# Design, Manufacture and Wind Tunnel Test of a Modular FishBAC Wing with Novel 3D Printed Skins
## 8 Conclusions  
This paper presents the design, manufacture and testing (structural and wind tunnel) of a novel composite Fish Bone Active Camber (FishBAC)=morphing device with 3D-printed skins. A comprehensive conceptual design and analysis for structural and actuation sizing were conducted, followed by a comprehensive set of structural and material tests that validated the robustness of the design. Finally, a wind tunnel test was conducted to study the aerodynamic behaviour of this novel composite FishBAC device. Aerodynamic coefficients, as well as displacements and actuation power, were recorded in a quasi-2D wind tunnel test. A summary of the most relevant findings follows:  
1. The two-phase 3D-printed skin/stringer panels developed for this new generation of FishBAC design were successful. The ultimate failure strain of these skins is around \(\approx\)15\(\times\) higher than the strains these skins would observe during operation. Additionally, due to the material used and structure of the printed sheets, cracks propagate slowly, and they require significant additional loading to cause failure. Therefore, due to these excellent properties and their ease of manufacture, the two-phase 3D-printed skin/stringer panels are a promising solution for the FishBAC's skin.  
Figure 24: Actuation power draw as a function of actuation input angle, with varying pitch angle.  
2. The benchtop proof load and static actuation tests demonstrated the robustness of both the morphing device and the actuation mechanism.
3. The static displacements that this novel FishBAC wind tunnel wing model can achieve (i.e., \(z/c\approx 0.05\)) are on target with the camber deflections required for minimising power requirements in an active rotor blade morphing system, according to previous research.
4. The new design and manufacturing techniques implemented in this FishBAC wing lead to a feasible morphing device capable of achieving significant changes in lift coefficient (\(\Delta C_{L}\approx 0.55\)) with varying camber distribution. These design improvements are a significant achievement in terms of developing the FishBAC towards real-life applications.
5. No significant decrease in FishBAC displacements or increase in power requirements were observed in the presence of aerodynamic loads, at a freestream velocity of \(30\,\mathrm{m}\,\mathrm{s}^{-1}\), when compared to the static (no freestream) case.  
Conceptualization, A.E.R., S.F., R.M.H. and B.K.S.W.; methodology, A.E.R., S.F., R.M.H. and B.K.S.W.; formal analysis, A.E.R., S.F. and R.M.H.; resources, B.K.S.W.; data curation, A.E.R.; writing--original draft preparation, A.E.R., S.F. and R.M.H.; writing--review and editing, A.E.R., R.M.H. and B.K.S.W.; supervision, B.K.S.W.; project administration, B.K.S.W.; funding acquisition, B.K.S.W. All authors have read and agreed to the published version of the manuscript.  
This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 723491 as part of SABRE: Shape Adaptive Blades for Rotocrraft Efficiency.  
Not applicable.  
The authors declare that there is no conflict of interest.