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HIGH speed civil Tilt Rotor wInd tunnel Project

Periodic Reporting for period 1 - HIGHTRIP (HIGH speed civil Tilt Rotor wInd tunnel Project)

Reporting period: 2018-11-01 to 2020-04-30

HIGHTRIP (HIGH speed civil Tilt Rotor wInd tunnel Project) is a 3.495 M€ funded EU project to investigate the full scale high speed aerodynamic characteristics if the NGCTR (Next Generation Civil Tilt Rotor).
The time span of the 3-year project runs from November 1st 2018 till October 31st 2021.

The aerodynamic configuration of the Next Generation Civil Tilt Rotor (NGCTR) needs to be characterized at high speed by a dedicated wind tunnel test campaign.
Within the EU CleanSky 2 program new T- and V-tail empennages were designed and fabricated in the NEXTTRIP project, envisaging use for higher speeds. In order to fully exploit this research, HIGHTRIP will design a new model based on NEXTTRIP design philosophy and scale, re-using the new (instrumented) NEXTTRIP empennages. If complete re-use is not feasible, basic design, balances and remote controls will be re-used to limit the costs. Consequently, the exact model scale will result from sizing NEXTTRIP empennage to the NGCTR Technology Demonstrator geometry.

The partners will work together to design and manufacture new fuselage and new wing in the HIGHTRIP model, based on the NEXTTRIP tails and NICETRIP parts. NLR will coordinate the HIGHTRIP project and will perform wing design and manufacture. The Polish partners will focus on the design and manufacturing of the new fuselage. NLR will subcontract the non-powered high speed wind tunnel test to ONERA-S1MA, resulting in a data package (on model scale) corrected for wind tunnel effects.
To provide full scale Reynolds number data and perform aerodynamic characteristics analysis at high speeds and full scale conditions, extrapolation to full scale Reynolds numbers will be done by CFD.

The Next Generation Civil Tilt Rotor fast rotorcraft concept aims to deliver superior vehicle productivity and performance. The aerodynamic configuration definition of the novel tilt rotor NGCTR Technology Demonstrator needs to be validated further at high speeds.
By exploiting outcomes and facilities of NICETRIP (FP6) and NEXTTRIP (CleanSky 2) projects and providing a full scale high speed database of different empennage configurations, HIGHTRIP provides a vital contribution for the validation of an innovative tilt rotor concept, the configuration of which will go beyond current architectures of this type of aircraft
Work package 1: Management, dissemination and exploitation
After the kick-off WebEx (2018/11/06) a face-to-face kick-off meeting was held at Leonardo’s premises in Cascina Costa, Italy (2018/11/19-20). The project had a slow start due to a change of scope and late delivery of geometry and loads. After delivery of final information (2019/04/01) regular WebEx meetings were held to discuss design (see: WP2) and subcontract (WP4).

Work Package 2: Design of the unpowered model components
At the beginning of the project the scope of the original work was slightly changed.
Due to the change in scope and the late delivery of geometry and loads the real start of the project was delayed for some months. Ongoing actions and regular progress meetings resulted in a Critical Design Review in February 2020. Drawback is that the design still has to be discussed with ONERA, who could not participate in the meeting (see also WP1).

Work package 3: Manufacturing of the unpowered model components
ILOT has sent drafts of drawings for checks to P.W. Metrol and SZEL-TECH and their feedback is positive. Programming for the manufacturing is in progress. However, manufacturing activities have not started in Poland yet, pending on signing of the subcontract by ONERA (see WP1) and their feedback with respect to materials and design.
In spite of the delay, NLR decided to start manufacturing in order to minimize that delay. Drawings are being made and programming for manufacturing the model parts is in progress.

Work package 4: Wind tunnel tests of the unpowered model
An important contribution to the subcontract is the definition of the test matrix. Although this caused quite some discussions the test matrix has been finalized for the moment.
Due to the late finalization of the subcontract the original slot for the wind tunnel could not be realized. At the moment the wind tunnel entry is planned for March 2021

Work package 5: Wind tunnel data analysis and reporting
Work on the computational grid is in progress. NLR in-house tools are used to create a fully block-structured grid. Provisions are made to be able to exchange the tail geometry and movables. The tail geometries can be changed by swapping out a defined region of the grid. The blocks of surrounding the tail are connected to the main grid through non-matching grid interfaces. In this way, the main grid will remain identical, increasing confidence that the observed differences in forces and moments are due to the different tail geometry only. Movables such as the nacelle and flap will be included though the use of overset grids. The main grid around the fuselage, tails and nacelle is 80% complete. Work on the grids of the remaining movables has started.
Wind tunnel model
The model is unique in the sense that never a wind tunnel model has been equipped with so many balances; a main balance measuring the overall loads on the model, a wing balance measuring the loads on the wing-nacelle substructure, a nacelle balance to measure the nacelle loads, a tail balance to distinguish the loads on the two tails and further control-surface loads (2x aileron, 2x ruddervators, rudder and elevator).
In the trend to always aim for a more accurate load measurement and more accurate remotely controlled positioning of a control surface, new laboratory techniques will be put in where possible.

Reynolds number extrapolation and analysis for Tilt Rotors
A novel procedure will be applied here that will provide reliable corrections to the wind tunnel data. This is accomplished through extensive set of CFD calculations covering the complete range of Mach en Reynolds numbers as well as angle-of-attack and side-slip conditions. The range of Reynolds numbers will extend from wind tunnel to full scale conditions. This procedure will be followed for each of the two empennages. The result will be two very detailed sets of correction values to all force and moment coefficients, not just drag and lift, that take into account Reynolds number, Mach number, angle of attack and sideslip, and are specific for the tilt rotor concepts under consideration.

High Speed Machining (HSM)
HSM planned to be used for manufacturing of the fuselage, internal structure and interfaces, except reduction of manufacturing time can offer a wide range of advantages:
• Cutting force reduction;
• Small heat flow to workpiece, heat transferred into chips;
• Increased quality of manufactured parts;
• Reduction of finishing machining
Moreover, in addition to above features of HSM, it also allow to manufacture more complex shapes and thin walls, what can have impact on final weight of the part or surface fidelity.

By contributing to the optimization of the tail, to 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.