Estimation of the structural weight of an Unmanned Combat Aerial Vehicle (UCAV) during conceptual design has proven to be a significant challenge mainly due to its unconventional configuration. We investigate development of a customised approach for structural weight estimation of UCAV based on statistical weight of the manned fighter’s components by applying minor modifications on weight formulations of fuselage, wing, empennage, power plant and landing gear. The modifications are applied by considering the corresponding differences between manned fighters and UCAVs such as manned requirements and mission variances. Some new empirical formulas for estimating the weight of UCAV’s components are proposed. Results for the empty weight estimation are validated against actual values of some well-known UCAVs. Moreover, the structural weight is validated against the benchmark UCAV case studies. The results show that the ratio of structural to takeoff weight for UCAVs is approximately between 20% to 10%. Finally, a generalised equation is developed for estimating the structural weight of UCAVs in conceptual design phase.

Unmanned Combat Aerial Vehicles (UCAVs) are believed by many to be the future of aerial strike/reconnaissance capability. This belief led to the design of the UCAV 1303 by Boeing Phantom Works and the US Airforce Lab in the late 1990s. Because UCAV 1303 is expected to take on a wide range of mission roles that are risky for human pilots, it needs to be highly adaptable. Geometric morphing can provide such adaptability and allow the UCAV 1303 to optimise its physical feature mid-flight to increase the lift-to-drag ratio, manoeuvrability, cruise distance, flight control, etc. This capability is extremely beneficial since it will enable the UCAV to reconcile conflicting mission requirements (e.g. loiter and dash within the same mission). In this study, we conduct several modifications to the wing geometry of UCAV 1303 via Computational Fluid Dynamics (CFD) to analyse its aerodynamic characteristics produced by a range of different wing geometric morphs. Here we look into two specific geometric morphing wings: linear twists on one of the wings and linear twists at both wings (wash-in and washout). A baseline CFD of the UCAV 1303 without any wing morphing is validated against published wind tunnel data, before proceeding to simulate morphing wing configurations. The results show that geometric morphing wing influences the UCAV-1303 aerodynamic characteristics significantly, improving the coefficient of lift and drag, pitching moment and rolling moment.

The ever-changing battlefield environment, as well as the emergence of global command and control architectures currently used by armed forces around the globe, requires the use of robust and adaptive technologies integrated into a reliable platform. Unmanned Combat Aerial Vehicles (UCAVs) aim to integrate such advanced technologies while also increasing the tactical capabilities of combat aircraft. This paper provides a summary of the technical and operational design challenges specific to UCAVs, focusing on high-performance, and stealth designs. After a brief historical overview, the main technology demonstrator programmes currently under development are presented. The key technologies affecting UCAV design are identified and discussed. Finally, this paper briefly presents the main issues related to airworthiness, navigation, and ethical concerns behind UAV/UCAV operations.