Boom’s supersonic jet, which was unveiled at the firm’s hangar in Centennial, Colorado, included 21 mostly engine-related 3D printed components. According to Benny Buller, CEO and Founder of VELO3D, the parts produced under the companies’ collaboration mark a “turning point’ in both the viability of supersonic travel, and the aerospace capabilities of 3D printed parts.
“Aviation hardware is especially difficult to manufacture with 3D metal printing, due to challenging aerodynamic designs that must be balanced with superior durability and high temperature requirements,” said Buller. “VELO3D’s technology allows the production of lightweight, complex designs for mission-critical applications in the toughest operating conditions.”
“Our partnership with Boom is truly an advancement for the metal additive manufacturing industry, and XB-1 supersonic aircraft is a game-changer for the aviation industry.”
Boom Supersonic’s XB-1 aircraft
Boom Supersonic was established in 2014 with the stated aim of making commercial supersonic air travel a realistic prospect again. The company’s XB-1 prototype aircraft is being developed as a proof-of-concept, demonstrating the potential of its Mach 2.2 (1,687mph) capable ‘Overture’ airliner, which it aims to commission by 2030.
The XB-1 represents the first independently-developed supersonic aircraft, and its custom composite structure comprises over 3,700 parts including landing gear, flight control actuators, and cooling systems. In order to tackle the colossal task of constructing its demonstrator aircraft, Boom has enlisted the help of two established 3D printer manufacturers.
Initially, Boom Supersonic worked with Stratasys, leveraging the firm’s F370 and Fortus 450mc 3D printers to develop over 200 tooling, prototype and test bench parts related to the XB-1. The companies followed this up with a longer-term agreement, which went beyond prototyping applications, and saw Stratasys’ F900 systems used to produce end-use parts for Boom’s supersonic craft.
Shortly after agreeing a new deal with Stratasys, Boom began to collaborate with VELO3D as well, to develop further end-use parts for its passenger jet. At the time, VELO3D claimed that its Sapphire systems, which are optimized to produce large diameter parts without supports, would enable the creation of enhanced aerospace components with little or no post-processing.
Following a string of successful qualification trials using VELO3D’s machines, the companies have gone on to produce a total of a variety of 3D printed parts, which are now fitted to Boom’s prototype XB-1.
VELO3D’s supersonic 3D printed components
Leveraging VELO3D’s Sapphire systems, Boom has been able to 3D print a total of 21 structural, engine and environmental control components for its prototype jet, with some featuring walls as thin as 0.02 inches. As many of the XB-1’s 3D printed parts are related to channeling air, including vanes, ducts and louvres, they needed to be narrow and complex, while also featuring high levels of tensile strength.
The geometric designs of the plane’s aerodynamic parts included tall, thin walls with high aspect ratios, which are difficult to manufacture with traditional processes such as welding and casting. VELO3D’s proprietary SupportFree printing process meanwhile, enables a high degree of design freedom and quality control.
As a result, Boom was able to to carry out its vision for the aircraft, without having to consider design any constraints such as supports. VELO3D’s Gene Miller, who worked closely with Boom’s design engineers, emphasized that the XB-1’s parts would not have been possible using more conventional production techniques.
“Boom designed all these parts specifically for their novel aircraft,” explained Miller. “The unique types of geometries they created for directing flow, with a focus on weight savings, couldn’t be done with sheet metal or casting or any other way. To reap the benefits of complex design and weight reduction together, the only option was to do it with metal AM.”
“Supersonic flight introduces a number of different phenomena and stresses you generally don’t see with conventional air travel.”
A number of Boom’s parts were also printed for use within the plane’s vital engine area, including manifolds for the Variable Bypass Valve (VBV) system, NACA ducts and two diverter flange parts. NACA ducts are frequently used in high-speed planes to capture exterior air, and channel it into the aircraft to cool the engine bays, making the parts critical to the craft’s safety during flight.
Ultimately, 3D printing the XB-1’s parts in titanium proved to be very difficult due to the material’s narrow processing window. Titanium is ultra-heat resistant, but if it’s cooled too rapidly, it becomes brittle and prone to cracking. What’s more, while traditional techniques avoid this issue, the craft’s ultra-thin designs would’ve been impossible to reproduce using machining or casting methods.
VELO3D eventually optimized its systems’ print parameters to reduce the amount of residual stress in the part, but Miller conceded that the project had stretched the firm’s current technologies to the absolute limit.
“This was a learning process on all sides,” concluded Miller. “Boom designed a part family that was new to us, really pushing the envelopes for weight reduction and thin-wall geometries, and we had a lot to learn as far as printing these components out of titanium and what to expect from the physics of printing them.”
3D printing ‘flight-critical’ engine components
A number of companies have developed flight-critical engine parts in recent years i.e. components that are crucial to a craft’s safety, and some have even gained certification for their end-use in commercial aircraft.
Honeywell Aerospace for instance, has received Federal Aviation Administration (FAA) certification for its 3D printed #4/5 bearing housing. The company’s aircraft part is a key structural component of the ATF3-6 turbofan engine found in the Dassault Falcon 20G maritime patrol plane.
Additive Flight Solutions (AFS) has worked with 3D printer manufacturer Stratasys and Singaporian aircraft specialist SIA Engineering Company (SIAEC), to gain AS9100D certification for its parts. The accreditation demonstrated that AFS’ components meet strict quality management guidelines governing the aviation, space and defense sectors.
Elsewhere, the Russian state-backed Advanced Research Foundation (FPI) and Federal State Unitary Enterprise (VIAM) have flight-tested their fully-3D printed MGTD-20 turbine engine. The motor was tested via a UAV, which reportedly managed to achieve speeds of up to 154 km/h.
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Featured image shows Boom Supersonic’s XB-1 prototype aircraft. Image via Boom Supersonic.