[HN Gopher] Time to end the speed limit in US airspace?
       ___________________________________________________________________
        
       Time to end the speed limit in US airspace?
        
       Author : danboarder
       Score  : 89 points
       Date   : 2023-03-25 16:30 UTC (6 hours ago)
        
 (HTM) web link (www.elidourado.com)
 (TXT) w3m dump (www.elidourado.com)
        
       | AlphaCharlie wrote:
       | The faster the plane goes, the more fuel it consumes due to the
       | drag increase by the square of the speed. In a world where fossil
       | fuel is needed to fly airplanes and where oil is causing a
       | destruction of the world we inhabit, it's dangerous to suggest we
       | should make the flying industry polluting more than they already
       | are.
       | 
       | If anything we should look at the trade-off benefits of flying
       | with the least amount of fuel consumption per passenger and miles
       | flown. Flying faster than mach-1 to save time will be reserved to
       | a small elite. How does it benefit the masses?
        
         | raincole wrote:
         | Maybe it should be replaced with a fuel-per-mile limit?
        
           | sroussey wrote:
           | Maybe fuel per passenger?
        
         | panick21_ wrote:
         | > The faster the plane goes, the more fuel it consumes due to
         | the drag increase by the square of the speed.
         | 
         | ... at the same altitude.
        
           | mpweiher wrote:
           | IIRC, that's what made jet planes possible in the first
           | place. Jet turbines in general, and particularly the first
           | ones, were horribly inefficient compared to props. However,
           | they let you fly so much higher that it kind of canceled out.
           | 
           | The turbofan engines of today mitigate this inefficiency by,
           | in essence, strapping a big prop in front of the turbine,
           | except we call it a fan.
        
             | programmer_dude wrote:
             | Turboprop is also a thing BTW.
        
             | Brian_K_White wrote:
             | I think it's called a fan and not a prop, because it's a
             | fan and not a prop.
             | 
             | Props employ lift like a wing. Fans are screws.
             | 
             | It's really a spectrum where most props & fans actually
             | posess at least a little of both properties, and there are
             | some in the middle that had to simply be called propfans.
        
           | [deleted]
        
           | crazygringo wrote:
           | Oh interesting.
           | 
           | Looking it up, the Concorde flew at 60,000 ft, compared to
           | normal planes at 30,000 ft.
           | 
           | And atmospheric pressure at 60k ft is less than a quarter of
           | what it is at 30k.
           | 
           | Is it possible to fly twice the speed of a regular aircraft
           | but without using that much more fuel, by flying higher? Or
           | does the plane have to burn even more fuel to get up to that
           | altitude and maintain lift in a thinner atmosphere?
        
             | bombcar wrote:
             | There's a balance. And the Concorde had to have weird stuff
             | to get that high but yes - you can get better performance
             | higher to a point.
        
             | gallexme wrote:
             | Not twice as much I think, but it's definitly more efficent
             | to fly higher if it's in the efficent envelope of these
             | engines , just alone cause winds up there are way way
             | faster which can be very favorable, because of the Coriolis
             | Effect
        
             | klyrs wrote:
             | Take it just a little further: why not ballistic flight?
             | Sure, they call it the "vomit comet" for a reason but with
             | the right marketing and some investment in gravol, I feel
             | like the zero g portion of the flight should be a selling
             | point.
        
             | Retric wrote:
             | Which is offset by the need to climb through 30,000 ft on
             | the way to 60,000 ft.
             | 
             | It turns out that higher cruising altitude isn't nearly as
             | useful as atmospheric pressure might suggest. Aircraft end
             | up optimized for their cruising altitude, but there's a lot
             | of tradeoffs when targeting a higher altitude.
        
             | banana_giraffe wrote:
             | One of the bits of trivia about the Concorde: It nominally
             | flew at 60k feet, but a "cosmic radiation" sensor was
             | added, and if went above some limit, they would descend to
             | 47k feet or lower.
        
               | gorgoiler wrote:
               | I haven't ever thought of cosmic radiation in that way
               | before. It would be interesting to know more data on the
               | rate of bit flips when flying at altitude.
               | 
               | If I edit my photos on the flight home, am I more likely
               | to corrupt my files with bit flips?
        
               | NoZebra120vClip wrote:
               | I just imagined this as Nethack, where a pilot readout
               | suddenly says, "Oh wow! Everything looks so cosmic!" and
               | then everyone/everything in the cabin begins
               | hallucinating.
        
               | 57FkMytWjyFu wrote:
               | Not sure the quotes are necessary. That's exactly what it
               | was.
               | 
               | "In the days when the supersonic transport was in active
               | service, and cruising at between 60 and 68,000 feet, the
               | estimated radiation received by the crew was 50-130
               | mSv/yr. thus, obviously, as newer generations of aircraft
               | cruise ever higher, by the time we reach altitudes above
               | 60,000 feet, it is entirely possible that, especially
               | with crews flying trans-Atlantic or transpolar routes,
               | the acceptable maximum safe dose of radiation per year
               | will be exceeded. In addition, these numbers do not take
               | into account the possibility of pregnancy in female
               | crewmembers. "
               | 
               | See Van Allen Belts.
        
             | zamnos wrote:
             | Doesn't that also imply that it would be possible to fly a
             | modified plane at the regular speed of a regular aircraft
             | at that much higher altitude, and use way less fuel?
             | Airlines' main cost driver is fuel, so it seems like they'd
             | take advantage of that as much as possible.
        
               | t0mas88 wrote:
               | It's not that easy.
               | 
               | If you go higher, the speed of sound decreases so you
               | have to go slower to avoid going above the critical Mach
               | number for your aircraft. Normal airliners have to stay
               | quite a bit below Mach 1 to avoid any part of the airflow
               | going supersonic, since that would create big issues like
               | shock waves making the aircraft uncontrollable.
               | 
               | But due to the air being really thin, you also have to go
               | faster. Otherwise your wings will not generate enough
               | lift to keep flying.
               | 
               | At some point you cannot go faster and you cannot go
               | slower, that effect is called Coffin Corner and limits
               | how high a subsonic airliner could fly: https://en.wikipe
               | dia.org/wiki/Coffin_corner_(aerodynamics)
        
               | barelysapient wrote:
               | I think that would require a different plane design since
               | they'd have less lift at that altitude.
        
         | davidw wrote:
         | Seems like a good job for a carbon tax to change the economic
         | calculations involved. Perhaps for some, the speed would be
         | worth it, but they'd be paying for it.
        
