Runway conflicts pose a significant threat to continued safety in commercial aviation. In recent years, stakeholders have initiated a number of programmes dealing with the issue of runway incursions, with the majority adopting traditional advisory alerting techniques. In contrast, this work proposes the use of directive cockpit alerting, which provides both an alert of the conflict as well as guidance on which manoeuvre to conduct to clear the conflict. This article reports the findings of simulator trials that have been conducted to assess the effectiveness and acceptability of a directive alerting strategy within the context of runway incursions. Statistical analysis performed on the quantitative measures taken from the evaluations have shown that the directive mode of alerting leads to a higher probability of the crew performing the correct action when faced with an alert. This, together with overall participant acceptance of the directive alerting concept, is a strong indicator that the technique has the potential of providing a complete solution to the problem of runway incursions.

The ‘Ornicopter’ is a single-rotor helicopter without anti-torque rotor developed since 2002 at Delft University of Technology in The Netherlands. The Ornicopter’s principle is similar to the movement of a bird’s wing and is based on actively flapping the blades up and down while rotating them around a shaft to generate both the required lift and the propulsive force. The shaft torque is no longer needed and thus the anti-torque rotor is redundant. The present paper describes the basic principles of the Ornicopter’s forced flapping, discussing the feasibility of the Ornicopter concept with respect to the power required, performance, stability, and vibratory loads. On the one side it is shown that the Ornicopter has a similar power requirement to a conventional helicopter, as well as very similar longitudinal and lateral stability and controllability characteristics to a conventional helicopter. On the other side, the Ornicopter generates higher vibratory loads than in a conventional helicopter, and its performance is strongly limited by the stall effect.

This paper presents the development and testing through simulation of an integrated scheme for aircraft sub-system failure detection and identification (FDI) based on the artificial immune system (AIS) paradigm augmented with artificial neural networks. The features that define the self within the AIS paradigm include neural estimates of the angular accelerations produced by the abnormal conditions. The simulation environment integrates the NASA Generic Transport Model interfaced with FlightGear. A hierarchical multi-self strategy was investigated for developing FDI schemes capable of handling malfunctions of a variety of aircraft sub-systems. The performance of the FDI scheme has been evaluated in terms of false alarms and successful detection and identification over a wide flight envelope and for several actuator and aerodynamic surface failures. For all cases considered, the performance was very good, confirming the potential of the AIS paradigm augmented with the proposed neural network-based approach for feature definition to offer a comprehensive solution to the aircraft sub-system FDI problem.

A study was conducted on a GA(W)-1 wing in order to investigate the effect of testing inverted wings in ground effect at low Reynolds numbers. The wing was tested at a range of ground clearances and Reynolds numbers and results showed that the wing’s performance was dependent on both these parameters. Surface flow-visualisation and numerical simulation results highlighted the existence of a laminar separation bubble on the wing’s suction surface. The results also indicated that both the bubble’s length and the onset of separation were sensitive to ground clearance and Reynolds number. Attempts were made to minimise the wing’s Reynolds number dependency by using transition strips on the suction surface. The transition strip results highlighted the influence that a laminar separation bubble has on the overall performance of the wing and how its presence alters the force enhancement and reduction mechanisms on an inverted wing in ground effect.

The ability to repair battle damage in a helicopter tail drive shaft (TDS) caused by small arms fire is a very important capability. A successful repair will enable the helicopter to continue its mission or at least allow it to return safely to base. This paper describes assessment of conventional and novel repair techniques using riveted metallic patches to restore the balance and strength of a damaged TDS. Analytical approaches are provided for the design of the repair. Modal analyses indicated that the effect of repair on change of the natural frequency of the TDS was negligible. An experimental testing program was conducted to validate the proposed repair methods. It has been demonstrated that the proposed repair methods achieved sufficient balance restoration by a defined repair procedure, assuming the unbalance could not be measured during a repair in the field. The conventional thin, single aluminium sheet, riveted repair significantly restored static strength. However, it only gave a fatigue life of 15hrs, and thus the repaired shaft may only be used for limited time for a military mission. The improved thick, two-half aluminium shell, riveted repair had sufficient static strength and met the 100-hour fatigue requirement.

Collision-avoidance is a safety-critical requirement to operate UAVs in non-segregated airspaces. In case of communication problems between a UAV and the corresponding pilot-in-command, a technology is required onboard the UAV to implement a capability to detect and avoid collision-hazards even autonomously. After an introduction to the problem of developing a so-called sense-and-avoid system and its avoid-function, this work presents a solution in terms of algorithms to implement the above capability. To detect and resolve potential mid-air conflicts, a geometric deterministic approach has been utilised: an intruder is modeled trough a moving-ellipsoid and a four-dimensional approach in the time-space domain provides the solution. The approach makes use of kinematics information to detect potential conflicts and to provide actions for conflict resolution, such as speed-changes in intensity and/or direction. The proposed solution also enables the UAV to meet the applicable vertical and horizontal minima of separation and to comply with real-time constraints.