep Lambda wing configurations. The sample investigations on MULDICON AVT251 has shown that the unsteadiness and uncertainties of the flow topology are mitigated, and the pitching moment coefficient becomes consistent and predictable for angle of angles of attack range of 10 degrees to 20 degrees for which the pitching moment coefficient was highly inconsistent and unpredictable for the previous low sweep UCAV configurations. The new and innovative methods to resolve unsteady and uncertain flow over the surface of the UCAV can assist researchers to improve and understand the current methodologies for further variation.