           | hanniabu wrote:
           | The more credits they buy, the more expensive they should
           | become
        
             | mLuby wrote:
             | Yes, because the carbon-emitting companies are having to
             | buy those credits from carbon-reducing companies.
             | 
             | The more demand there is, the more incentive there is for
             | carbon-reducing companies to arise.
        
         | snapplebobapple wrote:
         | This is a terrible argument because it presumes there are no
         | uses of faster travel that are beneficial. The proper argument
         | is for a carbon tax that captures the externalities caused by
         | emitting carbon and then to let individuals decide if they want
         | to pay that or not for whatever activity they are partaking in.
         | 
         | Whether it benefits the masses or the elite is irrelevant, what
         | is relevant is that the use is worth more than the correctly
         | priced cost of carbon
        
           | aziaziazi wrote:
           | What is relevant is the inhabitability of the earth, not who
           | pays what.
        
           | thfuran wrote:
           | >Whether it benefits the masses or the elite is irrelevant
           | 
           | Why is that irrelevant? Must we permit everything that might
           | be of benefit to someone, even if it comes at the expense of
           | everyone else?
        
             | Nextgrid wrote:
             | > Must we permit everything that might be of benefit to
             | someone, even if it comes at the expense of everyone else?
             | 
             | If we can offset "the expense of everyone else" (in this
             | case via a carbon tax), why not?
        
               | thfuran wrote:
               | Assessing a tax doesn't actually clean the air. All it
               | does is ensure that only the rich have the right to fuck
               | everyone else over. If the government committed to
               | funding carbon capture at a rate of at least as much as
               | they would've in the counterfactual where there was
               | instead a ban plus the additional amount funded by the
               | carbon tax revenue, taxing the externality would probably
               | be adequate redress, but that isn't ever going to happen.
        
               | Nextgrid wrote:
               | > Assessing a tax doesn't actually clean the air
               | 
               | Unless you use that tax to pay someone to clean the air?
        
               | thfuran wrote:
               | You have to both put the entirety of the tax towards it
               | and ensure that the fact that you're funding it through
               | the tax doesn't decrease the amount of additional funding
               | you put towards it or else that decrease effectively
               | decreases the tax rate (at least as far as carbon capture
               | is concerned). The second part is harder than the first.
        
             | snapplebobapple wrote:
             | Because the problem with carbon is that the cost of
             | emitting it is not reflected in the market price of the
             | things emitting it. This is called an externality in
             | economics. You fix the externality by taxing the carbon
             | emission at a level that covers the externality. After that
             | you let the much more efficient market sort out what emits
             | and what doesn't because it does a far better job than than
             | any grouping of hacker news commenters expressing what ever
             | combination of the seven deadly sins you think makes them
             | hate the most productive people in society. Markets work
             | and envious, wrathful authoritarians don't. You just end up
             | with another episode of great moments in unintended
             | consequences going down that road.
        
               | thfuran wrote:
               | >Markets work and envious, wrathful authoritarians don't.
               | 
               | So EPA, FDA, etc regulations should be replaced with fees
               | for poisoning everyone rather than outright bans, because
               | to desire freedom from such concerns is to be a jealous
               | tyrant?
        
               | avereveard wrote:
               | How are fines from fda and epa different than fees?
        
               | jltsiren wrote:
               | If you want to tax something, you have to define it,
               | measure it, and report it. You need a system for
               | collecting the taxes, a system for enforcing the
               | collection, and a system for validating that the reported
               | numbers are correct. You will need more regulations and
               | more bureaucracy than if you had simply banned it.
               | 
               | Banning something is a solution that prevents some people
               | from doing what they want. Taxing something is a solution
               | that subjects a (potentially much) larger group of people
               | to a reporting and tax burden and random inspections. If
               | it's authoritarianism you are concerned about, you have
               | to contrast the sizes of these groups and the potential
               | harms from the banning and tax collection to determine
               | which solution is worse.
        
               | Dylan16807 wrote:
               | That taxation system already exists for jet fuel. Nothing
               | new needs to be added.
        
           | pydry wrote:
           | >The proper argument is for a carbon tax
           | 
           | The proper argument is to get a carbon tax _first_ before
           | unbanning anything like this.
           | 
           | And it's not on the political horizon so....
        
             | denton-scratch wrote:
             | Carbon taxes (as they exist now) are a con. You just buy
             | some carbon credits from some company that is supposedly
             | carbon-negative, because it plants forests somewhere so
             | obscure that nobody checks.
             | 
             | And anyway, forests are _not_ carbon-negative; all that
             | lives must die. They 're carbon-neutral.
        
               | ianburrell wrote:
               | Carbon tax != carbon credits. Carbon credits are part of
               | emission trading approach. Carbon tax doesn't need
               | credits cause uses money. Not being cheatable is one of
               | the advantages of carbon tax.
        
         | dan-robertson wrote:
         | This seems like a pretty bad reason to want speed limits,
         | because the thing you actually want to limit is fuel
         | inefficiency. I think rules should normally try to achieve
         | their goals through first-order effects rather than second
         | order effects.
         | 
         | I don't think wanting fuel efficiency is incompatible with
         | getting rid of the speed limit rule.
        
         | seventytwo wrote:
         | If we had a robust carbon pollution tax, then this wouldn't be
         | a problem. The emissions would be priced into the ticket, and
         | we could all (theoretically) fly easy.
         | 
         | The root of all this is really just that the pollution from
         | fossil fuels needs to be paid for.
        
         | verandaguy wrote:
         | I strongly agree with your point, but I think some extra
         | context is warranted.
         | 
         | As it stands, the economics of air travel force carriers to
         | optimise for reducing fuel consumption, since that's (by far)
         | the biggest fraction of a commercial aircraft's operating cost.
         | 
         | If supersonic transport makes a comeback, it'll be because the
         | economics will make sense, which (in my mind) will be either
         | because of:
         | 
         | - Somehow reduced fuel consumption, potentially through engines
         | that leverage the effects of the supersonic flight regime for
         | increased fuel efficiency (e.g. ramjets, through that likely
         | wouldn't be possible in low-supersonic flight)
         | 
         | -> As another commenter in this thread mentioned, drag
         | decreases with lower atmospheric pressure at higher altitudes,
         | so there are fuel efficiency gains to be made just by flying
         | higher, within the engines' design constraints.
         | 
         | - It'll fill the niche of richer-than-god people who use jets
         | to skip highway traffic.
         | 
         | There's likely more cases than just these, but these are just
         | the greatest hits as far as I can tell; and I say all of that
         | as someone who's not involved in the aviation industry.
         | 
         | For the record, I don't support this second niche existing, but
         | it does, and it can be an economic driver.
        
