The project consisted of the construction of a seamless, precision welded flat master mould manufactured to such a high quality to enable the embossing of painted riblets onto the outer surface of an aircraft. The riblets reduce significantly the drag characteristics under turbulent air flow. Each riblet is spaced 96µm apart and will achieve a sharp angular tip angle of 45 degrees. The depth of the riblet will be set at 48µm. A single riblet geometry seamless master mould (giant master). The consortium partners have joined together to create a combined level of unique expertise capable of manufacturing the precision quality essential for master mould manufacture.
The project will engineer and produce CAD-CAM designs for large format master mould or flat shim origination. These will be used to program a state of the art Excimer laser that will write a continuous negative riblet structure onto a polymer sheet. This large format polymer master will be silvered and placed into electroforming tanks to grow a nickel master shim. A series of sub masters and production shims will be grown from the metal master, to deliver metal master mould with dimensions of 1250 x 1250mm.
In addition a feasibility study to include sample welds will be undertaken to demonstrate how shims can be welded together to create nominally jointless and seamless shims.
The project is described and the deliverables attained are explained alongside images of the materials manufactured in the accompanying uploaded final report.
Project Context and Objectives:
The main objectives of the project was to design and produce nickel shims containing very precise surface riblets. The shim is a single piece capable of being folded into a cylinder and joined using a substantially seamlessly welding process. The shim manufacture and the welding process are state of the art and employed and developed as a consequence of this project. Full details including images of products produced may be found in the accompanying uploaded final report.
Before this project no group had been able to produce large (1250mm x 1250mm) continuous shims containing riblets that are consistently 51 microns high and spaced 96 microns apart. In addition it was imperative to join these shims seamlessly to create a cylinder capable of creating a series of sub-master shims that can be attached to an Applicator (produced by a separate project). A full description, including images of the products manufactured, may be found in the accompanying final report.
It has been independently verified that structured surfaces can exhibit beneficial air flow properties to large objects such as aircraft. The Riblet project is part of a much larger program to create a process of applying a nano-structured riblet surface to both new and existing aircraft bodies and wings. The objective is to reduce the drag caused by the flow of air past the aircraft and thereby reduce the fuel requirement of the aircraft. The deliverables of the Riblet project are to produce large scale structured shims capable of producing a series of equivalent sub-master shims that can be fitted to a dedicated applicator. The applicator design and production is a separate project from Riblet. Because the Riblet project is only one part of a much larger project we have disseminated the results to IFAM and Clean Sky's but have not disclosed them publicly to ensure that the other projects are not compromised.