S U P E R SO N I C Without extreme acoustic suppression, Boom markets subsonic speed as 20% faster overland, claiming a lower noise footprint than Concorde through modern design. Emphasising transoceanic routes (LA-Tokyo, currently 11-12 hours) supersonic flight would have great Pacific impact. With the NY-LA great circle at 2,500nm, the US domestic interest is also in halving the coast-coast commute. Air travel and wealth have evolved significantly since Concorde. From 2004-19 the number of global, scheduled passengers increased from two billion to 4.5 billion, cited as down to the growth of the global middle-class, particularly in China, and airport infrastructure spend. The number of millionaires has also risen sharply: a four-fold increase, to 62.4 million, between 2000 and 2023, 39% residing in the US. Concordes enduring value as a time machine for high-net-worth individuals makes private jets appealing; hence the Boston-based Spike Mach 1.6 bizjet concept. Latest-generation bizjets (G-650, Falcon 8X) permit M0.925, with M0.94 anticipated for the Global 8000. Boom has revealed an interest in VIP and military variants, including Air Force One. This raises the social acceptability of the minority producing most emissions and supersonic travels relevance to the masses. Supersonic rebirth complicates the industry goal of net-zero emissions by 2050: supersonic passengers burning more than twice the fuel of subsonic, premium-class ones. SAF is no panacea, its tailpipe emissions the same as kerosene, the offset coming from feedstock crops sequestering CO2 as they grew. Its effect needs to be assessed, not assumed. At supersonic cruise altitudes (FL500+), nitrogen oxides (NOx) are injected where they cause most ozone depletion, prevailing longer than at conventional altitudes. The drier air would at least avoid the damaging effect of persistent contrails. The balance between these factors is under study; conflict exists between re-enabling supersonic flight, itself remarkable, and its consequences, better understood today. Responders to supersonic naysayers would observe similar things were said of the technical hurdles of supercruise, thermal expansion and digital engine Supersonic rebirth complicates the industry goal of net-zero emissions by 2050 inlet control in the 1960s. The economic, social and environmental challenges were less easily engineered. Airlines have typically favoured economies of efficiency over speed: the 747s key was its democratisation for the masses; even Boeings 2001 Sonic Cruiser repurposed into the 787. Regardless of NASAs findings and the viability of Booms design and markets, the reawakening ambition is compelling, reinforcing the historic view of a nation against supersonic because it lacked its Booms Chief Test Pilot is former US Naval aviator Bill Doc Shoemaker own product. In 1960s Europe, it was not acknowledged loudly enough how significant it was that the capitals of its supersonic manufacturing nations had direct access to the Atlantic. Ultimately, can new understanding and technology help our upwardly mobile society learn to stop worrying and love the boom? The XB-1 against the backdrop of the Mojave. Note very low elevator positioning 30 THE LOG Sum 24 pp26-31 Supersonic.indd 30 13/06/2024 12:43