           | drewcoo wrote:
           | > If supersonic transport makes a comeback, it'll be because
           | the economics will make sense
           | 
           | And not because it kills the planet less.
           | 
           | [cue sad trombone]
        
             | [deleted]
        
             | Nextgrid wrote:
             | You can offset environmental impact by excise-style taxes
             | on the polluting activity that are used to subsidize
             | environmentally-friendly processes elsewhere that would've
             | otherwise used fossil fuels due to cost.
             | 
             | It's not _perfect_ (as fossil fuels are still being burned)
             | but it 's better than nothing and a much more realistic
             | solution than some extremist ideas such as stopping using
             | fossil fuels overnight and effectively shutting down the
             | economy as a result.
        
               | bobthepanda wrote:
               | IIRC, with aviation fuel it's kind of complicated due to
               | international treaties on taxation of fuel.
        
               | kelseyfrog wrote:
               | You could, but you could also maintain the status quo.
               | Not everything needs a market based solution.
        
               | Dylan16807 wrote:
               | You can tax enough to remove 150% of the pollution. I'd
               | call that much better than the status quo. And that's
               | before we talk about the usefulness of funneling rich
               | people money into technology research.
        
           | htag wrote:
           | > It'll fill the niche of richer-than-god people who use jets
           | to skip highway traffic.
           | 
           | To skip highway traffic a richer-than-god person would use a
           | helicopter. Private jets are used for further distances.
        
           | AlphaCharlie wrote:
           | That's a very eloquent way to put it, I agree to it all :)
        
           | oliwarner wrote:
           | Given the ecological cost, the economic balance has to be
           | thumbed; taxed to the hilt to fund restorative programmes.
           | 
           | Being absurdly rich shouldn't give you license to destroy the
           | planet.
        
           | CyanBird wrote:
           | The second niche as a rule of thumb pollutes-more-than-God
           | already(0)
           | 
           | I am skeptical that lifting barriers to them polluting more
           | would land any type of net benefit given that ultra-luxury
           | products such as said jets don't tend to land outsized
           | downstream advancements than let's say, funding basic
           | sciences such as what Boeing or Airbus are already doing
           | 
           | (0) https://www.oxfam.org/en/press-releases/billionaire-
           | emits-mi...
           | 
           | If it could be proved that things like faster private jets or
           | faster planes could benefit in a sizeable and proportionate
           | way to the general public, then yeah I would be in favor of
           | this too, but as it stands I don't find the available info
           | compelling, I'd rather them to pay more taxes
        
             | verandaguy wrote:
             | You're preaching to the choir; human progress isn't
             | proportional to the number of billionaires with fleets of
             | Gulfstreams (or rather, if it is, there's almost certainly
             | no causation there).
        
               | aaomidi wrote:
               | I'm constantly in pain about how much human ingenuity
               | takes the back seat just to keep the wheels turning in
               | lives. If we actually tried to meet most of the
               | requirements for people, creative thinking would
               | flourish.
        
               | seventytwo wrote:
               | 100%.
               | 
               | I like to bring up the question of how many startups and
               | how much innovation is stifled because people stay with
               | their jobs because of the healthcare.
        
               | jandrewrogers wrote:
               | Isn't Europe evidence of the answer to this question?
        
             | [deleted]
        
         | bendbro wrote:
         | > In a world
         | 
         | > world we inhabit
         | 
         | > dangerous to suggest
         | 
         | > benefit the masses
         | 
         | I hope "the masses" put you in a camp. You need to be
         | reeducated until you stop writing like this.
         | 
         | PS. The camp I'm referring to is administrated by a communist
         | government, so your liberal sensibilities prevent you from
         | downvoting this comment.
        
         | goodluckchuck wrote:
         | [flagged]
        
           | arcticbull wrote:
           | > Bold claims such as man made climate change require bold
           | evidence.
           | 
           | Boy is it a good thing we have it then.
        
             | goodluckchuck wrote:
             | Would you mind sharing it?
        
               | AlphaCharlie wrote:
               | I'm going to assume you are not trolling and hope this
               | will change your mind, but I am not sure what proof you
               | expect will convince you. It's worth asking yourself
               | before reading these what is the level of proof you
               | require to be convinced, and then see if these are
               | fulfilling your expectations.
               | 
               | - from CalTech: https://scienceexchange.caltech.edu/topic
               | s/sustainability/ev... - from NASA:
               | https://climate.nasa.gov/evidence/ - from Cornell: https:
               | //news.cornell.edu/stories/2021/10/more-999-studies-ag...
               | - from Columbia:
               | https://news.climate.columbia.edu/2017/04/04/how-we-know-
               | cli... - See statements from scientific organizations
               | across the world (in case you the leading schools of the
               | USA aren't convincing you): https://en.wikipedia.org/wiki
               | /Scientific_consensus_on_climat... - scientific journal:
               | https://phys.org/news/2017-11-man-made-climate-
               | proven.html - united nations: https://www.un.org/en/un-
               | chronicle/climate-change-disasters-...
               | 
               | I have not read this one in depth but maybe it will help
               | change your mind on some misconceptions:
               | https://skepticalscience.com/
               | 
               | I'm happy to link similar studies from across the world
               | if you speak other languages.
               | 
               | I know for every link I send you, you will find an equal
               | number of links from climate change deniers. Put please
               | put in perspective the number of people on one side of
               | this issue and the other: the overwhelming majority of
               | scientists agree.
               | 
               | And even if they are wrong, is it really that bad to try
               | to burn less oil and make the air less polluted and our
               | planet more hospitable?
        
         | tormeh wrote:
         | > The faster the plane goes, the more fuel it consumes due to
         | the drag increase by the square of the speed
         | 
         | This is not actually true. Drag is at max at around mach 1.
         | After that it goes down again. If you go fast enough you can be
         | very efficient.
        
           | avereveard wrote:
           | Drag goes back from the transonic peak but not below what was
           | at subsonic speed.
           | 
           | The gain comes from being able to fly in thinner air if the
           | plan be is designed to survive the the transonic regime and
           | supercuise, because mach speed becomes lower higher you fly
           | and the air thinner, so lift available to subsonic planes is
           | limited
        
         | TylerE wrote:
         | You can get around that by flying higher, where the air is
         | thinner. This is easier if you faster.
        
         | looping__lui wrote:
         | Funnily enough the SR71 at Mach 3.5 had a better mpg than a
         | Boeing 747 below Mach 1. It's kind of hard to compare apples to
         | apples here - but at supersonic speed, different engine
         | technology can be used with better fuel efficiency...
        
           | [deleted]
        
           | taeric wrote:
           | You also have to compare getting to that speed. And, of
           | course, the comparison is dead when done per passenger. Might
           | as well compare a missile in there, or a drone.
        
           | SkyMarshal wrote:
           | Probably also because it flew much higher with less air
           | density and drag.
        
           | AlphaCharlie wrote:
           | The SR71 was flying at a much higher altitude to achieve
           | lower drag and fits 2 pilots, 0 commercial passengers.
           | 
           | If you want to compare apples to apples, I suggest you refer
           | to the 2 metrics I mentioned: - gallons of fuel per miles
           | flown - fuel used per passenger
           | 
           | One without the other is a useless comparison as you pointed
           | out.
        
             | looping__lui wrote:
             | U miss the point entirely that supersonic planes work
             | differently from "traditional" subsonic planes. Just
             | assuming that "faster equals less fuel efficient" is not
             | really correct. Turbofan engines are kind of draggy and not
             | so fuel efficient close to Mach 1. Ramjets change your
             | equation... :-)
        
           | post-it wrote:
           | A Ferrari probably has better fuel efficiency than a bus,
           | yeah.
        
             | speed_spread wrote:
             | Are you optimizing for throughput or latency?
        
             | looping__lui wrote:
             | And I guess the brains behind a Ferrari enjoy their work
             | more than engineers designing said bus. And Ferraris will
             | attract more attention than a bus. Maybe some things are
             | just unnecessary. Conquering the useless and doing
             | unnecessary things is what keeps me sane and happy. But our
             | mileage on that topic might vary.
        
             | dsr_ wrote:
             | True. An average city bus gets 7 mpg; an 812 Superfast gets
             | 13mpg.
             | 
             | The bus wins when carrying 3 or more passengers besides the
             | driver. And in a city with dedicated bus lanes, the bus may
             | win for route speed, too.
        
             | Already__Taken wrote:
             | Doing what? sat at 70mph, yeh probably. stop/starting
             | chundling around town I guarantee not.
        
           | tormeh wrote:
           | Drag also works differently at supersonic speeds.
        
           | dragonwriter wrote:
           | > Funnily enough the SR71 at Mach 3.5 had a better mpg than a
           | Boeing 747 below Mach 1.
           | 
           | The SR-71 had a maximum takeoff weight of 140,000lbs.
           | 
           | The 747 has a maximum takeoff weight of 735,000-910,000 lbs,
           | depending on model.
           | 
           | That helps quite a bit for the former using less fuel per
           | mile.
        
             | thfuran wrote:
             | And a considerably higher percentage of the 747's weight is
             | passenger/cargo as well.
        
             | looping__lui wrote:
             | [flagged]
        
           | gleglegle wrote:
           | Per passenger?
        
             | [deleted]
        
             | Retric wrote:
             | No.
        
           | lfowles wrote:
           | It also only carried 2...
        
       | neilv wrote:
       | For the convenience of the wealthy?
        
       | omeysalvi wrote:
       | "Let's create a nuisance for everyone so that billionaires can
       | save 20% time in the air"
        
       | gamblor956 wrote:
       | No justification is given for ending the ban. Supersonic places
       | are expensive enough that supersonic flight will be the exclusive
       | domain of the wealthy for years.
       | 
       | I'm okay with not having to deal with the booms if it means the
       | wealthy are stuck flying the same speed as the rest of us.
        
         | chrisbrandow wrote:
         | The obvious retort is that many modern conveniences began as
         | expensive goods that we eventually figured out how to scale, or
         | make more cheaply. It's not as obvious that this counter-
         | argument is robust, given the known history that we have with
         | the Concord3. But if the economic is won't work out, they won't
         | work out.
         | 
         | But I'm increasingly leery of arguments that imply the best way
         | to achieve fairness is for everyone to have fewer nice things.
         | And I say that as someone who thinks we should be taxing the
         | wealthy at much higher rates than we do.
        
       | a0zU wrote:
       | Even disregarding the sonic boom, why would we even want mediocre
       | civil pilots to have access to aircraft thag are necessarily more
       | dangerous and more destructive in the event of a crash?
        
         | avidiax wrote:
         | Planes usually crash at takeoff and landing, hence supersonic
         | or not doesn't matter for that case.
         | 
         | Crashing at any other time, sure, there is potentially more
         | energy in a supersonic plane. I doubt that people on the ground
         | will know the difference between a plane crashing on them at
         | 600mph vs 1200mph.
        
       | pclmulqdq wrote:
       | What an amazing scientific experiment: "we flew a fighter jet
       | over a Texas city to purposely annoy people, and asked how
       | annoyed they were." Followed by: "only 17 people rated 'very
       | annoyed' so that's a win." No mention of the number of people who
       | put down any other annoyance level...
        
         | hughw wrote:
         | And annoyed people won't be able to like, move away from
         | Galveston and get away from it. It's going to be over the whole
         | country. Several times a day. I could see suicides rising.
        
         | dasil003 wrote:
         | I'm sure they also have an airtight statistical regression to
         | determine how annoyed people will be when it's happening 30
         | times a day!
        
           | fnordpiglet wrote:
           | In the NYC metro they have a capacity to launch 4200 flights
           | a day, and to my understanding it's about 3000 in actuality.
           | So! Enjoy!
        
       | rickydroll wrote:
       | While I don't worry about the impact of sonic booms on humans,
       | and were concerned about the impact on the rest of the natural
       | world.
       | 
       | Like low-level sonic booms, light pollution was never considered
       | to be a big issue but eventually crossed the threshold where it
       | now has significant negative impact on animals insects and
       | plants. My concern is that once little sonic booms become
       | commonplace and we start noticing the impact on the natural
       | world, there will be too much money in play to stop the damage.
       | 
       | https://www.nature.com/articles/d41586-018-00665-7
       | 
       | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2627884/
       | 
       | https://www.science.org/doi/10.1126/sciadv.abi8322
       | 
       | [edit] just remembered another low-level fact that people did not
       | think was important. Jet contrails significantly increase high-
       | level cloud cover which alters weather patterns and holds more
       | heat in the atmosphere. A simple change in flightpath by
       | modifying altitude by couple thousand feet can eliminate 80% or
       | more of cultural formation but the airlines won't do it because
       | of the small amount of additional money it would cost.
        
       | Scaevolus wrote:
       | Isn't the real killer of supersonic commercial flights the
       | inefficiency? You're using ~5x more fuel to have a flight that's
       | ~2x faster. I suppose you can recoup the fuel cost with expensive
       | tickets, but should we encourage even less efficient flights?
       | 
       | https://theicct.org/new-supersonic-transport-aircraft-fuel-b...
        
