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Modular Platform for Aircraft Flight and Ground Operation

Periodic Reporting for period 1 - OPeRATOR (Modular Platform for Aircraft Flight and Ground Operation)

Reporting period: 2018-10-01 to 2020-03-31

The OPeRATOR project will develop a Software library that is able to:

1) Make a virtually integrated aircraft model fly by appropriately integrating flight physical aspects,
2) Virtually operate it in a realistically modelled environment and
3) enable the analysis of over-all and individual system behavior during user-specified virtual missions.

The software library will be implemented in the Modelica language and capabilities will be provided to interface the models developed into other analysis tools.

The OPeRATOR project allows to numerically assess the benefits of new systems and component technologies based on realistically simulated aircraft operations. In this way, performance improvements can be actually quantified, both in ideal as well as off-nominal conditions. The analysis results can be used in an aircraft over-all design optimization, as well as in detailed assessment of system performance in discipline-specific analyses. In this way, the developed model library and models will allow for further improvement of aircraft regarding environmental impact, efficiency, and even safety. This in turn will help the European industry to develop more fuel efficient, cleaner and safer aircraft, improving competitiveness of aircraft manufacturers and suppliers.

Over-all objectives of the project are:
1) To develop parametrizable models of in-flight and on-ground aircraft operations, covering all mission profiles across multiple aircraft platforms. In order to take full advantage of this modelling and analysis capability, it is necessary:
2) To seamlessly integrate these models into the MISSION aircraft and system trade-off platforms developed by the Clean Sky 2 MISSION consortium, as well as to interface them with available detailed models of airport environment and ATC platforms.
As a first step, requirements for the model library have been defined, as well as interfaces to the Mission aircraft design environment and a set of use cases that are to be addressed. These use cases include actuator force-fight in flight, actuator failure cases, rejected take-off scenarios, mission profiles and landing cases.

Based on the requirements and use case cases, a first Modelica library has been developed, comprising a large amount of aircraft and environment model components. A fully functional aircraft model has been developed in parallel, based on components from the library and model data for an A320-sized aircraft. Most of this data was computed using internally available numerical methods and tools. For example, the Vortex Lattice Method (VLM) in combination with manual tuning to meet stall speeds were used to develop a full aerodynamic model that covers all aircraft flight configurations. Also a weight and balance, landing gear, engine and actuator systems model were implemented.

The landing gear model includes variable friction coefficients to represent various types of runway conditions. A redundant actuator model has been developed, which can be deployed in active/active or active/passive operation mode. The actuator model allows for simulating aileron actuator force fight in various modes, like gain deviation, offsets, time delays, etc. The modelled force fight results in deformation of flexible rudder. Also, actuator failure cases are considered, such as runaway until the maximum or minimum deflection or an intermediate position and immediate deadlock.

All components are replaceable. In this way, the aircraft model library and integrated model allows MISSION components to be implemented and tested in a “virtual aircraft”

In order to allow the aircraft model to virtually fly prescribed missions, a fully functional autoflight system and pilot models have been integrated. This system is a DLR internal development, but has been adapted for the use cases in OPeRATOR. The control algorithms allow for the simulation of full flights, including taxi, take-off, climb, cruise, descent, approach, landing and flare /cross wind alignment and braking.

So far, tests of climb, cruise, descent and automatic landing scenarios have been tested. Also a rejected take-off scenario as been implemented.

The first, but already very comprehensive model library and aircraft example model have been delivered to the MISSION lead partner.
The model library in its current status already allows for simulation of aircraft missions with detailed aircraft flight dynamics and systems models. The use of the Modelica language hereby allows for the use of fully integrated, multi-physical and multi-disciplinarey aircraft models, both for over-all design optimization, as well as for detailed analyses of individual systems components. This is the first time that such an extent of model integration can be used from early aircraft design stages.

Work will continue to refine model components, extend the library, validate models and model components, and integrate the library withing the MISSION aircraft design framework.