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Sunday, 9. August 2020

WP 6 Tools and Demonstration

Within WP 2 to WP 5 several advanced optical measurement techniques are improved for routine industrial application. The non-intrusive techniques are used to measure several structural and aerodynamic parameters including deformation, position detection, flow velocity, flow characterisation, shock position, surface pressure and vortex trajectories. WP 6 intends to develop application rules for these techniques and condense them in a readily available easy-to-use guide for optical in-flight measurements. Furthermore a toolbox for the preparation, execution and post-processing of the measurements will be created. Finally this application matrix and toolbox will be demonstrated on measurement tasks under industrial flight test conditions.

Task 6.1. Creation of an Application Matrix for the advanced in-flight measurement techniques

All advanced in-flight measurement techniques tested in WP 2 to WP 5 of AIM² are evaluated concerning the parameters they measure, the installation, their accuracy and their limitations. Application rules for the techniques will be found and a decision matrix will be formed. The research partners (CU, DLR, MPEI, NLR, and ONERA) will mainly deliver the basic information, while the industrial partners (A-F, AP, EVE, PAI, RUT) will give the boundary conditions for flight testing requirements.

Task 6.2. Development of useful tools for advanced in-flight measurement techniques

The majority of advanced optical measurement techniques need similar tools to prepare, execute and evaluate effective tests. In task 6.2 software tools are evaluated and as required are developed into a common format (e.g. Matlab scripts, DLLs, LabView). A list of useful software tools is to be created, i.e. a toolbox. The software toolbox that can be distributed in the consortium will be placed on the AIM² partner website for download. Useful tools in the toolbox will include:

  • calculation tools for optics, setup design, accuracy estimation
  • calibration toolboxes, filtering toolboxes, pattern creation software
  • data reduction software
  • conversion tools, data plotting software

Development of such a toolbox does allow users to optimise future measurement techniques in a standardised format across a range of applications.

Task 6.3. Research flight test on a Motor glider concerning wing deformation and verification of numerical calculations

With respect to the developments in WP 2, in particular task 2.1, an optical wing deformation measurement setup is designed for the RUT AOS-71 motor glider. Input from task 2.2, 2.3, 6.1 and 6.2 is used to optimise the setup. The final measurement system will be installed to the RUT AOS-71 and a flight test will be conducted by RUT. The results of the test is to be compared with numerical calculations on the motor glider structural model by RUT.

Task 6.4. Advanced Flight Testing Workshop

A dedicated flight testing workshop will be hold at the Aviation Training Centre of RUT. Over one or two weeks the AIM² measurement techniques will be outlined in detail to the participants of this workshop with a focus on industrial flight testing personnel. But also students of aviation and space technology will be invited. Given a range of applications, the participants will then be shown how a suitable measurement technique can be chosen. Finally one measurement task will be applied by the participants with the guidance of AIM² personnel using the application matrix and the toolboxes. In this case, hardware that has been flown on the RUT aircraft will be used to demonstrate this flight test. A special course book will be prepared for all participants.

Task 6.5. Combined image based flow and deformation measurements on a transport aircraft

The results of WP2 and WP5 are used together with the application matrix and the tools from WP6 to complete a test on an Airbus A320 transport aircraft for the demonstration of combined image based flow and deformation measurements.

Task 6.6 Landing gear deformation measurements in an industrial environment using optical measurement techniques

An attempt to install an antiskid system on the P180 aircraft several years ago resulted in the rupture of a number of landing gear components. The cause of this failure was connected to the landing gear geometry. A theoretical analysis has shown that the P180 main landing gear is subject to a situation known as “gear walk”. ’Gear walk’ occurs during the braked ground roll, when the main landing gear leg tends to deform causing a tilting of the wheel. This tilting creates an angle between the wheel plane and the aircraft direction. When this angle reaches a certain value the braking coefficient is reducing causing a reduction in the force and corresponding deformation. This interaction then results in a wheel vibration at its natural frequency.

Service experience has shown that it is almost impossible for the pilot to excite the vibration, but that in the majority of cases, ’gear walk’ events occurred during testing, with antiskid set to normal.

This AIM² task with Piaggio aims to evaluate the deformation entity during a series of real braking events, where as required, with the installation of the suspect antiskid braking. These deformation measurements will allow confirmation of the theoretical analysis and validation of the theoretical model. Upon model validation, solutions which use a reduced efficiency of the antiskid (a reduced maximum braking coefficient) will be studied. In this case, the deformation measurement with the reduced settings will allow analysis of the safety margin. With the knowledge gained in former measurement activities and within WP 2, DLR will help PAI to perform this deformation measurement task. Also the application matrix from task 6.1 and the toolbox from task 6.2 will be used to prepare, conduct and evaluate the test under an industrial environment. DLR does provide the optical measurement system and PAI does provide the P180 aircraft and perform the test.

AIM² Advanced In-Flight Measurement Techniques, c/o German Aerospace Center (DLR), Bunsenstrasse 10, 37075 Goettingen, Germany, Tel: +49 551 709 2252, Fax: +49 551 709 2830, Email: