Comment by slivym | Hacker News Reader

Comment by slivym | Hacker News Reader

I'd really like to see proper numbers on the fuel economy of these proposed solutions. Because whilst it's nice to throw your hands in the air and say 'Ah well it'll be like first class' - there are many problems with that.

Firstly, all the big commercial investment has gone into sub-sonic planes, so they've gotten much cheaper. So to just have the same cost-ratio as concorde between supersonic vs. Standard flight is a big ask today. Secondly, Concorde wasn't just expensive -it was uneconomical because they couldn't fill the plane at those prices. Concorde was built in an era before deregulation - flights are far more cost competitive today. Thirdly, removing the sonic boom seems to imply inefficient shapes for the aircraft in terms of fitting numbers of passengers in. So even if the engines were far more efficient, you still have the fuel efficiency per passenger to worry about. For example Boom Supersonic are planning a 55 passenger plane. That is laughable as a commercial proposition.

I'm certain that companies working on this have concrete expectations of the cost o f a flight per person and the expected demand, I would just love to know what those are.

Current aircraft are significantly slower vs 50 years ago due to fuel economy issues. At 30,000 feet airlines could fly just under 678 mph, but they actually ~575 mph. This pushes up the benefit of supersonic flight.

On top of that the top 0.1% is both larger and more wealthy making filling ~50 seats a flight at 30,000+$ a pop easier than you might think. Drop that into $5,000 territory and some people would this every week.

IMO it's actually business jets that are the best market. They fly fewer trips making fuel less of an issue.

Also, above a certain level of affluence, a person's time, is valued over money. Taking a private jet might be a good deal for anyone making the big bucks.

”Boom Supersonic are planning a 55 passenger plane. That is laughable as a commercial proposition.”

Do you feel that is too big, or too small? The market for supersonic travel is likely to align with the very high-end, private jet market. Those who want to get somewhere fast and don’t care what it costs.

It may be easier to overcome noise issues with a smaller design, too.

My experience with private aviation suggests that getting somewhere exactly when they want, flying into airports closer to their destination, stepping directly out of/into ground transportation and, to a lesser extent, having privacy en route are significant drivers for the private aviation crowd.

Cessna is killing the X, the fastest civilian airplane, in favor of slower airplanes. I'm not convinced that supersonic transport to/from major airports is going to threaten business/private jet aviation.

Assuming noise regulations can be met, is there any reason why a small supersonic aircraft couldn't operate private flights into those same airports? Or do supersonic airframes need longer runways for higher-speed take offs and landings?

It should have sufficient power reserves to work with a normal 747-style runway. And starting/landing is done subsonically anyway, as one does not want wheels outside at those speeds.

I see no reason this should not work.

All of today's supersonic aircraft need runways longer than a mile. It is my belief that these projected supersonic aircraft will still likely need a mile or more.

There are 19K runways in the US, the vast majority of which have a longest runway under 4000'.

It's too small for a commercial flight. A commercial flight needs to carry enough people to be cheaper than a private flight. With the exception of exceptionally long flights, private flights can match the total travel time of a commercial flight on a much faster plane because they can can match the passengers' preferred start and end locations and the passengers' preferred schedule much more closely than a commercial flight can.

Supersonic flights will be very much a premium fare option, due to the significant increase in energy use and fuel required for supersonic flight.

Make a supersonic aircraft too big and you risk not being able to find enough passengers willing to pay fares that make it viable - which is one of the issues that killed Concorde.

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