       | noja wrote:
       | "..there is something decadent about putting a complete halt to
       | the development of a key technology simply because a few
       | otherwise harmless sonic booms might annoy a vocal minority."
       | 
       | -> _benefit_ a minority?
        
       | Awelton wrote:
       | The low boom aircraft designs are something I haven't seen and
       | are quite interesting. I have been under a few "non low boom"
       | supersonics, and they rattle entire buildings and set off car
       | alarms.
        
       | danboarder wrote:
       | "Fifty years ago today, on March 23, 1973, Alexander P.
       | Butterfield, the Administrator of the Federal Aviation
       | Administration, issued a rule that remains one of the most
       | destructive acts of industrial vandalism in history. ... The rule
       | imposed a speed limit on US airspace. Not a noise standard, which
       | would make sense. A speed limit."
       | 
       | Imagine how quiet hypersonic planes would be now if the rule had
       | been a based on loudness instead of speed. I imagine getting from
       | LA to NY in an an hour in near-silence... That would be awesome!
        
       | fossuser wrote:
       | Makes sense to focus on the actual issue (noise) and not speed.
       | 
       | It'd be awesome to have supersonic commercial aircraft that were
       | also quiet. I'm excited about YC's Boom and their overature
       | plane, but it'd be so cool to able to fly coast to coast at
       | supersonic speeds.
       | 
       | Hopefully something like this can pass.
        
       | [deleted]
        
       | jcalvinowens wrote:
       | This is unbelievably ignorant... the author literally linerally
       | extrapolates the speed increases of early airliners to today and
       | says "we could have 2500mph airliners if the FAA didn't stop us".
       | 
       | If the author had done even cursory research, they would realize
       | there are many reasons we don't have supersonic passenger
       | aircraft, none of which have anything to do with government
       | regulation. Start by reading this:
       | https://en.m.wikipedia.org/wiki/Supersonic_transport
        
       | frompdx wrote:
       | _I'm struck by the fact that American economic growth went off
       | the rails in 1973, the same year the overland ban on supersonic
       | flight came into force._
       | 
       | This seems like a hasty conclusion to make. There are plenty of
       | things that correlate with the stagnation of economic growth. I'm
       | aware the author goes on to say almost the same thing after
       | making this statement, but it is clear the author is trying to
       | offer the ban on supersonic flight over soil to be the cause of
       | economic stagnation in America.
       | 
       |  _To borrow a term from Ross Douthat, there is something decadent
       | about putting a complete halt to the development of a key
       | technology simply because a few otherwise harmless sonic booms
       | might annoy a vocal minority._
       | 
       | I fail to see how there has been a complete halt on the
       | development of supersonic technology. A ban on supersonic flight
       | over US soil is not a ban on the development of the technology.
       | 
       |  _We need to get back to doing great things._
       | 
       | Who says we aren't?
       | 
       |  _If we want growth--if we want greatness--it's time to make
       | America boom again._
       | 
       | I can't agree with the author's conclusion. Besides, they don't
       | really make an effort in their article to tie the development of
       | supersonic flight over land to economic growth. This is more of a
       | "build it and they will come" conclusion. I don't buy it.
        
         | macintux wrote:
         | > A ban on supersonic flight over US soil is not a ban on the
         | development of the technology.
         | 
         | I am not defending the author's economic arguments, but this
         | sentence is quite dubious.
         | 
         | Who's going to spend millions (or billions) of dollars
         | developing better supersonic technology when one of the most
         | important markets is off-limits?
         | 
         | (Edit: remove superfluous word.)
        
           | frompdx wrote:
           | _Who 's going to spend millions (or billions) of dollars
           | developing better supersonic technology when one of the most
           | important markets is off-limits?_
           | 
           | Militaries, for one. But that doesn't mean supersonic flight
           | is completely off limits to passenger flight. There used to
           | be regular flights across the Atlantic at supersonic speeds
           | operated by Air France and British Airways. The last one was
           | in 2003. Did the Concorde program fail because they couldn't
           | fly over the CONUS?
        
       | panick21_ wrote:
       | Isn't the whole problem with boom shaping that it requires a
       | thinner fuselage meaning you transport even fewer people? I just
       | don't see this being viable.
       | 
       | Musk has talked for a long time about a supersonic jet that would
       | fly higher and thus not be heard on the ground. However batteries
       | would need to get quite a bit better still and it would be a
       | massive expansive project.
        
       | gabereiser wrote:
       | I live on my sailboat near Cape Canaveral, FL. I hear sonic booms
       | when SpaceX lands their Falcon9 back on the pad. 1) it's never at
       | night, usually on weekends or evenings (thank you SpaceX!). 2)
       | It's an awesome feeling but can leave the less healthy feeling a
       | bit distraught. 3) Because they are able to land a stage 1 back
       | at the pad, and that is a huge feat of engineering excellence,
       | I'll allow it. So awesome!
       | 
       |  _edit_ my point is there are people that aren't as bothered by
       | it as others and would like to see us do great things as a
       | species
        
       | lumb63 wrote:
       | The glaring issue I see with this proposal is the author supposes
       | that people who say that they could "live indefinitely with sonic
       | booms" have all the facts needed to make that assessment and are
       | correct, or that they want to live indefinitely with sonic booms.
       | 
       | People could "live indefinitely" with ionizing radiation (and
       | non-ionizing, I might add), but that does not mean it does not
       | impact their health or wellbeing. There are detriments outside of
       | the immediately obvious "loud noise bothers someone", such as
       | property damage, ecological destruction, environmental concerns,
       | health impacts, passenger safety, etc.
       | 
       | I couldn't disagree more with this.
        
       | thejenk wrote:
       | > Not a noise standard, which would make sense. A speed limit.
       | 
       | Is enforcing a perceived noise, or even a measured decibel limit
       | on the ground even realistic? It would be difficult to
       | investigate reported infractions unless they're consistently
       | coming from a scheduled route, because the noise level on the
       | ground depends on more than just the plane. "Supersonic jets that
       | don't have a lot of headroom on the noise limits in a dry, flat
       | desert shouldn't fly supersonic through this area because the the
       | land underneath is shaped like a parabola and it's very humid."
       | is much more difficult for a pilot to manage and a regulation
       | body to enforce than "Don't fly faster than this airspeed."
       | especially when the effect was the same back when the bill was
       | introduced.
        
