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NEXT generation civil Tilt Rotor Interactional aerodynamic tail oPtimisation

Periodic Reporting for period 1 - NEXTTRIP (NEXT generation civil Tilt Rotor Interactional aerodynamic tail oPtimisation)

Reporting period: 2018-03-01 to 2019-05-31

The aerodynamic configuration definition of the NGCTR needs to be confirmed by a large scale powered wind tunnel experiment, with the aim to verify and confirm the key choices of the configuration and to provide guidelines and proposals for potential additional improvement to be implemented. Within the EU 6th framework programme NICETRIP a 1/5th scale full-span, powered wind tunnel model has been designed and manufactured by NLR and tested in DNW-LLF and ONERA S1, with support of DLR. In order to fully exploit the FP6 research program, NEXTTRIP is based on re-using the existing NICETRIP powered model.

The partners will work together to modify the NICETRIP model, perform the wind tunnel test in DNW-LLF and define an optimal empennage configuration based on the wind tunnel test results and given boundaries. NLR will coordinate the NEXTTRIP project and will perform wind tunnel model design and manufacture, test preparations (including GVT), advanced flow visualization during wind tunnel test and wind tunnel data analysis. DNW will support test preparation and perform the wind tunnel test. DLR will support test preparation and perform data-acquisition and piloting. Multi-objective aerodynamic empennage optimization will be performed by Hit09 after wind tunnel data analysis. Fokker will, together with NLR, perform a verification of compliance with feasibility and industrial constraints during the empennage optimization process.

By providing a clear understanding of the efficiency (in terms of aircraft static stability) of different empennage configurations exposed to the rotor flow NEXTTRIP provides a vital contribution for the validation of an innovative tilt rotor concept. An optimized light weight and low drag empennage and consequently reduced emission and fuel burn will directly contribute to an efficient configuration capable to meet the ACARE Horizon 2020 goals.
Compared to the classical helicopter configurations, NGCTR will provide more speed, longer range, more productivity to fill the gap between conventional helicopters and other fixed-wing platforms. It will contribute to open a new segment of air transport and mobility, in line with increasing demand for flexible and smarter mobility solutions. Indeed, door to door travel will be significantly improved

To realize above, the main objectives of NEXTTRIP were defined and can be broken down into three sub-objectives:
O1 Modify the existing 1:5 scale NICETRIP model to accommodate two new empennage geometries in addition to the existing T-tail geometry.
O2 Complete a powered (and non-powered) wind-tunnel campaign for a relevant test matrix that is based on NICETRIP experience and which captures the flow phenomena in relevant flight conditions in reports (forces, moments, pressure).
O3 Based on the processed wind tunnel data, define and execute a strategy to propose enhancements for the geometries, supported by CFD analysis.
"Explanation of the work carried per WP

Work Package 1: Design and manufacturing of the modified NICETRIP powered components
This objective was achieved; two new tails, a V-tail and a T-tail, were designed and fabricated to be mounted on a new rear fuselage and tail cone. Additional to the original scope new rotor blades were designed and fabricated as well.

Work package 2: Wind tunnel test preparations of the modified NICETRIP powered model
All model components were manufactured according plan. Installation of the model on the DNW sting support in the DNW experimental hall started slightly later due to the delay in delivery of some additional components and the availability of calibrated airline bridges and wind tunnel driving equipment.
In spite of that, the functional checks of instrumentation, model controls, the load calibration checks and the ground vibration tests could be adapted in such a way that lost time was recovered, without jeopardising their outcome needed to perform the wind tunnel test.
The model was ready to enter the wind tunnel at the end of May 2019 (also the end of this first reporting period), exactly according the original planning of the project,
Deliverables provided were: “D2.1 Description of piloting & model control system”, ""D2.3 Measurement results during test preparation phase"".

Work package 3: Wind tunnel test with the modified full span NICETRIP powered model
In the time, covering the first reporting period, the test matrix was defined. Initiated by Leonardo, discussions with the consortium members helped to optimize the test matrix regarding time and thus, money.
Deliverables provided: “D3.1 Test Matrix”

Work package 5: Empennage optimization to enhance the stability behaviour of NGCTR
The aerodynamic optimization of V-tail concept is envisaged in WP5. Initial investigation and preparation of the work for this WP was initiated.

Work package 6: Management, dissemination and exploitation
As part of the project management, NLR issued deliverables “D6.1 Project Management Plan”, “D6.2 Proof of Signature of CA and IA”, “D6.3 Dissemination Action Plan” and “D6.4 Exploitation Plan”.
The new rotor blades of NEXTTRIP have been exposed at JEC from March 12 to 14. The link below presents the key figures of exhibitors, and professional visitors, which should give some idea.
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Publication paper """" (2nd reporting period): part of the work was conducted in the NEXXTTRIP programme.
"The development of the PIV seeding rake, based on Helium Filled Soap Bubbles (HFSB) seeding material, preceded much faster than originally planned. The original planning was that a small demonstrator seeding rake would be used in the NEXTTRIP test.
Part of these preparatory investigations were documented in:

Faleiros, D. E.; Tuinstra, M.; van Rooijen, B. D.; Scarano, F.; Sciacchitano, A.; ""Soap bubbles for large-scale PIV in industrial wind tunnels"". (
The paper is part of the ""Proceedings of the 13th International Symposium on Particle Image Velocimetry"" and presented at the ""International Symposium on Particle Image Velocimetry (13., 2019, München)""

Since the technique was demonstrated before that test, it was decided to scale up to a much bigger seeding rake with the dimensions, fit for industrial testing in a large facility. The 9 times bigger PIV seeding rake demanded more money than originally planned.

The new carbon fibre rotor blades (to be) used during wind tunnel testing have been exposed in the NLR stand at the Leading International Composites Show JEC 2019 (12-14 March) and at the PAS 2019 (Paris Air Show, 17-23 June).

By contributing to the optimization of the tail, which will be implemented on the Technology Demonstrator, the aerodynamics will be improved and effect the effectiveness of the vehicle.
With high maturity of technology integration aimed at completion of this rotorcraft program including flight demonstrations, the possibility to match ACARE goals (sustainable mobility) with actual
products to be subsequently developed will be substantiated