Dude, where's my supersonic jet?

Perceived Need and Use Cases

• Many commenters see little pressing need for civilian supersonic now that in‑flight Wi‑Fi, laptops, and decent cabins let you work or be entertained; time in the air isn’t “wasted” like in the 1970s.
• Others argue long-haul flights (12–20+ hours, or multi‑leg 27‑hour trips) are physically miserable and would gladly pay ~2× fare to halve flight time, especially when they can’t sleep on planes.
• Several people stress that travel time should be considered door‑to‑door; for many routes, halving cruise time only shaves a few hours from a 9–12 hour total. It’s transformative only when it changes “buckets” (e.g., 15h → 5h makes a same‑day intercontinental trip plausible).
• Consensus: the natural early market is elites and private/business jets, not mass-market economy.

Economics and Market Structure

• Strong skepticism that supersonic can be run “at today’s business-class prices” while carrying far fewer passengers and burning much more fuel.
• Moving high-yield business passengers to dedicated supersonic planes would strip profit from subsonic widebodies, likely raising economy fares.
• Several question claimed order books as mostly non-binding options/LOIs, and note that new airliners and engines typically need 5–10+ years and many billions to certify.
• Past Concorde economics are cited: high ticket prices, marginal profitability, limited range, and vulnerability to fuel prices.

Environmental, Noise, and Regulation

• Multiple commenters criticize the article for almost ignoring environmental impact; they argue aviation emissions should be reduced, not sped up.
• Sonic boom and general noise are seen as major externalities; overland supersonic bans are discussed, along with political motives and potential future relaxation.
• “Boomless cruise” and AI‑driven atmospheric routing are met with skepticism: seen as marketing that may not reliably prevent booms.

Technical Feasibility and Engineering Debates

• The article’s claim that Concorde burned 52% of its fuel taxiing is debunked with accident reports and historical papers; real numbers are ~1% taxi, ~20% to reach cruise. This error undermines trust in the piece.
• Long subthreads discuss taxi fuel use, electric or tow-based taxiing, and hybrid concepts; weight and complexity usually dominate any savings.
• LNG as jet fuel is debated: higher energy per kg and cryogenic cooling help at high Mach, but lower volumetric density and tank mass hurt subsonic jets. Methane leakage is an additional climate concern.
• Safety, sonic-boom mitigation, and especially engine design/certification are seen as huge obstacles; some think certain hypersonic programs are more technically grounded than the startups highlighted.

Alternatives and Experience Improvements

• Many argue the biggest time and pain reductions lie in ground-side changes: security “theater,” boarding processes, airport design, and VIP/tarmac transfers.
• High-speed rail is touted as the better answer for short-haul (1–3h) routes—where airport overhead dominates—though right-of-way and politics make new lines hard.
• Others say money would be better spent making existing flights less miserable (more space, better cabins) rather than faster.

Attitudes Toward Progress and Hype

• Some see a “cult of progress” chasing shiny, high-speed tech (supersonic, Hyperloop) while ignoring more prosaic but higher-ROI efficiency improvements.
• Others welcome supersonic as a premium niche that, if it works, may eventually drive down costs more broadly—as happened with aviation overall.
• The article itself is criticized as sloppy, possibly LLM‑like, overly credulous of startup claims, and light on industry realities.