The concept of tiltrotor aircraft has been around for over seventy years, but it was not until the last decade that the advancement in Unmanned Aerial Vehicle (UAV) technology has made them a viable option. Although the design requirements of such UAV are complex and require careful consideration, the potential benefits are significant. Motivated by their potential capabilities, this paper aims to present a complete procedure for designing an electric tiltrotor UAV that incorporates the attributes of both fixed and rotary wing aircraft, including all necessary mathematical formulations. The paper explores the diverse aspects of the design and analysis of tiltrotor UAVs, from conceptual, preliminary, and detail design to aerodynamics, performance, and stability analysis. The detailed weight analysis is performed using six different methods from different references to assess their applicability for use with electric tiltrotor UAV. After designing and selecting the UAV components, an iteration process is performed to check and resize the estimated design parameters.