With advanced control, estimation and simulation requirements in unmanned aerial systems comes the need for sophisticated aerodynamic models. This paper reviews two common means for establishing such models; numerical design tools and wind tunnel testing, by presenting strengths and potential problems, in a "lessons learned"-manner. As a case study throughout the paper, a six degrees-of-freedom aerodynamic model of the Skywalker X8 fixed-wing unmanned aerial vehicle is presented.

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MEMS (micro-electro-mechanical system)-based inertial sensors, i.e., accelerometers and angular rate sensors, are commonly used as a cost-effective solution for the purposes of navigation in a broad spectrum of terrestrial and aerospace applications. These tri-axial inertial sensors form an inertial measurement unit (IMU), which is a core unit of navigation systems. Even if MEMS sensors have an advantage in their size, cost, weight and power consumption, they suffer from bias instability, noisy output and insufficient resolution. Furthermore, the sensor's behavior can be significantly affected by strong vibration when it operates in harsh environments. All of these constitute conditions require treatment through data processing. As long as the navigation solution is primarily based on using only inertial data, this paper proposes a novel concept in adaptive data pre-processing by using a variable bandwidth filtering. This approach utilizes sinusoidal estimation to continuously adapt the filtering bandwidth of the accelerometer's data in order to reduce the effects of vibration and sensor noise before attitude estimation is processed. Low frequency vibration generally limits the conditions under which the accelerometers can be used to aid the attitude estimation process, which is primarily based on angular rate data and, thus, decreases its accuracy. In contrast, the proposed pre-processing technique enables using accelerometers as an aiding source by effective data smoothing, even when they are affected by low frequency vibration. Verification of the proposed concept is performed on simulation and real-flight data obtained on an ultra-light aircraft. The results of both types of experiments confirm the suitability of the concept for inertial data pre-processing.

Autorotation is a challenging flight maneuver that involves highly coordinated control actions and competing constraints. It is generally recognized that pilot performance in autorotation may benefit from additional cues that improve decision-making as well as timing and coordination of control inputs. This paper describes the development and simulator testing of various pilot cues designed for autorotation. A set of discrete and continuous cues are defined to assist in the initiation and execution of various phases of the maneuver. Furthermore, a reachability cue is created to assist a pilot in rapidly evaluating the vehicle glide distance, thereby facilitating selection of a landing site. Piloted simulated flight trials are performed using various combinations of cues in both good and degraded visual environments. Results are evaluated through assessment of pilot workload as well as quantitative measures of landing performance with and without the cues. Overall, results and pilot evaluations show the potential utility of several of the cueing methods but point to specific improvements to them that may facilitate more precise pilot tracking as well as reductions in task workload.

Autorotation maneuvers in helicopters are generally performed in an emergency following some form of catastrophic mechanical or system failure. It is a complex maneuver to perform because the pilot is required to perform several tasks simultaneously and the timing of each of them needs to be precise. Workload can be high and the consequences of getting things wrong can be fatal. Following on from a series of studies that investigated the use of symbology presented on a Head-Up Display to try to assist a helicopter pilot to fly the autorotation maneuver more safely and accurately, this paper presents a pilot-in-the-loop flight simulation study to explore the use of haptic cueing to help the pilot maintain indicated air- and main rotor speeds. Various entry conditions to autorotation maneuver are assess via simulated flight trial at Liverpool's HELIFLIGHT-R full motion flight simulator. Subjective evaluation of the results show that the haptic cues are useful to pilots in terms of reducing the workload to perform a successful autorotation landing.