Founded in 2014, Boom Supersonic is developing the Overture-type supersonic aircraft, a Mach 2.2 commercial airliner that can accommodate 55 to 75 passengers. For safety reasons, in recent years the company has been building a one-third scale demonstrator of the Overture-type supersonic aircraft, the XB-1 Supersonic Demonstrator. Key technologies for the mainstream supersonic flight will be demonstrated on the XB-1 Supersonic Demonstrator, primarily including advanced carbon fiber composites, as well as aerodynamic and propulsion design and analysis. Among other things, the XB-1 has carbon fiber and titanium fuselage and is 71 feet long. Its bowed (modified delta) wings enable safe operation during takeoff and landing, as well as at supersonic speeds.
A supersonic aircraft is an aircraft capable of flying at speeds exceeding the speed of sound by about 1,200 kilometers per hour, which can greatly reduce the time of long-distance travel and improve the efficiency of air transport. However, supersonic aircraft have not been widely used commercially due to the loud sonic booms they generate during flight, which cause noise pollution to the environment and humans, as well as their high operating costs and fuel consumption. At present, the only supersonic airliner that has ever been commercially operated is the Concorde, which was jointly developed by Britain and France, but this model of airliner also ceased operation in 2003.
Today, with the progress of science and technology and market demand, supersonic aircraft once again attracted people’s attention, NASA and Lockheed Martin’s co-development of the X-59HT aircraft is a time-sensitive supersonic aircraft, the goal is to verify a technology that can reduce the acoustic boom noise for the future development of the rules and standards for supersonic flights, to provide data support.
The XB-1, developed by Bohm, is a prototype supersonic airliner for the commercial market, designed to be capable of traveling at 2,700 kilometers per hour, about 2.2 times the speed of sound, reducing the New York to London flight to 3.5 hours.
XB-1 Supersonic Demonstration Aircraft Update
According to Boom Supersonic‘s official website, as the year 2023 comes to a close, the company’s XB-1 supersonic demonstrator has completed several pre-flight milestones and is preparing for high-speed taxi tests, which will take place once the aircraft is fully cleared to fly, currently scheduled for early 2024. Over the past 2023, the XB-1 has received its FAA airworthiness certificate, completed an extensive Flight Readiness Review (FRR), and successfully executed a series of comprehensive ground and taxi tests.
The latest phase of recent testing has targeted three systems for improvement: upgrading the XB-1’s landing gear (to improve reliability), optimizing the engine air intakes (to improve engine stall drag), and adjusting the XB-1’s dampers (to improve stability and control). These aircraft-specific optimizations have delayed the XB-1’s first flight until early 2024. These experiences also reflect the core purpose of the XB-1: each represents a technological advancement that paves the way for the smooth and successful delivery of the company’s Overture supersonic airliner.
To date, the XB-1 has undergone extensive ground testing, including taxi tests up to 108 mph, ground vibration tests, fuel system tests, engine operability tests, chute tests, and multiple engine tests, including full-scale testing of the XB-1’s three J85 engines.
Carbon Fiber Composites in Supersonic Airliners
Specifically, carbon fiber composites are indispensable as key raw materials for the supersonic demonstrator XB-1, which has a fuselage, wings, vertical tail, horizontal tail, air intakes, ailerons, and rudder made of TC350-1 toughened epoxy prepreg from Toray Advanced Composites, a subsidiary of Japan’s Toray Corporation, and on the outside is also pre-coated with IM7 carbon fiber from US-based Hexcel, with only the engine nacelles and rear fuselage being metal.
First and foremost, carbon fiber composites play an important role in the XB-1’s fuselage structure. Because of its lightweight and high strength, carbon fiber is widely used in the external shell structure of aircraft. Compared to traditional metal materials, the use of carbon fiber can significantly reduce the overall weight of the aircraft, thereby reducing fuel consumption and emissions. This means that the XB-1 can fly at higher speeds while reducing its environmental impact.
Secondly, carbon fiber composites are also used in key areas of the XB-1 such as the wings and vertical tail. Because these areas are critical to the aircraft’s handling and stability, they need to have excellent strength and stiffness. Carbon fiber composites meet these requirements and offer better fatigue life and durability than conventional metal materials. Through the use of carbon fiber materials, the XB-1 can better cope with the challenges of wind pressure and aerodynamic forces during high-speed flight, providing a more stable and safer flight experience.
In addition to this, carbon fiber composites are also used in the design of some of the XB-1’s interiors. Due to the unique appearance, texture, and feel of carbon fiber material, it can be used in the interior design of the aircraft to create a sense of modernity and technology for passengers. This not only enhances the passenger comfort experience but also reflects the XB-1’s sophistication and innovation as a supersonic passenger aircraft.
Other Advanced Materials
An amount of titanium is also used in the XB-1. Titanium is extremely strong and is also compatible with carbon fiber composites, and the two have similar thermal properties, and closer expansion rates, making it an ideal pairing for supersonic aircraft construction.
The XB-1’s main landing gear bulkhead is made from a 4-inch-thick, 66-pound plate of titanium. It is one of the highest specific strength materials in the XB-1, and the bulkhead will carry most of the load at landing speed. When the XB-1 lands, the bulkhead will absorb up to 112,000 pounds of force from each landing gear. Due to the strength requirements of this section, much of the rear fuselage is also made of titanium.
While titanium is highly desirable in these specific situations, it is not feasible to build an entire aircraft out of this metal. It is difficult to source and very expensive, currently averaging $40 per pound compared to about $1 per pound for aluminum (both prices vary depending on market conditions and how the metal is purchased). Titanium is also difficult to manufacture. However, titanium-skinned aircraft do exist: the most famous of these is the Lockheed SR-71 Blackbird. This aircraft is part of a family of titanium-skinned spy planes, and during its development, specialized titanium tools had to be made, as ordinary metal tools would break the more brittle titanium. Coincidentally, the SR-71 includes some of the first carbon fiber composites used in aircraft construction.
Also used in the XB-1 is thermoplastic polyetherimide 9085, a thermoplastic that is not only 3D printable; it’s strong, lightweight, and flame retardant. In the XB-1, most of the three-stage brackets, clamping blocks, gaskets, tubing, and fuel shutoffs are manufactured inside Boom using 3D-printed Ultem 9085. Because 3D printed Ultem 9085 allows for rapid design iterations, it saves time and money. Before the advent of 3D printing, complex aircraft parts were milled from a solid piece of material, often with expensive, painstaking, and time-consuming effort.
While the XB-1 uses many new materials, it also includes tried and tested materials such as aluminum, stainless steel, rubber, brass, bronze, acrylic, and copper. Each is ideally suited to the specific purpose of each part and provides the strength, heat resistance, durability, weight, workability, and performance required for supersonic flight. These materials will provide enough material for the XB-1 when Boom is ready for launch and first flight.