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Cake day: June 18th, 2023

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  • If you’re getting into private jets, you should also know that brands have reputations even there.

    Gulfstream is a luxury brand within the private jet world. You can easily get a comparable product from Bombardier or Cessna Textron that performs equivalently, but only pay half as much operating costs as Gulfstream. Like Gucci, you pay a lot of money just for the Gulfstream name.

    At the low end of the market, Honda makes a small jet. (This is in the Very Light Jet category which bumps up against the turboprop market).

    At the very high end of the market you get into Boeing Business Jets, and the Airbus equivalent. These are converting airliners to your exact interior design specifications. Airliners are like another order of magnitude higher cost to operate.


  • There’s a class of orbits called “polar orbits” that are sideways and perpendicular to the spin of the earth. These orbits are useful for satellites whose main job is taking pictures of earth, because they will cover nearly all of the earth’s territory over time. You get into a polar orbit by launching to the north outer south.

    Aside from that, nearly all launches go towards the spin of the earth, because it’s a free boost. The fancy rocketry word for this is “prograde”.

    The sun appears to traverse from east to west in the sky. This means that the earth is moving the opposite way: west to east. So if you want to take advantage of the free boost, the rocket needs to take off in an easterly direction.

    The amount of spin you get is greatest if you launch from the tropics near the equator, and it falls off at greater north or south latitudes. In theory, if you set up a launch pad at the north pole, the spin boost would be zero in all directions, because you’re just rotating in place. At the equator, the free boost is around 1000 mph or 1600 km/hr.

    So the ideal launch site is as close to the equator as possible, and it has low population off to its east, in case the rocket blows up or crashes. The United States has two sites that meet these criteria: one in Florida and one in extreme south Texas. Both of these face an ocean to the east. Europe launches Ariane rockets from French Guiana in South America. Russia uses Kazakhstan, which is on the southern ends of the old Soviet Union.


  • mkwt@lemmy.worldtoAsklemmy@lemmy.ml*Permanently Deleted*
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    1 month ago

    There was a book a while back called Guns, Germs, and Steel that delves into this topic.

    The root cause, as I understand it, is that Europe is on a continent oriented east-west instead of north-south. And Europe in particular is on the part of that continent that has a lot of easy access to the sea.

    East-west orientation allows you to transplant plants and animals long distances and keep them at roughly the same latitudes, which means roughly the same climate. That is a big boon for spreading “civilized” agriculture, which is what creates surplus of labor, which creates non food jobs that advance technology.

    Among the common 5-7 domesticated food animals people eat today, all but one or two were domesticated in Mesopotamia, but then spread all over Europe.

    Access to the sea is the other component that turns tech advantage into colonialism, because it gives the transportation. Even today, China and Russia are great powers, but they are forced to be continental powers instead of maritime powers, because nearly all of their coast lines are hemmed in by narrow seas that are easy to blockade.

    There are, of course, a bunch of other factors I’m not even thinking about and competing opinions. But I don’t for one second think that any of this has anything to do with European “innate intelligence” or skin color.



  • I gave you the downvote because I once attended a public lecture by Stephen Hawking, near the very end of his lifetime. It had to be one of the few, very last, public lectures that Dr. Hawking had in him. And the topic of that lecture was the nature of time, and how all of the equations of motion are fully reversible, etc, etc etc.

    Out of all of the topics Dr. Hawking could have discussed, that one is the one he chose. And to me, that means that the nature of time was interesting enough to him to spread around to the public. That there are live issues that are not well settled. And so on.

    Since that time, I’ve not seen any major developments in theoretical physics or philosophy to shift the status quo to an appreciable degree.

    This leads me to the final judgement on your comment: You are wrong. There are live issues to discuss here, and OP deserves to further explain, defend, and debate their philosophy.




  • If I recall correctly, the photon sphere orbit is unstable, so there may not be a ton of photons there. “Unstable” in this sense means that photons in adjacent orbits tend to diverge away from the photon sphere orbit rather than toward it.

    For Schwarzchild holes, the lowest circular orbit for massive objects is at 3 event horizons, which is above the photon sphere. There are unstable circular orbits down to 2 horizons. Black hole rotation reduces this altitude for prograde orbits asymptotically down to 1 horizon.



  • That’s not quite right. In sci fi there are rules that remain logically consistent, based on known physics or not. In fantasy, they can make up the rules as they go along.

    Compare Star Trek and Star Wars. Trek’s subspace field theory is not any kind of known physics, but Trek is still sci fi. Because the subspace fields are fairly consistent about what they do. Star Wars’ fan base damn near revolted when the series hinted that The Force might not be purely mystical.

    Sci fi doesn’t have to explain what the rules are to the reader. They just have to be be discoverable using the scientific method. Dragonriders of Pern is hard science fiction, originally published in Analog.







  • I am not a lawyer, and I am not your lawyer.

    Off the top of my head, I can’t really see where or how this is illegal in most US jurisdictions. In “at will” states you can be hired or fired at any time for any reason* or no reason. And likewise you can quit at any time for any reason or no reason. If you can be hired or fired based on this scam, you can be promoted or held back based on it.

