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  • #16
    Originally posted by Swansong View Post
    sonic booms are illegal over the continental US.
    I have a dumb question. Sonic boom occur when you break the sound barrier. Does anything happen when you drop back under it?

    Edit: it really was a dumb question.

    A sonic boom does not occur only at the moment an object crosses the sound barrier and neither is it heard in all directions emanating from the supersonic object. Rather, the boom is a continuous effect that occurs while the object is travelling at supersonic speeds and affects only observers that are positioned at a point that intersects a region in the shape of a geometrical cone behind the object. As the object moves, this conical region also moves behind it and when the cone passes over the observer, they will briefly experience the "boom".
    So. Never mind.


    Last edited by Kepler; 09-06-2023, 10:35 AM.
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    • #17
      Originally posted by Swansong View Post

      This is a huge thing, in my opinion. To wit: in the 1960s we really pushed supersonic flight for bombers and spy planes, right? We got some great jets and incredible research out of them. But the XB70 was shelved and the SR71 only used by the CIA. Why? Both had major issues that were in the process of being worked out (or worked out to an acceptable level in the case of the SR71). But Just as the XB70 was really starting to get sorted out, ICBMs came online. And suddenly you don't need a jet to deliver that first strike. And once spy satellites really came into their own, the SR71 was retired (yes we still use newer versions of the U2, but that isn't remotely fast).

      I see the same thing with supersonic passenger flight. Society has accepted current flight times (customer service, comfort, scheduling less so), and with the rapid advancement in collaborative technology (zoom, office365, etc.) I just don't see a huge demand for economically sustainable supersonic flight. Smaller scale, supersonic business jets? Yeah sure, probably. But 200+ passengers that need to get 8000 miles in 3 hours that are willing to pay the accompanying cost? No.
      Agree with all of this. Just a nit that I don’t think anyone is contemplating 200-seat cabins. The most ambitious player today is Boom, and they’re looking at 55 to 75 seat cabins. Their sweet spot is really the NYC/BOS to LHR/LGW market, where it really would be possible to fly over for a lunch meeting and then return to sleep in your own bed that night.
      If you don't change the world today, how can it be any better tomorrow?

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      • #18
        Originally posted by Kepler View Post

        I have a dumb question. Sonic boom occur when you break the sound barrier. Does anything happen when you drop back under it?

        Edit: it really was a dumb question.



        So. Never mind.

        Sorry, but that's not a dumb question. Doing the research you did, it became obvious why supersonic flying over land isn't legal. So it was far from a stupid question.

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        • #19
          Originally posted by MichVandal View Post

          Sorry, but that's not a dumb question. Doing the research you did, it became obvious why supersonic flying over land isn't legal. So it was far from a stupid question.
          Oh, I get why it's no bueno, but my mistake was thinking the boom is one and done. It's a persistent phenomenon and the answer to what happens when you drop back under is simply "it stops."

          True, it wasn't a dumb question, it was an ignorant question, and now I'm all edumacated up.

          Also: edumacated does not show as a misspelled word, which means either it was in the dictionary or at some point I added it.
          Last edited by Kepler; 09-06-2023, 12:40 PM.
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          • #20
            Originally posted by MichVandal View Post

            Why do we need that? And I doubt the 3 hours from NYC to Tokyo unless the plane spends most of it's time above 100,000ft, as you can't break the sound barrier over land- so much of the trip would not be fast.

            But I still really fail to see the need of getting there that fast. For one thing, it will be really, really expensive- the plane will be a massive departure to construct it and the engines will need to be very new. So to just build the plane and keep it flying, it will be really expensive. On top of that, drag goes up so much with speed that the required fuel to get from A to B will be a massive increase. Basically, it will have to end up being just like the Concorde.

            And for the nominal person, what's the point?

            We need planes that are more efficient and cleaner not the opposite.
            Like this one:

            DAF selects JetZero to develop blended wing body aircraft prototype > Air Force > Article Display

            (Disclosure: my company, Northorp Grumman, is a partner on the project)

            The US Military consumes 10% of the US's jet fuel. According to the article, mobility (cargo + tankers) aircraft use 60% of that fuel. If BWB's could cut drag by 30%, that cuts US jet fuel usage by 1.8%. Once the type is in service, it should be a no brainer for the commercial cargo market - dollars and cents matter. Commercial passenger is a tougher sell - people like there being windows, but realistically, if you're in the center seat of a 3-5-3 777, you already can't see out the window and people accept that, so I think it could catch on.
            If you don't change the world today, how can it be any better tomorrow?

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            • #21
              Originally posted by LynahFan View Post

              Agree with all of this. Just a nit that I don’t think anyone is contemplating 200-seat cabins. The most ambitious player today is Boom, and they’re looking at 55 to 75 seat cabins. Their sweet spot is really the NYC/BOS to LHR/LGW market, where it really would be possible to fly over for a lunch meeting and then return to sleep in your own bed that night.
              You're right, and I knew that, but yeah. especially at under 100 passengers the cost on this would be astronomical.
              I gotta little bit of smoke and a whole lotta wine...

