Innovative weight and balance measurement system for Tiltrotor application

The aeronautical sector through Clean Sky 2 Work Programme aims at contributing to one of the key Societal Challenges' smart, green and integrated transport' defined in Horizon 2020, enabling cutting edge solutions to decrease the environmental impact of the sector and to achieve the ACARE goals, facilitating the first steps to the Flightpath 2050 targets that include 75% cut of CO2 and 90% of NOx consumptions as well as 65% noise reduction, also improving the mobility within the EU.
Clean Sky 2 affords the development of different technology demonstrators to advance towards the mentioned objectives. The Next Generation Civil Tiltrotor (NGCTR) is within the AIRFRAME ITD (Integrated Technology Demonstrator) devoted to the develop and validate technologies that affect the global vehicle level; but also, is within the Fast Rotorcraft IADP (Innovative Aircraft Demonstrator Platforms) aiming at new configurations bridging the gap between conventional helicopters and utility/commuter fixed wing aircraft: both in speed and range/productivity. Taking that into account, this project focuses on an external element that would be used to assess the performance of the aircraft and to provide relevant information about the modifications needed to achieve a better performance during use, thus leading to the improvement of the behaviour of the vehicle and to the fulfilment of the targets of ACARE Flightpath 2050.
The Fast Rotorcraft IADP focuses on the development of a Next Generation Tilt Rotor that must be measured to balance their performance as a helicopter and as a fixed wing aircraft. In this sense, the outcomes of the project should contribute to the development of advanced flight control systems based on the advanced information about the mass, position of the centre of gravity and the information to achieve a suitable balance, contributing to the optimization of the general vehicle configuration, the engine installation and flight trajectories.
The possibility to change the configuration of the NGCTR between helicopter and airplane modes involves a redistribution of the mass of the vehicle and a change of the movement direction, become critical the identification of the mass distribution to avoid problems during flight and to improve the efficiency of the propulsion systems.
The obtaining of the mass and balance information is currently done in ground using scales that provide information about the location of the centre of gravity (CoG) projected in the floor plane. This limit the control of the vehicle, as the third coordinate of the CoG is unknown, being even more important as the vehicle can change its configuration, the mass distribution, and the advance direction between airplane and helicopter modes. This information also provides information to advance in the integration of new designs with more affordable composite structures.
In order to solve this limitation, the current project focuses on the development of an improved technology to assess the weight and balance of the vehicle in ground. The WEIBAL project aims at developing a complete measurement system able to detect the 3D position of the Centre of Gravity (CoG) of the plane and its pose in different configurations on ground. This will be done through the development of four subsystems: the scales; an elevation platform for the front wheel; a system to measure the relative position of the scales, the wheels and aircraft; and the measurement of the load application point in the scales. This will be complemented with an analysis of uncertainties to control and minimize the measuring error, both in the mass and in the relative positions of the scales.
Keywords: Sensor, Weight, Balance, Force, Aircraft

The activity has not been fully completed due to some delays in the preparation of the location for the system in the topic manager’s facilities. So, the activity of the WP4 has not been completed as indicated in the DOA. On the other hand, additional resources have been used to develop the second version of the platforms and to perform preliminary tests with an helicopter, a trailer and a small aircraft.
Within the WP1, the work has covered all the tasks, defining the systems specifications and the preliminary design of the solutions.
Within WP2, the activity performed has covered the detailed design of the different subsystem and their integration in the whole solution. After the design, the manufacturing and assembly of the hardware has been performed, including the design of the pit for the elevator. The result of the activity within the WP2 is the demonstrator of the system that will be installed in Leonardo (Italy),once the location and the pit are built.
Within the WP3, the work has covered the development of the software algorithms to treat the signals from the sensors (load cells and photogrammetry), as well as the definition of the controller, its software architecture and the HMI (Human-Machine Interface). The result is the software running in the electric cabinet, being this connected to the different platforms and cameras to work in a synchronized way.
The activity in the WP4 has consisted in the development of experimental tests to assess the behaviour of the complete system. The tests have been performed in Leonardo using a helicopter, in Tekniker using a trailer and in Bilbao Airport using a small aircraft.
In the WP5, the planned activities for communication have been performed, while the activities for dissemination has been partially performed, including the attendance to fairs and the presentation of scientific papers.
And within the WP6, the normal coordination activity with the partners and the topic manager have been performed, as well as the protection of the results with a patent application covering the WEIBAL measurement system.
Summarizing, the activities of the project have been performed with small deviations, including the fulfilment of the main milestones and all the deliverables of the project that have been submitted through the participant portal.
The main results can be summarized as:
• Development of the hardware and software of the WEIBAL system
• Validation of the system using a helicopter, a trailer and a small aircraft.
• Modelling of the WEIBAL system and the measurement process for the evaluation of the measurement uncertainty
• Two designs of the footboards for the weight measurement and the estimation of the load application point

The main advances beyond the state of the art are related to the following aspects:
• Development of the procedure and software for the 3D measurement of the centre of gravity of an aircraft (This has been patented).
• Development of the hardware required for the obtaining of the information needed for the 3D measurement of the centre of gravity of an aircraft.
• Fill and send the patent application covering the WEIBAL procedure.

Periodic Reporting for period 2 - WEIBAL (Innovative weight and balance measurement system for Tiltrotor application)

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