NASA’s X-59 quiet supersonic aircraft begins taxi tests

It was able to coast, eventually, but that’s some very fancy accounting.

“French Transport Minister Daniel Hoeffel, saying France ''will not and cannot abandon Concorde,'' signed a new agreement with Air France this week. The French Government, which with Britain had spent more than $2 billion developing the world's first supersonic passenger aircraft, will pay 90 percent of the plane's estimated operating losses for the next three years, compared with 70 percent in the past.

Under the new pact, the French taxpayer will contribute $66 million this year to the cost of Air France's champagne-and-caviar service linking Paris with New York, Washington, Caracas and Rio de Janeiro. In 1982, when losses are expected to decline slightly, the subsidy will be about $64 million, and in 1983, $59 million.”

A sonic boom is what you get when a traditional solid, largely flat-ish airfoil pushes air smoothly through the transition to supersonic flight. Very ELI5, but during the transition the energy/noise being put into the air basically stops dissipating from the aircraft at the point of transition, and so all that noise clumps together into a shockwave.

The shape of the X-59 makes it such that the transition doesn't happen uniformly over the air surfaces of the plane at the same time. It does get a little noisier around the transition, but it not a shockwave at all.

The ones at air shows felt more specious than the commercial ones. Or at least that’s how it was from my admittedly very limited first hand experience.

I was fortunate to fly an Air France Concorde between JFK and CDG and, while the seats were leather (which was not the case in economy at the time), they were no larger than economy seats.

The windows were tiny and the cabin itself was also quite small. It definitely felt cramped.

But yes that's what I meant, with a private plane you pay for the plane not per seat. I guess chartering a netjet would be cheaper than say 8 first-class seats.

NASA likes parachutes because they've always used parachutes. SpaceX likes retropulsive landings because Mars is their goal, and Mars' atmosphere isn't dense enough for parachutes. It's also safer for the crew in nominal operation and enables a much higher degree of rapid reuse, relative to NASA's traditional operation of taking a salt water bath in the ocean.

So they could go through the [very reasonable] extensive costs and testing involved in proving the safety of the retropulsive landings, or just go old school, strap a few parachutes on and work on getting crew to the ISS (which was the goal at the time). They chose the latter and with the plan of getting back to retropulsive landings later, which they also did. Parachutes remain the main landing mechanism for the Crew Dragon, but it now also has retropulsive landing capabilities to be used in case of a chute failure.

[1] - https://www.nasaspaceflight.com/2024/10/dragon-propulsive-la...

It wasn't because of safety, but because it would have needed tests, development and certification (for a new type of landing) while already having an established method (splashing into the sea).