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              • #22
                https://www.thedrive.com/the-war-zon...ird-of-an-f-35

                yeah….you know what else was supposed to cost a quarter of an F-35?


                An F-35.
                If you don't change the world today, how can it be any better tomorrow?

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                • #23
                  Interesting.

                  European Union member states and lawmakers reached a preliminary agreement on what they touted as the world's first comprehensive AI legislation on Friday.

                  This landmark deal aims to regulate artificial intelligence (AI) technologies, including ChatGPT and governments' use of AI in biometric surveillance.

                  According to the European Parliament the new deal sets a global precedent as the world's first AI law, with the EU poised to be the first major region to implement such laws.
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                  • #24
                    < Flashes compunerd bat signal. > Hype or truly transformative?

                    "The good thing about graphene is, not only can you make things smaller and faster and with less heat dissipation, you're actually using properties of electrons that are not accessible in silicon. So this is really a paradigm shift — it's a different way of doing electronics," said de Heer.
                    That sounds... important.

                    Here's Nature to make me feel (more) stupid:

                    Abstract

                    Semiconducting graphene plays an important part in graphene nanoelectronics because of the lack of an intrinsic bandgap in graphene1. In the past two decades, attempts to modify the bandgap either by quantum confinement or by chemical functionalization failed to produce viable semiconducting graphene. Here we demonstrate that semiconducting epigraphene (SEG) on single-crystal silicon carbide substrates has a band gap of 0.6 eV and room temperature mobilities exceeding 5,000 cm2 V−1 s−1, which is 10 times larger than that of silicon and 20 times larger than that of the other two-dimensional semiconductors. It is well known that when silicon evaporates from silicon carbide crystal surfaces, the carbon-rich surface crystallizes to produce graphene multilayers2. The first graphitic layer to form on the silicon-terminated face of SiC is an insulating epigraphene layer that is partially covalently bonded to the SiC surface3. Spectroscopic measurements of this buffer layer4 demonstrated semiconducting signatures4, but the mobilities of this layer were limited because of disorder5. Here we demonstrate a quasi-equilibrium annealing method that produces SEG (that is, a well-ordered buffer layer) on macroscopic atomically flat terraces. The SEG lattice is aligned with the SiC substrate. It is chemically, mechanically and thermally robust and can be patterned and seamlessly connected to semimetallic epigraphene using conventional semiconductor fabrication techniques. These essential properties make SEG suitable for nanoelectronics.
                    Last edited by Kepler; 01-05-2024, 05:44 AM.
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                    • #25
                      Originally posted by Kepler View Post
                      < Flashes compunerd bat signal. > Hype or truly transformative?



                      That sounds... important.

                      Here's Nature to make me feel (more) stupid:
                      For now, I would still call it hype. Not that it isn't possible, there are a huge amount of areas where graphene has demonstrated that it is an incredibly capable thing- even the number of areas where it works is astounding.

                      The problem is that nobody has figured out how to mass produce it.

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                      • #26
                        Originally posted by MichVandal View Post

                        For now, I would still call it hype. Not that it isn't possible, there are a huge amount of areas where graphene has demonstrated that it is an incredibly capable thing- even the number of areas where it works is astounding.

                        The problem is that nobody has figured out how to mass produce it.
                        I thought this paper was exactly that: the way to do that to make them act like semiconductors?
                        Cornell University
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                        ECAC Champion 1967, 1968, 1969, 1970, 1973, 1980, 1986, 1996, 1997, 2003, 2005, 2010
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                        • #27
                          Originally posted by Kepler View Post
                          < Flashes compunerd bat signal. > Hype or truly transformative?



                          That sounds... important.

                          Here's Nature to make me feel (more) stupid:
                          I was working in 2014 with a Cornell alum Purdue professsor on the use of graphene in high-end aerospace batteries - its combination of electrical and thermal properties is darn near magical.

                          He’s still working on it….at UCLA now.
                          If you don't change the world today, how can it be any better tomorrow?

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                          • #28
                            Hurd says he was ‘freaked out’ by briefing while on OpenAI board

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                            • #29
                              Originally posted by Slap Shot View Post
                              Hurd says he was ‘freaked out’ by briefing while on OpenAI board
                              Yes, I imagine it was freaky, but

                              Indistinguishable from human cognition,
                              No, no, no!
                              Cornell University
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                              • #30
                                Will Hurd is a moron.
                                Code:
                                As of 9/21/10:         As of 9/13/10:
                                College Hockey 6       College Football 0
                                BTHC 4                 WCHA FC:  1
                                Originally posted by SanTropez
                                May your paint thinner run dry and the fleas of a thousand camels infest your dead deer.
                                Originally posted by bigblue_dl
                                I don't even know how to classify magic vagina smoke babies..
                                Originally posted by Kepler
                                When the giraffes start building radio telescopes they can join too.
                                He's probably going to be a superstar but that man has more baggage than North West

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