Powerful engines. Strong metals. Sturdy landing gear.
When we think of aircraft parts, we imagine virtually indestructible materials and assemblies. 3D-printed parts don’t come to mind. But advancements in both materials and 3D printers are accelerating changes that make 3D printing the perfect fit for prototyping, tooling and flight hardware — not to mention replacement parts, interiors and even lavatory fixtures.
3D printing is transforming how we design and manufacture aircraft.
For the team that built XB-1, Boom’s supersonic demonstrator, 3D printing proved invaluable during each phase of the build. More than 300 unique parts are installed on the aircraft. But 3D printing contributed more than parts manufacturing to XB-1.
Three 3D Printers, Three Needs
Early in XB-1’s build, the Boom team partnered with Stratasys to explore options for 3D printing, also known as additive manufacturing. The program looked to 3D printing to meet three different needs: functional prototyping, tooling support and on-demand manufacturing of flight hardware. Three printers met the needs of the build: the Stratasys F900, 450mc and F370.
A warhorse of a machine, the Stratasys F900 takes center stage in Boom’s hangar. The F900 prints several materials, including ULTEM 9085 and ULTEM 9085 CG. Both are flame-retardant, high-performance resin thermoplastics with high strength-to-weight ratios, excellent heat resistance and high impact strength. The team used 9085 to print drill blocks and 9085 CG for the hundreds of parts that are already installed on XB-1. The 9085 CG is delivered with certificates of conformance, which has better traceability and process control than the standard material, making it ideal for aircraft parts manufacturing.
The Stratasys Fortus 450mc also prints a wide variety of materials. The team designated it for printing drill blocks with FDM Nylon 12 CF, an incredibly strong material. FDM Nylon 12 CF is impregnated with carbon fiber, making it ideal for printing stiff drill blocks. During the build of XB-1’s titanium aft fuselage, the team used hundreds of drill blocks, printing them overnight. It not only sped up the build but also reduced downtime for the team.
The Stratasys F370 typically prints with ASA, an economical and lower strength material that’s perfect for rapid prototyping and test fitting components. The team printed prototypes with the F370 to burn down risk for any unexpected clashes (part interference or mismatched areas where parts connect or touch), as well as fitment to existing flight hardware. Test fitting with 3D-printed parts supported design improvements, so when the team eventually manufactured parts, each fit like a glove.
Functional Prototyping: Designing the perfect fit
During the first phase of XB-1’s build, one of the first priorities was making prototype components for flight control systems, including mechanisms and mechanical components. The goal with each prototype was to verify that the part fit and also that worked together with other parts. With prototypes, the team could check for clashes (mismatch of connecting parts) before investing valuable resources in manufacturing the part.
By printing multiple iterations within a few hours and fine-tuning designs, the team kept the build on-schedule. They also avoided the types of delays that happen when a part arrives from a manufacturer and doesn’t fit. And by keeping these functions in-house, the team kept downtime to a minimum.
All printers were put to work making prototypes ranging from a fuel manifold to engine mounts. The team 3D printed the outboard engine forward mount, for example, to check the fit against the left and right engines. Following several iterations, they successfully validated the design during a fit check.
Tooling: Achieving greater accuracy and reducing potential damage
During the course of XB-1’s build, the team harnessed the F900 and 450mc’s capabilities to print more than 550 drill blocks. The blocks supported the careful assembly of the titanium fuselage along with other printed jigs, including those for the cockpit bulkhead.
The team used metrology to drill holes with the blocks, which resulted in greater accuracy. And with greater accuracy, the team mitigated potential damage to the aircraft.
Without 3D printing, lead times for drill blocks would have been in the neighborhood of weeks, not to mention tens of thousands of dollars to fabricate out of aluminum. With in-house 3D printing, those same blocks took only a few days to print at a lower cost.
Metallics: Titanium 3D-printed parts that take the heat
Thanks to significant industry advancements, 3D printing with almost any material is now possible. Silver, photopolymers, stereolithography materials (epoxy resins) and even titanium can be applied to 3D printing.
Boom formed a partnership with VELO3D to produce metallic parts that would otherwise take weeks if not months to machine. In total, the company 3D printed 21 parts for XB-1, including some of XB-1’s most complicated titanium parts: manifolds for the variable bleed valve (VBV) system, which expels excess air from the engine compressor.
In the case of the VBV manifolds, using traditional manufacturing methods like machining, welding or casting would have been impractical. They were only able to achieve the desired part geometry using 3D printing.
Lightweight 3D-printed parts: A game-changer for aerospace engineers
Not only did 3D printing save time and resources during the build, it also reduced the weight of the aircraft — a game-changer for all aerospace engineers. Because aircraft weight is directly related to fuel consumption, the goal of aerospace engineering is to build an aircraft that’s lightweight while still meeting all safety requirements. Lighter aircraft burn less fuel, so any reduction in weight has an enormous impact.
3D-printed parts, depending on the choice of materials, can be substantially lighter than their traditional counterparts fabricated with steel and aluminum. On XB-1, which has more than 340 unique 3D-printed parts, the combined reduced weight made a substantial difference.
Now that the manufacturing team has handed XB-1 off to the ground and flight test team, they’re turning their attention to the design and build of Overture, Boom’s future supersonic airliner. And for Overture, the 3D printing possibilities are seemingly endless, with options to 3D print parts for cabin interiors, the flight deck and galley — in addition to prototyping, fueling and flight hardware. The advancements in 3D printing fueling these possibilities will open new avenues for reducing production costs, accelerating manufacturing timelines, and reducing emissions by building lighter aircraft.