       | hn_throwaway_99 wrote:
       | > issued a rule that remains one of the most destructive acts of
       | industrial vandalism in history.
       | 
       | Excuse me while I throw up in my mouth. Seriously, f this guy. I
       | suppose he's in favor of letting us chuck all of our garbage out
       | of open windows while we drive, too.
       | 
       | I've heard sonic booms before at air shows, and it's not some
       | quiet little "beep". They're loud and disturbing. As someone who
       | values silence, hearing these frequently at any hour of the day
       | would drive me insane.
       | 
       | I don't doubt there is technology that can make booms quieter,
       | but until it's 0, STFU. Sick of people arguing that creating
       | technology for the benefit of a tiny few (as others have
       | mentioned, supersonic travel will always be inherently more
       | inefficient) is OK, the externalities on the rest of the populace
       | be damned.
        
         | yinser wrote:
         | Tell me you didn't read the paragraph without saying you didn't
         | read the paragraph. By your own admission the sound is the
         | problem. The author states the rule should've been written
         | around sound levels not speed levels. You are governed by
         | emotions
        
           | notahacker wrote:
           | The author doesn't make a particularly good case for it
           | though, because it's relatively straightforward to define
           | whether an aircraft is or isn't exceeding Mach 1 (and even
           | more straightforward to stay well below it), whereas decibel
           | levels from a sonic boom depend on the position of the
           | observer amongst other things, and what's "acceptable" is as
           | the article discusses still a research problem. Non-US
           | markets and airframers exist, a first generation Mach 1
           | airliner existed and failed to gain traction, people worked
           | on "low boom" supersonic airliner projects anyway, and if a
           | working implementation didn't remain purely hypothetical,
           | Congress is perfectly capable of amending a law.
           | 
           | He also misses the _much bigger_ impediment to supersonic
           | jets than a local rule in the US being fuel cost, most
           | amusingly when he points out that 1973 was the beginning of a
           | so-called Great Stagnation but somehow misses the oil embargo
           | and the resulting fears over fuel prices affecting everything
           | that decade, including killing the demand for Concorde in the
           | rest of the world and changing airframers ' focus to fuel
           | economy. I think when he's suggesting that only a "vocal
           | minority" (which exceeded the number of people ever to have
           | experienced the rich person's pleasure of supersonic flight)
           | held us back from linear progress in commercial aviation
           | speed so we'd all be flying around at Mach 4 by now, he's
           | also being governed by emotions.
        
           | hn_throwaway_99 wrote:
           | I did read it. Most of it was arguing "Hey, it's not that
           | bad, we did some tests and only a few folks were really
           | bothered about it, and some people are bothered by anything,
           | so screw them!"
           | 
           | If I decide to go live in the middle of nowhere for some
           | solitude, I shouldn't have to defend my choices to enjoy that
           | solitude as "you're just too sensitive!".
        
             | yinser wrote:
             | So you admit then that a speed limit was a poor rule and it
             | should've been a sound rule and your vitriol was
             | unjustified?
        
         | fwlr wrote:
         | "I've heard sonic booms before at air shows, and it's not some
         | quiet little "beep". They're loud and disturbing."
         | 
         | I highly doubt you've heard a sonic boom at an airshow, it's
         | illegal to perform them and has been for a long time. A true
         | sonic boom performed at low altitude at an airshow would blow
         | out the eardrums of every attendant at the show and all the
         | windows in every car in the parking lot. Only the military is
         | allowed to cause them and only for very good reason. There was
         | a recent case in the UK where fighter jets caused a sonic boom
         | as they were scrambled to respond to a malfunctioning plane;
         | the video is here https://m.youtube.com/watch?v=fGR96Zz0dXk and
         | it had people from over 20km away calling the police to report
         | that a bomb had gone off somewhere nearby.
         | 
         | What you've heard at airshows is _close_ to a sonic boom, it's
         | called "tickling the cone" and it's highly compressed but _not_
         | collapsed sound waves. It resembles the regular roar of an
         | airplane, but packed into a few seconds. Very different to a
         | sonic boom, which sounds exactly like an explosion.
         | 
         | (The practical upshot is this strengthens your argument.)
        
         | sillysaurusx wrote:
         | Ok, and from the other side of things, I've never heard a sonic
         | boom in my life. No idea how loud it is, or what the tradeoffs
         | are. Shouldn't we get a say?
         | 
         | More generally, bans on a technology "forever" just seem silly.
         | It should at least be revisited every decade or so. A decade
         | brings lots of advancement; maybe there's some clever way of
         | minimizing the boom from a sonic boom now.
         | 
         | Or maybe there isn't. But it's not nearly as clear cut as "if
         | it's >0, ban it. No noise whatsoever!" Like... you've heard
         | loud motorcycles. Why not argue for those to be banned too?
        
           | sroussey wrote:
           | A sonic boom is quite loud and will shake all the windows of
           | every home across a state (though only a smaller section of
           | the state if it is large like California).
           | 
           | I have not heard them since the Space Shuttle was retired.
           | 
           | I agree with the forever part in theory. However in politics
           | (and law) if you leave a door slightly open, then people are
           | incentivized to open it wide open and "get around" various
           | rules.
           | 
           | Permanent "for forever" laws and never that. They are forever
           | until someone changes them. That's more binary and easier to
           | reason about than "this sonic boom is better than that sonic
           | boom so it's ok, and it the 1980s already so let's have at
           | it!". You set some threshold number, then the politics is
           | about the number not the booms themselves really.
           | 
           | If technology has truly advanced enough, people will change
           | the laws. Done.
           | 
           | Now as an engineer, I prefer the threshold. But it's so much
           | easier to change that. You start a company in 1980 and have
           | so much better tech after 10 years in 1990, but it doesn't
           | materially change things enough, so you shut down or try and
           | change the threshold. What do you do?
        
             | sillysaurusx wrote:
             | Implying we have any control over the laws. :) It's
             | lobbyists all the way down. Outsourcing our freedom to
             | lobbyists seems like a bad idea in almost every case.
             | 
             | "Just change the law" is usually not an easy proposal. One
             | could argue that it shouldn't be. But technology advances
             | much faster than the law, and having a lag time of decades
             | doesn't seem optimal in most cases.
        
         | lagadu wrote:
         | You went to airshows where the show was being performed at
         | airliner cruising altitude of 30-40k feet?
        
         | drewg123 wrote:
         | Did you actually read the article?
         | 
         | He's proposing allowing sonic booms below certain decibel
         | limits that are apparently below what any aircraft can achieve
         | today. So your experience with airshow sonic booms is not
         | directly relevant.
        
