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Meeting	ACGS Committee Meeting 114 - Cleveland, Ohio - October 2014
Agenda Location	4 GENERAL COMMITTEE TECHNICAL SESSION 4.2 Government Agency Summary Reports 4.2.1 DLR 4.2.1.1 DLR
Title	DLR
Presenter	Klaus-Uwe Hahn
Available Downloads*	presentation
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Abstract	During the last two years the Department of Flight Dynamics and Simulation of the DLR Institute of Flight Systems carried out three different flight experiments in the frame of its aerospace research activities. The experiments were performed using DLR’s test aircraft ATRA (Advanced Technologies Research Aircraft) which is based on an Airbus A320 twin engine aircraft with a wing span of 34.1m and an MTOW of 75.5 tons. The executed flight experiments briefly introduced in the General Committee Technical Session are: OPIAM (Online Parameter Identification for Aerodynamic Modelling) This project deals with innovative methods that permit identification of the aerodynamic properties of an aircraft while in flight. During the experiment the DLR test pilots executed a series of complex maneuvers with ATRA to stimulate the aircraft dynamics. The measured and recorded flight test data were used to improve the accuracy of the flight dynamics model on-line. This will be an important tool for accelerating flight testing and certifying new aircraft. During flight testing decisions can be made on the extension of the test envelope of the aircraft based on the comparison of expected and identified aerodynamic coefficients respectively relevant model parameters, e.g. stability derivatives. Furthermore the computer model created on-line and based on the flight test data is needed for flight simulators and to design flight control systems. Two different approaches have been investigated. Method one works in the frequency domain and can be applied to linear systems. Method two is for non-linear systems and operates in the time domain. EPEVA (Energiebasiertes Pilotenunterstützungssystem für das präzise Einhalten vertikaler Anflugprofile, English: Energy-Based Pilot Assistance System for Precise Adherence to Vertical Approach Flight Profiles) EPEVA is a newly developed DLR pilot assistance system which helps pilots to execute quiet approach flights that are precise and safe, and also reduce fuel consumption. Therefore, a pilot must adhere precisely to a sequence of actions and aircraft configuration changes calculated in advance for the landing phase. Knowing only the reference wind at the airport and at the actual aircraft position an offline planning is executed predicting the position for initiating the decent (Top of Decent) for an approach with minimum thrust levels and without the use of airbrakes. During the approach an online correction is performed continuously to adapt the points of aircraft configuration changes (speed settings, flaps extension, gear deployment) considering the available wind information collected onboard the aircraft on the previous approach path. Before the flight experiment many tests have already been conducted in the DLR full flight simulator AVES (Air VEhicle Simulator). WEAA (Wake Encounter Avoidance and Advisory system) When in flight, aircraft generate turbulence behind them known as wake vortices, which can affect the air traffic that follows. The Institute of Flight Systems has tested a wake turbulence warning system in flight experiments using its ATRA and Falcon research aircraft. The Falcon 20E with a maximum weight of 12 tons was used to be the wake vortex generator and ATRA (A320) having a maximum weight of about 75.5 tons was the wake encountering aircraft. This arrangement allows ATRA flying into the vortices of the Falcon without endangering aircraft and passengers. The WEAA system can forecast potentially dangerous wake turbulence using just the positional data and weather information from a preceding aircraft. The system calculates the distance and the time to the predicted wake conflict. The computed wake conflict information for pilots of the encountering aircraft (ATRA) is integrated in the aircraft’s navigation display (ND). The calculations take into account the wind and the atmospheric conditions, using software developed by the DLR Institute of Atmospheric Physics. The function and the accuracy of the wake turbulence predictions were demonstrated with flights directed into the wake vortices. To enable the pilots to hit the wake weather conditions providing contrails were required. Although, the ATRA is much heavier than the DLR Falcon each vortex encounter was clearly noticeable. The predicted and the real encounter position and point in time were compared in the flight test data analyses being a measure of the prediction quality.