Support of icing flight tests by near real-time data analysis

Raab, Christian; Ohme, Per; Deiler, Christoph

doi:10.1007/s13272-017-0260-5

Cited by 4 publications

(3 citation statements)

References 15 publications

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“…During all flights with the SLD-ice shapes a telemetry link was used to send the data to a ground station. Several online system identification tools [22] were operated for monitoring the aircraft characteristics during the whole flight on ground with live data. This way the crew was informed about the current flight characteristics of the aircraft at any time via a direct radio link.…”

Section: Figure 6 Drag Polars Computed From Measurements As a Results Of Flight Test Manoeuvres: Clean Aircraft (Black) And Specific Sld-mentioning

confidence: 99%

Flight Characteristics with Different Supercooled Large Droplet Ice Configurations

Deiler¹

2021

Aeronaut. j.

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An evaluation of the effects of different ice configurations on the flight characteristics of a fixed-wing aircraft is presented. Within a joint research project of German Aerospace Center (DLR) and Brazilian aircraft manufacturer Embraer simulation models of three supercooled large droplet (SLD) ice configurations were developed for one Phenom 300 prototype. A specific flight test campaign with artificial SLD ice shapes on the aircraft was conducted to gather the relevant flight data. The simulation models for the different ice configuration were obtained by system identification, and specific results for the SLD-ice simulation models are provided. The analysis of aircraft characteristics was based on the results of these high-quality simulation models: the icing-induced changes of the flight performance characteristics evaluated by the interpretation of several parameters like thrust-to-weight ratio and specific excess power. The typical flight performance degradation was found for all ice configurations with different magnitude. The change of aircraft eigenmodes was investigated in detail by analysing the system matrix of the linearised models at a specific trim points. In addition, the diverse effects found for different ice configurations (App. C and SLD) are discussed and the change of root locus is analysed. Furthermore, ice-induced changes of the handling qualities are evaluated using numerical criteria of flying qualities standard “MIL-STD-1797 A”: no significant deterioration was found for the investigated ice configurations.

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Section: Figure 6 Drag Polars Computed From Measurements As a Results Of Flight Test Manoeuvres: Clean Aircraft (Black) And Specific Sld-mentioning

confidence: 99%

Flight Characteristics with Different Supercooled Large Droplet Ice Configurations

Deiler¹

2021

Aeronaut. j.

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“…The corresponding change of the aircraft drag coefficient for each ice case is given in Figure 5, for which the coefficients are calculated from the flight measurements [14]. The form of the drag polar is completely different in both ice cases; for the run-back ice, the drag increase at medium lift coefficients is smaller than for leading-edge ice, which shows a stronger curvature and consequently higher drag coefficient at comparable lift coefficients.…”

Section: Discussionmentioning

confidence: 99%

Facing the Challenges of Supercooled Large Droplet Icing: Results of a Flight Test Based Joint DLR-Embraer Research Project

Deiler¹,

Ohme²,

Raab³

et al. 2019

SAE Int. J. Adv. & Curr. Prac. in Mobility

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T oday's airplanes are well equipped to cope with most common icing conditions. However, some atmospheric conditions consisting of supercooled large droplets (SLD) have been identified as cause of severe accidents over the last decades as existing countermeasures even on modern aircraft are not necessarily effective against SLD-ice. In 2014, the new Appendix O to the certification regulations (FAR Part 25 / CS-25) had been issued to guarantee the safe operation of future airplane when encountering SLD conditions. But as the SLD topic is quite new for the majority of aircraft manufacturers and research institutes in a same way, DLR (German Aerospace Center) and Embraer established a joint research cooperation in 2012 to obtain a better understanding of the distinct influences of SLD-ice shapes on aircraft characteristics and to evaluate proper ways for future airplane certification under App. O. Furthermore, one additional scientific goal of the cooperation was to develop and test new tools for the in-flight monitoring of aircraft characteristics as well as the on-board identification of simulation models. During the 4 years of the project, a distinct way to better understand icing-induced degradations on a specific aircraft was followed: first, data of the clean aircraft was gathered in flight test to identify a dynamic simulation model as base for the subsequent evaluations. Second, data of test flights with artificial App. C ice configurations were analyzed and used for the development of distinct modifications of the base aircraft simulation model; a first evaluation of the icing-induced changes of aircraft characteristics was conducted. Third, after the generation of SLD-ice shapes, wind tunnel testing and flight clearance, a second flight test campaign with these artificial SLD-ice shapes delivered the data for an additional model modification and identification. The results of the final data and model evaluation provide the observable degradation of SLD-ice in flight, which is well comparable to results obtained from the App. C ice configurations.

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“…Both tools further demonstrated their capabilities of successful flight-test support during high-risk icing flights where the online system identification results were required to continuously monitor the test aircraft's performance and control characteristics [28].…”

Section: Online System Identification Toolsmentioning

confidence: 99%

Retrospective and Recent Examples of Aircraft and Rotorcraft System Identification at DLR

Deiler

Mönnich

Seher-Weiß

et al. 2023

Journal of Aircraft

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Aircraft system identification has a five-decades-long tradition at German Aerospace Center (DLR). Over the last two decades, the research covered various topics related to system identification of fixed- and rotary-wing aircraft, nonconventional applications and atmospheric effects, the development of new flight-test procedures for system identification purposes, and specific aircraft model enhancements and corresponding parameter estimation. Comprehensive tools were developed that support this research and can be applied to a variety of different problems and types of vehicles. The paper starts with a short description of the different system identification methods used at DLR and the corresponding tools. The discussion of flight-test procedures and maneuver design as well as sensor fusion and flight-path reconstruction provides information on how to optimize the flight tests for system identification and to arrive at a consistent flight-test database. The examples for fixed-wing aircraft provide information on identification including abnormal conditions such as icing and interaction with atmospheric disturbances as well as modeling of structural mechanics and loads. The identification of high-order rotorcraft models that account for rotor and engine dynamics and even structural modes is discussed, and the identification of rotor mast moments as well as the identification of non-physics-based models and their integration into physics-based models are also covered. A final section shows that system identification can also be used to derive models for gyroplanes and parachutes as well as to derive control equivalent turbulence input models and to estimate complex wind field geometries. Thus, a broad overview of possible applications of system identification is given.

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Support of icing flight tests by near real-time data analysis

Cited by 4 publications

References 15 publications

Flight Characteristics with Different Supercooled Large Droplet Ice Configurations

Flight Characteristics with Different Supercooled Large Droplet Ice Configurations

Facing the Challenges of Supercooled Large Droplet Icing: Results of a Flight Test Based Joint DLR-Embraer Research Project

Retrospective and Recent Examples of Aircraft and Rotorcraft System Identification at DLR

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