           | sroussey wrote:
           | Once that's a law, it's super easy to get politicians to
           | alter that number a bit more your way every year. That won't
           | make news or cause pushback that a binary decision makes.
           | 
           | No, the better thing is to demonstrate the lower number as
           | achievable first, then change the rules to go into
           | production.
        
             | yinser wrote:
             | Are you a politician or want to qualify anything you just
             | blabbered by showing FAA standards and the influence of
             | elected officials on their rules?
        
         | mastax wrote:
         | Were those sonic booms from airplanes at cruising altitude, or
         | from low flying jets showing off?
        
         | eviks wrote:
         | Non sonic boom noise from the airplanes > 0, ban them all?
        
           | SkyMarshal wrote:
           | You only hear them if you live near an airport, and only if
           | you're right under the landing approach or takeoff route. But
           | not when they're cruising at 30,000ft, or even if you live
           | within visual range of the airport but not under the
           | takeoff/landing path.
        
             | denton-scratch wrote:
             | The French used to fly Mirage jets over the sea near where
             | my family used to go on seaside holidays - no airport
             | anywhere near. I don't know what altitude they were flying
             | at, but you could see them clearly - as long as you looked
             | at the opposite side of the bay from where the sound came
             | from.
             | 
             | To be clear, they boomed, and it was loud and annoying.
        
               | SkyMarshal wrote:
               | Fwiw I was thinking of passenger jets, not military
               | planes. I don't have a good sense of how loud or quiet
               | the latter are.
        
             | eviks wrote:
             | So what? The 0 rule is more compassionate than you are, so
             | it cares about the groups of people you mentioned too!
        
       | Bloating wrote:
       | Taxes! Raise Taxes! But, just raise that other guys taxes
       | 
       | and, it needs to be cheaper
        
       | jedberg wrote:
       | I think a lot of people here are missing the author's point. It's
       | not about letting people go faster per se. It's about the fact
       | that the ban doesn't actually target the right thing.
       | 
       | The purpose of the Mach 1+ ban is to reduce noise. But if the
       | goal is to reduce noise, why not just set noise limits? We have
       | the ability to measure noise, so if the goal is to reduce noise,
       | set a limit on noise.
       | 
       | Then let the airplane operators innovate however makes sense for
       | their business. If you're worried about pollution (which is a
       | good thing to worry about!) then there should be a separate fuel
       | per mile limit or a carbon tax. Then they can innovate within
       | both constraints.
       | 
       | But the whole point is that the metric being used is wrong -- it
       | should be noise output, not speed.
        
         | TinkersW wrote:
         | Author never stated what the current noise level is, but in my
         | experience when I'm in the middle of nowhere and a jet passes
         | over at cruising altitude, I pretty much can't hear it
         | 
         | If this changes it so that this is no longer true, then no,
         | screw this idea.
         | 
         | Plus the reality is it would just be used by rich people to jet
         | about, probably emitting much more c02 per mile.
        
         | ccooffee wrote:
         | This is a good summary of the author's point. In a historical
         | context, it may be the case that the only useful way to enforce
         | "quiet skies" was to put a speed limit, but that doesn't
         | account for changes in technology that may enable quiet booms.
         | 
         | Most commenters in this thread seem to take issue with the
         | author's assumption that there is no other justification for a
         | speed limit other than noise reduction.
         | 
         | Honestly, I find the author's premise to be vaguely reasonable,
         | but the whole thing is undermined by the god-awful chart which
         | extrapolates historical aircraft speeds to imply that without
         | the "speed limit" rule, we would have commercial aircraft
         | crossing the Atlantic Ocean at 2500 mph. (Per wikipedia[0], the
         | fastest manned aircraft in history, a SR-71 blackbird flight,
         | capped out below 2200 mph.)
         | 
         | [0] https://en.wikipedia.org/wiki/Flight_airspeed_record
        
           | jedberg wrote:
           | Yeah this is a good point. The military was never capped by
           | speed limits nor fuel costs or pollution limits. And even
           | they didn't go faster than 2200mph as far as we know.
           | 
           | Which either means there was no reason to figure out how to
           | go faster, or they just couldn't do it. If the former, maybe
           | with commercial pressures there would be a reason to go
           | faster, but that's unlikely. And with the latter, well I'm
           | not sure a commercial entity would out-innovate the military-
           | industrial complex.
        
             | hughw wrote:
             | "as far as we know" -- they're famous though for trotting
             | out the Blackbird and setting a new public speed record
             | just exceeding whatever the Soviets had previously
             | advertised.
        
       | flerchin wrote:
       | In any spot in the country, you can look up and see aircraft, or
       | contrails, every day, all day. Unless near an airport, you
       | generally do not hear them at all. Even with boom reduction
       | technology, booms would be heard by everyone, everyday. This is
       | _not cool_. The author makes a valid point that the restriction
       | should be on the noise generated, not the speed, but even the
       | mitigated booms would not pass a reasonable test.
        
         | dghlsakjg wrote:
         | There is also the qualitative aspect.
         | 
         | I live near an Air Force base that luckily doesn't do
         | supersonic stuff.
         | 
         | Constant white noise, even at a pretty high level is something
         | that can be tuned out pretty easily.
         | 
         | I'm not sure the same can be said of singular events like a
         | sonic boom.
         | 
         | I think of it like the difference between a lawnmower half a
         | block away, and a subwoofer the same distance.
        
       | dghlsakjg wrote:
       | It was never all about the noise, SST/Concorde failed on cost.
       | 
       | Sure it would be cool to fly across the continent in 1/2 the
       | time, but not at the expense of tens of millions of people having
       | to know about it
        
       | shpx wrote:
       | > He was briefly startled but went back to fishing in under one
       | second.
       | 
       | This was laugh-out-loud funny to me, something a character on the
       | Silicon Valley show would say.
        
       | jmclnx wrote:
       | Well I am old enough to remember the Sonic Booms. We would get a
       | warning in the local newspaper (sometimes) and as kids we will
       | watch outside waiting for the boom and try and find the plane. We
       | lived fairly close to a base that would test these planes.
       | 
       | But, some people's windows would crack and some would break due
       | to the boom, which they had to pay for. So, if this limit is
       | changed, will the aircraft owners pay people for their broken
       | windows.
       | 
       | Back then seeing a plane at any speed was not common event. Now
       | you look up at just about any time of day and the chances are
       | very good (like 90%+) you can find a plane.
        
         | tpmx wrote:
         | Can I ask; roughly speaking, how old are you? (Or rather: when
         | was this?)
        
