We read with cautious optimism the potential for future supersonic business travel. Spike Aerospace is advancing supersonic travel through the development of the Spike S-512, a supersonic business jet designed to cruise at Mach 1.6. This aircraft aims to significantly reduce flight times; for instance, journeys from New York to London could take approximately three to four hours instead of the typical six to seven.
But the most significant advancement is Spike Aerospace’s plan to mitigate the noise associated with supersonic booms via a technique called aerodynamic shaping. It was this ‘thunder-clap’ obstacle that finally led to the demise of Concorde more than twenty years ago (as well as soaring maintenance costs, an eye-watering fuel bill and a crash that killed 113 people).
Their proprietary Quiet Supersonic Flight (QSF) technology is engineered to produce a sonic signature of less than 75 PLdB (perceived loudness level) at ground level, resembling a soft clap or muted background noise. This innovation enables the S-512 to maintain supersonic speeds over land without causing disruptive noise, addressing a major challenge in supersonic travel.
That should pave the way for supersonic flights over land, said Vik Kachoria, Spike’s founder and chief executive.
“We call it a sonic thump,” he said. “It should be the sound of a car door closing about 100 feet away. A very quiet sonic boom. We’re positioning the fuselage, nose cone, wings and engines in such a way that there’s still a boom but you’re directing it upwards into the sky and minimising how it coalesces. What normally happens is the shock waves from different parts of the aircraft coalesce and that’s what magnifies the intensity.”
Spike is working on a plane the size of a business jet that will have between 18 and 28 seats, costing potential buyers around $125m (£97m), according to Mr Kachoria – which is the same price as a Boeing 737.
The jet, called the S-512 Diplomat, would cruise at 50,000 feet, where the air is thinner, and speed along at Mach 1.6 (1,220mph), twice the pace of a modern jumbo jet, though slower than Concorde’s Mach 2.
The design features a so-called cranked delta wing that minimises the shock wave while bringing the added bonus of reduced drag and improved efficiency, Mr Kachoria said. The result should be a perceived loudness level for people beneath the flight path of less than 75 decibels, regarded as the maximum acceptable for supersonic flights over land.
The boom doesn’t just happen once as a supersonic aircraft goes beyond the speed of sound, but is constant as air molecules are pushed aside with great force – creating a shock wave much like a ship produces a bow wave.
Anyone within 50 miles of the flight path will hear a boom, with the noise dissipating the further the listener is from the plane, though Mr Kachoria said people were not the only concern when contemplating supersonic flights over land.
“Concorde was criticised for shaking buildings and breaking windows.Then there are animals. The migratory patterns of birds are going to be affected by a loud sonic boom and really disrupted. And marine animals that use echolocation to figure out where they are and to find mates and prey,” said Kachoria.
Another notable innovation of the S-512 is its windowless cabin design. Instead of traditional windows, the aircraft employs external cameras that project real-time panoramic views onto high-definition interior displays. This approach not only enhances passenger experience but also improves structural integrity and reduces weight, contributing to overall efficiency.
