In conversation with Kalea Texeira, who explained about NASA’s X-59 Quiet Supersonic Technology (QueSST) aircraft. In this interview she highlighted how it used materials and shaped its airframe to minimise sonic booms something earlier aircraft like the Concorde and F-18 never addressed. She also pointed out the importance of aluminium for aircraft construction.

To know more of her insights, read the full interview below:

Al Circle: What distinguishes the X-59's airframe and materials from earlier supersonic aircraft like Concorde or the F-18?

Kalea Texeira:  The X-59 Quiet Supersonic Technology (QueSST) aircraft represents a significant leap in supersonic aircraft design, particularly in its approach to airframe and material selection, distinguishing it markedly from predecessors like the Concorde and the F-18. While all three aircraft leverage robust materials to withstand the rigors of supersonic flight, the X-59's design is fundamentally driven by its primary mission: to mitigate the sonic boom.

Concorde, a marvel of 20th-century engineering, was primarily constructed from aluminium alloys, specifically Hiduminium ‒ RR58. This material choice was critical for its structural integrity and ability to endure the thermal stresses of sustained Mach 2 flight. The Concorde's aluminium nose, for instance, could reach temperatures of approximately 127 °C (261 °F) during cruise, causing the aircraft to lengthen by nearly a foot due to thermal expansion. While advanced for its time, the Concorde's design did not actively seek to suppress the sonic boom, which ultimately restricted its overland flight paths.

The F-18 Hornet, a versatile multirole combat jet, incorporates a blend of materials. Its airframe is predominantly aluminium, but it was a pioneer in extensively utilising composite materials, particularly carbon/epoxy composites, for structural elements like wings, doors, and control surfaces. Composites comprise a significant portion of its structural weight and external surface area, offering a superior strength-to-weight ratio an enhanced performance characteristics for combat manoeuvres. However, like the Concorde, the F-18's design is not optimised for sonic boom reduction.

In contrast, the X-59 is a purpose-built experimental aircraft, and its airframe and material selection are intrinsically linked to its low-boom design philosophy. While the X-59 is also constructed from conventional aviation-grade aluminium, its distinguishing features lie in its unique aerodynamic shaping and the strategic integration of components to achieve a quiet sonic boom. Its exceptionally long and slender fuselage, particularly the elongated nose cone, is designed to prevent shockwaves from coalescing into a loud boom. Instead, these shockwaves are spread out, resulting in a much quieter “thump”. This design priority means that while it uses familiar materials, their application and the overall structural geometry are revolutionary. The X-59 also incorporates components from other aircraft, such as parts from the F-18 and F-35, demonstrating a pragmatic approach to leveraging existing, proven technologies within its novel design.