The preliminary design of the local balance aimed at accurately measuring the aileron hinge moment was completed in November 2018 by TUDA. However, technical discussions between PRODIGE and the TM, focusing on design aspects related to balance features and balance-wing integration, led to a significant extension of the design review with the TM. In fact, at the end of the first period, different solutions involving wing-integral or aileron-integral balance arrangements were still under discussion.
An agreement has been found with the TM on the best architecture in terms of potential performance and safety, consisting in a wing-integral balance able to account for wing bending and torsion effects on the balance measurements.
The preliminary design of the model has been then completed by IBK and assessed in the Preliminary Design Review in September 2019.
The connection of the interchangeable ailerons to the aileron balance (fitting strategy), has been validated through laboratory leakage tests: at ambient conditions in DEHARDE in June 2019, and at cryogenic conditions at TUDA in July 2019.
Extensive analysis, and reiterated design loops needed to ensure proper accuracy of the aileron balance (that means flexibility of the sensing element) and, at the same time, suitable strength to ensure the structural safety, have been completed in the first months of 2020. The full WT model detail design has been frozen in April 2020 and then assessed and accepted by the TM in the CDR in May 2020.
All the WT model parts have been manufactured by DEHARDE. The wing has been delivered to TUDA in October 2020 to start with the aileron balance calibration.
The test rig to calibrate the aileron balance has been designed and implemented by TUDA. The balance calibration started in November 2020 at ambient conditions. The calibration in cryogenic conditions started in January 2021, with modified covers, and it has been completed at end of March 2021. The calibration at ambient conditions was repeated in April due to the aileron covers replacement, and it lasted till end of April 2021. Due to unexpected results in terms of repeatability of measurements during calibration, a further inspection after tests revealed a debonding of the SGs on the balance.
This issue, together with the very tight schedule before the delivery of the model to ETW, led to the agreement of re-instrumenting the aileron balance for WT tests and postponing the calibration after the productive test campaign in ETW.
WT model and test requirements have been extensively discussed with TM and ETW both during first and second periods: after many iterations, the test slot at ETW was reserved from the 21st of June to the 3rd of July 2021. The model was delivered to ETW during week #21 and the WT test campaign was performed successfully in the slot 21st June to 3rd July 2021 without any criticality.
The calibration was performed by TUDA according to the agreed schedule and calibration results were used by IBK to recover the aileron hinge moments in all the WT conditions. Results were discussed with ETW and TM on 20th September 2021.
