At this point, we all know that additive manufacturing is a go-to technology for prototyping. Still, that doesn’t mean we don’t like hearing about case studies, especially when they’re as interesting as this one. CRP Technology, an Italian developer of 3D printing materials, and Leonardo Helicopter Division 3D printed a model of the LEONARDO tiltrotor AW609 aircraft for wind tunnel testing. The impressive test model was 3D printed using CRP’s high-performance Windform composites and selective laser sintering (SLS).
CRP Technology was enlisted by Leonardo HD, a Rome-based helicopter manufacturer previously known as AgustaWestland, to help produce a small scale model (1:8.5) of the new LEONARDO HD tiltrotor AW609 for low speed wind tunnel testing. CRP was brought on to the project to help Leonardo meet the demands of a strict timeline without sacrificing quality, as well as to explore the use of its 3D printable high-performance composites for this particular application.
Traditionally, Leonardo relied on more conventional materials for its wind tunnel models, including wood and metal. More recently, however, the company started using a mixed solution of wood and composite fiber materials. Today, all the company’s models are produced using CAD-CAM approach which involves milling a structural aluminium and steel frame and 3D printing the external parts.
In this particular case study, CRP was tasked with 3D printing various external parts for the aircraft model, including the nose, cockpit, rear fuselage, nacelles, external fuel tanks and fairings. These parts were all printed from CRP’s Windform XT 2.0 composite material, which was selected for its good mechanical performance and dimensional characteristics.
The carbon fiber composite, which has been used extensively in the motorsport industry, also boasts high heat deflection (with an HDT of 173.40 °C), high stiffness, good tensile strength and other beneficial properties. After an in depth analysis, CRP says Windform XT 2.0 was the material to meet all of Leonardo’s goals and requirements.
When it came to printing the parts, some of the components were too large for the SLS 3D printer’s build envelope. This meant that CRP had to separate certain components into multiple parts—a process which required diligence to ensure that the printed parts would hold up well as against stress when re-assembled.
As CRP explains: “The CAD cut was done with a special technique in order to maximize the contact surface in the place where the structural adhesive would be applied, thus having, also for very big parts bit with relatively thin thickness, a great resistance to any kind of stress.”
The print process for the aircraft parts was reportedly completed in just over a day, with the whole production taking just four days. The printed parts were then carefully post processed and coated in a special liquid that made them waterproof and primed for painting.
When the 3D printed parts were completed, they were assembled with the metal frame by Metaltech S.r.l. and tested at Leonardo’s wind tunnel facility in Bresso.
Since then, Leonardo built a larger scale model of the aircraft (1:6) for high speed wind tunnel testing at NASA’s Ames Research Center. This model also integrated a number of external 3D printed components made using CRP’s Windform XT 2.0 carbon composite. These parts were printed by CRP USA, CRP’s partner in North Carolina. The newer aircraft model, with a wing span of nearly two meters, also integrated a number of improvements to its design.