           | [deleted]
        
           | smolder wrote:
           | This is pretty easy to deduce given GP was a kid in the time
           | leading up to the 1973 rule.
        
             | lambdaba wrote:
             | GPT-4:
             | 
             | > It is difficult to pinpoint the exact age of the person,
             | but we can make an educated guess. The individual is
             | discussing sonic booms and mentions that, as a child, they
             | lived near a base where planes were being tested.
             | Supersonic flight testing and sonic booms were more common
             | during the 1960s and 1970s. If the person was a child
             | during that time, they could be in their 50s or 60s, or
             | possibly older. However, without more specific information,
             | it is not possible to determine their precise age.
             | 
             | Nothing extraordinary, probably because we've gotten so
             | used to it so quickly ;).
        
               | tiedieconderoga wrote:
               | Oof. I really hope we aren't moving towards a world where
               | people start to copy/paste verbose AI-generated
               | paragraphs without checking the results. Especially not
               | to answer simple questions like, "about how old is
               | someone who was a child 50+ years ago?"
               | 
               | The AI's guess is off by about a decade. If GP remembers
               | multiple booms, they were probably at least 10 by the
               | 1973 ban. Most people can't recall memories back to the
               | moment of their birth, but LLMs often ignore nuanced
               | contextual facts like that. Or maybe this is another case
               | of the model living a few years in the past, since
               | there's a lag in being trained on new data.
               | 
               | Who knows, but I am troubled that its incorrect answer
               | was so readily accepted. This is not an important
               | question, but it would have been easy to double-check.
               | This comment may be a grim portent of things to come, if
               | people continue to trust these models so implicitly.
        
           | jmclnx wrote:
           | As someone said I am a "sonic boomer" :)
        
             | tpmx wrote:
             | Thanks! :)
        
         | Y_Y wrote:
         | Ok, sonic boomer
        
         | davidw wrote:
         | I don't really care much one way or the other, but the article
         | does address this.
         | 
         | The actual externality is the noise/pressure wave, not the
         | speed. It makes sense to regulate as close to externalities as
         | possible, rather than banning sort of related upstream things.
         | 
         | In other words, if they can do supersonic without booms that
         | cause problems, go for it. If they're unable to, well, then
         | they keep flying so as to not produce them.
        
           | jmclnx wrote:
           | I saw that, I find that hard to believe unless they are
           | flying extremely high. I think height was also mentioned.
           | 
           | But doesn't flying that high damage the ozone or something ?
           | I thought that was one of the many reasons the concord was
           | stopped (Yes, I know the real reason was financial). If so,
           | many planes flying that high could cause other issues.
           | 
           | But some people will see if this happens.
        
           | Y_Y wrote:
           | What an unusually sane point.
        
           | wrigby wrote:
           | I can only assume you're being downvoted because folks are
           | thinking that you can't go supersonic without making a boom.
           | While this may be true, it doesn't change the fact that you
           | make a good point - regulation should be made as close to
           | externalities as possible. If it makes the upstream thing
           | impossible, then fine, but let's actually regulate what we
           | want to regulate.
        
         | wingspar wrote:
         | Yes. Experienced numerous Space Shuttle sonic booms. For me
         | they weren't problematic like broken windows. But would wake
         | you up. I also remember waiting for the sonic boom from
         | Columbia, which never came..
        
           | brycewray wrote:
           | Am in north Texas. That morning, I was watching NASA TV's
           | coverage of what should've been the mission's safe ending,
           | and heard multiple sonic booms, closely spaced. This was soon
           | after Houston had lost comms with Columbia following the
           | warnings about weird sensor readings, and I said to myself,
           | "That's weird. That sounds like what a shuttle does when
           | it's--" . . . and then I stopped, as I slowly began to
           | realize there might be a terrible reason _why_ Houston had
           | lost contact.
        
         | Procrastes wrote:
         | My wife used to live on Edward's Air Force Base which has been
         | a reserved sonic boom corridor all along. Just some learnings
         | for that lifestyle. Don't keep fragile things on narrow shelves
         | and you have to glue the bottom of every picture to the wall.
         | Don't have dogs or get them a xanax prescription. Cat's don't
         | care. It's not (always) an earthquake when the glass rattles.
         | And you get used to all of it.
        
       | 2-718-281-828 wrote:
       | if that restriction is lifted then the sonic boom is going to be
       | the next status symbol of the top .1%ers.
       | 
       | also - can someone give a tl;dr why that guy is so passionate
       | about that to begin with?
       | 
       | > I'm struck by the fact that American economic growth went off
       | the rails in 1973, the same year the overland ban on supersonic
       | flight came into force.
       | 
       | seems like is onto something ...
       | 
       | > The speed limit cannot be responsible for the entirety of the
       | Great Stagnation, of course.
       | 
       | oh, really, no kidding?
        
       | verandaguy wrote:
       | This article comes off as _very_ optimistic, to the point of
       | making some really bad assumptions and misrepresenting data.
       | 
       | The bit about sitting in a sonic boom simulator chamber is just
       | silly -- the author's subjective opinion about the loudness of a
       | sonic boom has no bearing on reality, and fails to factor in that
       | sonic booms during e.g. Bongo II (1964) shattered windows not
       | because of the sheer volume of the sonic booms, but because this
       | pressure wave would strike the large surface area of a window
       | nearly all at once, putting a fair amount of energy into it in
       | doing so.
       | 
       | Almost as silly is the line extrapolating speed trends in
       | commercial aviation over time; it reads like xkcd#605. It
       | completely ignores the different regimes of high-speed flight and
       | the limitations posed by it. 2,500mph is roughly Mach 3.2 at sea
       | level, or nearly 3.8 at 60,000ft. At Mach 2, you need to start
       | seriously considering thermal issues caused by friction related
       | to parasitic drag and the paint/coating of the aircraft; at Mach
       | 3, these become primary design constraints, and active cooling
       | systems have to be deeply integrated into the airframe. This is
       | to say nothing of the exotic engine design decisions that have to
       | be made in these regimes.
       | 
       | Much north of Mach 4, transporting any useful load becomes
       | borderline impractical in-atmosphere with current technology.
       | 
       | Ignoring fuel economy issues since I brought this up in a
       | separate comment: since the introduction of the Concorde, the
       | major focuses of aviation development have been on safety,
       | reliability, and automation (all of which are strongly linked).
       | "We live in the safest era of aviation in history" is an
       | evergreen statement thanks to those advancements, and aviation
       | incidents -- while tragic and unfortunately not completely
       | eliminated yet -- claim fewer lives with each passing year (as a
       | proportion of passenger-miles travelled).
        
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