    Having said that, this is really scammy, and I would not want to work there.

    *except discrimination based on: race, color, religion, sex, national origin, age (>40), or genetics. Likewise, retaliation for unlawful sexual harassment.


  • mkwt@lemmy.worldtoAsklemmy@lemmy.mlHow do I make a product?
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    6 months ago

    I work in engineering, sometimes with startup types that want to develop a “product”. I’m also a coinventor on some patent applications. This response will be based on US perspective and economics.

    1. First before all, do a patent search. This is to find out if someone already patented your ideas. If so, you either need to pay them royalties to license the patent(s) or rework your product to avoid the patents. Google Patents is highly accessible for this.
    2. Then, if you think you have original, patentable ideas, engage a patent attorney to do a “real” search and to work on filings. This will take money (at least 10s of thousands US) for the initial work. All the major legal jurisdictions are “first to file,” so it no longer helps to mail your notebooks to yourself for proof of date of invention. You have to at least file a provisional application to get a patent priority date. Keep everything top secret until you have that application. Execute non disclosure agreements (NDAs) with any outside firm or individual you talk with. 2b. As an aside, software is not generally patentable any more, on the grounds that math formulas are also not patentable. There may still be some ability to patent software-oriented ideas as business methods or the like. Just because the patent office issued a software patent doesn’t mean it’s enforceable. Courts hold patents to be invalid all the time.
    3. I want to impress upon you some view of the real costs of prototype design and what is known as “nonrecurring engineering” (NRE) in the biz. You don’t say, but it sounds like you want some amount of custom electronics coupled with some backend software. Costs can vary considerably depending on circumstance, but I would typically see 100k-300k USD in design and prototype build costs to get initial prototypes with some limited functionality for these components. It could very well take 1 million USD or more to get a more complete product design. This also depends a lot on how you engage engineering talent: turnkey consultants can be the most expensive, or you could save a bunch of up front labor cost by offering equity to a key designer. 3b. I don’t know how complicated this app is, but it’s not unusual for software engineering costs to overshadow the hardware engineering costs, and sometimes by a lot. This might be something to keep in mind if you’re contemplating app development up front paired with virtual hardware plans.
    4. A “virtual design” for hardware that is just drawings could be done for cheaper than the prototype quote I gave. I see common prices for that kind of work at least 10k and up to 50k depending on how much initial design work you want or need done (and how the talent is engaged, etc, etc).
    5. Manufacturing. Depends of course on what is going into your gadget and how many units you plan to build.
      5a. Custom PCBs can commonly be run in low volumes for relatively cheap. It’s more expensive to solder the components on than just to etch the boards. There are many board houses that let you turn in your design files and get a quote online. 5b. For startup that wants a low volume (~100) of some gadget, you might want to look into contract manufacturers. These will assemble your product per drawings, typically in a non-automated or low-automation fashion. For example, they might have pick and place machines and expensive wave flow solder machines to assemble PCBs, but then the boards are screwed into enclosures by hand. These places might run double or triple the per unit cost of a more automated setup, but it can still be the best option for low numbers of units. 5c. Overseas manufacturing can cut costs through reduced labor bills. The traditional hurdles in the startup environment are long shipping lead times (particularly by sea, 10-12 weeks not uncommon) and the added hassle and complexity of international business dealings. In the US particularly, the recent tariff situation is throwing a monkey wrench right in the middle of this, and I will not attempt to analyze the impact. 5d. A commonly surprising manufacturing cost: if using injection molded plastic for enclosures or the like, the custom molds can cost several 10s of thousands to build and store. This is a fixed cost, so it doesn’t impact the per unit for large volumes, but it is often an expensive hurdle in the total manufacturing process for small startups.
    6. Regulatory. It’s highly likely that any consumer facing gadget will need at least some regulatory testing, probably from a dedicated contract test house For example in the US, Underwriters Laboratory (UL) demands safety testing, and the FCC can require “part 15” testing and separate testing if you have a radio (such as WiFi or Bluetooth). As an exercise you could try looking up all of the various logos on the bottom of your favorite gizmo or in the fine print in the manual.

  • I’m pretty sure nobody registers their personal smartphone and laptop every time they leave the US for a vacation.

    I agree with you on this, but CBP is certainly within their legal rights to interrogate you on the origins of your personal electronics, and they can make a determination that your stuff is subject to duty if it’s over the limit and they don’t believe you are reimporting.


  • For residents of the United States the duty free limit when returning is 800 dollars worth of stuff. I believe that’s every thirty days. You usually have to answer whether you exceed this limit in the declaration.

    So you just go to Canada, buy the thing, unpack it from the packaging, and pretend like its just personal items. Just like a smartphone.

    If tariffs become a big thing, this will definitely happen more, but it will also get a lot more scrutiny from customs as well.

    AFIAK, border agents usually don’t ask if you bought your phone in the US or from outside, they shouldn’t ask about other personal electronics, right?

    Stuff that you exported and reimported for personal or business use, but not for resale, is exempt from duty with no dollar limits. If you want documented proof that you are reimporting, you can register the stuff at a customs office in the United States before you leave.