Using heavily filled composite stereolithography resins from DSM Somos, Italian rapid prototyping service bureau Provel is opening up new frontiers in wind tunnel test applications with the development of a scaled prototype of the new M-346 fighter trainer aircraft for Alenia Aermacchi.
The M-346 is the only new-generation advanced fighter trainer in the world. Including a variety of unconventional attributes, advanced technologies, and avionics, the M346 features superior performance over existing advanced trainers. Essential to the development process was the creation of an accurate, scaled prototype for effective wind tunnel testing.
Based on the inherent complexity of the prototype design, Provel chose to produce the model using the DSM Somos® composite stereolithography resin ProtoToolT 20L, rather than the popular powder sintering technique.
Belonging to the Somos family of ProtoCompositesT materials, ProtoToolT 20L is a ceramic-filled resin producing highly stiff and accurate parts. With a modulus of 10,000 MPa, a linear shrinkage of less than 0.025 mm, and a heat deflection temperature (HDT) of 279°C, ProtoToolT and the newly commercialized NanoToolT have become popular resin choices in wind tunnel test applications for industries including aerospace, automotive, and motorsports.
"Somos® ProtoCompositesT materials have the mechanical properties -- particularly the dimensional and structural stability -- that are essential for these kinds of aerodynamic tests," says Francesco Giorgio Buson, managing director of Provel.
The dimensions required for the scaled model of the M-346 were 1,000 x 1,000 x 200 mm. Because some parts were much larger than stereolithography equipment will permit, the model was constructed in several pieces and then assembled. The complex stages of creating the partition lines and reassembling the parts "were a delicate and crucial aspect of the project," helped by the accuracy of the Somos composite resin, as well as an adhesive that was specially adapted for the material to ensure an even and high-quality surface finish.
Perhaps the most important advantage provided by the ProtoCompositesT material during development of the M-346 model was the overall time and cost savings achieved.
"The ProtoTool prototype was ready for aerodynamic tests in less than half the time that would have been required using a traditional technique," says Buson. "The entire project could be completed in just over two weeks: one week for production of the models and another for the finish, assembly, and dimensional check."
As a result, the final cost analysis on producing the M-346 model with ProtoToolT demonstrated a cost savings of more than 30%. "Producing a model of this type using conventional technology would have taken several months for its design and development, costing several hundred thousand euros," says Buson.
As a result of the shorter implementation time, as well as the functional and aesthetic results produced by the Somos material, Alenia Aermacchi now considers ProtoToolT 20L stereolithography resin a standard for creating wind tunnel test parts for their aircraft designs.