Failure detection, identification and reconfiguration - applications for a modular iron bird

The permanently fast growth of airline market must not lead to rising numbers of accidents. To improve aircraft safety, pilot workload has to be reeduced especially in critical situations. This paper describes the system architecture of a new test rig to evaluate the iron bird to demonstrate its potential deals with the evaluation of a solution for reconfiguration: elevator failures are compensated by using a new Trimmable Horizontal Stabilizer Actuator concept with higher dynamics, which can be integrated in modern airliners. The test rig enables research on the interactions of different subsystems for failure detection, identification and reconfiguration of the modified controller by using Hardware-in-the-Loop tests of flight control actuators in combination with pilot evaluations in a cockpit simulator

Wake Encounter Flight Control Assistance Based on Forward-Looking Measurement Processing

Weather dependent delays, incidents and even accidents play an important role in aircraft operation. Any airplane is subject to air motion. Thus, turbulence is an important parameter in aeronautics. The phenomena which are summarized as gusts and turbulence strongly affect the passenger comfort and the safety of aircraft. Especially the turbulence caused by the wake of other aircraft can cause undesired motions mainly roll and vertical aircraft and support the pilot to carry out his control task. With the aid of specific controllers such vortices can be safely encountered even if the required control power temporarily exceeds the aivailable capacity. Aircraft equipped with such a controller will be less affected by unforeseen wake vortex encounters or even will be able to follow another aircraft closer than authorized by the current separation distances without any compromise concerning safety. A very promising concept for wake vortex disturbance alleviation is the fee-forward disturbance compensation. The application of such an approach requires the accurate determination of the flow disturbance to calculate the necessary counter measures in terms of required control activities. Thus, the disturbance flow determination plays an important role and needs to be investigated thoroughly. Modern LIDAR technology has the potential to measure the flow filed in front of the aircraft and to provide the required disturbance information in advance before it affects the aircraft. The final goal of the DLR approach is the development of an Integrated Ride and Loads Improvement System (IRLIS) which is able to cope with the whole frequency range of atmospheric flow disturbances relevant for aircraft operation. The presented paper will summarize the status of the work performed during the last years and the current activities

Wake Turbulence Evolution and Hazard Analysis for a General Aviation Takeoff Accident

Wake turbulence is commonly a commercial aviation topic involving relatively heavy transport aircraft. However, wake turbulence is also safety relevant for business and general aviation flight operations. A detailed analysis has been conducted for a specific accident involving two aircraft of the wake turbulence category light. A four-seat aircraft with one ton maximum takeoff weight took off behind a biplane with 5.5 tons maximum takeoff weight. This led to a fatal accident. Based on available information and several assumptions the wake turbulence aspects for the specific accident scenario have been assessed. The roll axis was the dominating factor in this case. Accordingly, the wake induced rolling moment was analyzed and related to the assumed available roll control power. Furthermore, the wake vortex behavior was simulated and analyzed in detail. The results indicate that wake turbulence can be considered to be the cause for the accident. The theoretical results and the conclusions regarding the accident are also supported by the results of flight tests, which were conducted in the context of the accident investigation

Design Space Exploration Study and Optimization of a Distributed Turbo-Electric Propulsion System for a Regional Passenger Aircraft

Electric propulsion systems are considered as one possibility to reach the ambitious goals of the European Union’s Flightpath 2050 with regards to greenhouse gas emissions and noise. It has been claimed in several publications that Distributed Electric Propulsion (DEP) offers significant improvement in aerodynamic efficiency and thus a reduction in structural weight of the wing and noise emissions as well as additional degrees of freedom concerning flight control. To not outweigh those advantages by heavier drivetrains, the components within the electric propulsion system have to be extremely lightweight, efficient and reliable at the same time. The German nationally funded project SynergIE evaluates DEP for a 70 PAX regional reference aircaft with two (SE-2), six (DEP-6) and twelve (DEP-12) propulsion units with a turbo-electric drivetrain layout. This study aims to quantify the effect on the specific block fuel consumption for the different numbers of propulsors based on Top Level Aircraft Requirements (TLARs). The approach contains a coupled electric drivetrain system model which is based on physically derived, analytical models for each component linking specific subdomains, e.g., electromagnetics, structural mechanics and thermal analysis. A genetic algorithm is applied to optimise the key performance indicators (KPIs) of the electric system, before the results are fed back to the aircraft sizing process. It has been identified that constraints such as installation space or architectural decisions such as the number of propulsors have significant influence on the drivetrain weight and efficiency and interact with the whole aircraft sizing process, esp. with reference to nacelleweight and drag and thus the block fuel consumption. The study shows that the DEP-6 and DEP-12 project aircraft both have a potential of reducing the specific block fuel consumption by approx. 4.2% and 5.8% respectively in case of direct driven propellers, while for a geared-drive scenario a total reduction of up to 7.6% in case of DEP-6 and 8.5% in case of DEP-12 is possible, all compared to the direct-driven baseline (BSL) aircraft SE-2