Fins play a vital role in improving the directional stability of aerial vehicles. However, airships are characterized by an inherent directional instability due to undersized fins. In this paper, a systematic approach to the design of airship fins is proposed. A constrained optimization problem is formulated to identify the optimal location, span, and chord of the airship fins. A semi-empirical aerodynamic model is used to formulate the objective function that represents the directional instability of an airship. The validity of the numerical solution acquired by minimizing the objective function with other design constraints is shown through a series of wind tunnel experiments. The result of the experiments confirms that the outcome of the fin optimization problem exhibits the best performance among the test cases, which validates the proposed methodology for designing the fins of the airship.

Modelling of dynamics of an airship is essential in the prediction of the flight characteristics, stability analysis and the design of control laws for autonomous operation. In the dynamics model that was proposed by Ashraf and Choudhry [1], deviations were observed between the simulation results and the validation data since the lengths and areas associated with the calculation of aerodynamic coefficients were not normalised. This paper documents the revisions proposed to the incorporation of semi-empirical aerodynamic estimation technique in the dynamics modelling of an airship as well as the normalisation of aerodynamic coefficients. Simulations are performed on the revised airship dynamics model and are compared with the simulation results of preceding models. A satisfactory agreement is seen between the revised model and the validation data, both in terms of magnitude and trends.

Electric unmanned aerial vehicles consume a significant portion of their stored propulsion energy in gaining altitude. The analysis of shortfall in cruise range as a function of climb altitude confirmed that, if the energy required for climbing is conserved, then cruise range of the UAV would improve significantly. In this paper, we present a conceptual design of a High Endurance Relocatable Crewless Aircraft on Reconnaissance Aerostat, a novel system that would enable electric UAVs to operate continuously from an aerostat deployed at the cruising altitude of the UAVs. The three subsystems of HERCARA - the aircraft carrier (aerostat), aircraft and the ground station are also discussed.

This paper presents a control architecture for reference tracking of a small autonomous airship with input constraints. Nonlinear receding horizon optimization is used in order to generate a reference trajectory for the low-level controller to track. A simplified lateral dynamics model for an airship is also presented in this paper to be used for prediction. To investigate the efficacy of the proposed control algorithm, it is then implemented on a simulation platform and tested on a 6-degrees-of-freedom airship model to track a straight line and circular trajectory in the presence of wind disturbance. The simulation results indicate that the proposed planner generates a feasible trajectory for the low-level controller to track. A significant improvement in the tracking performance of the airship is also seen by the introduction of the planner.

Airships have been revived towards the end of 20 th century. Airships have found numerous applications other than sightseeing and advertising. Autonomous control of airships is one of the areas where scientific research and development has gained tremendous attention in the recent years. This paper describes a methodology to simulate both the dynamics and control of an airship using virtual platforms-ROS and Gazebo. Gazebo is used to model the dynamics of the airship and ROS is used to develop a motion control algorithm.

This paper presents a novel method for the design of a small unmanned airship with stability considerations. Conventional design methods for airship envelope require the structure weight including the fin weight to be fixed before determining the envelope size. One of the shortcomings of the traditional methodology is that the weight budget of the fin drives the fin design. In contrast to the conventional design methods, our method estimates the envelope size and the fin weight budget simultaneously. Our approach also shows how an airship fin could be optimized to improve directional stability. The design of a small unmanned airship is also discussed in this paper to demonstrate the methodology.