Duxwing

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About Duxwing

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  1. Duxwing

    People irritated by Space X launches

    Those poor people, living in a world of paranoia and superstition. May the light of reason one day reach these dark corners of their minds.
  2. Duxwing

    Unity analytics won't opt out?!

    You shouldn't have to go into the .cfg to switch a flag that has a button. As for whether Unity might break GDPR, half the reason big companies have all those lawyers is to stay out of trouble. The other half is for when they get into it anyway, and it happens all the time. Usually it's user forums where problems like this one are discovered. A good company will read about and fix the problem before the media does.
  3. Duxwing

    2 Different Graphics Cards in One Computer

    Thanks for the replies! You have persuaded me not to add the card unless I encounter bottlenecks years from now. In response... 1) I would add the graphics card myself but would need to move bundles of cables that were zip-tied together and secured to the case by Geek Squad when they upgraded my rig years ago. I might also need to move the hard drive and its cables, because the card would reach from the back of the tower to the front. I am not confident in doing this. 2) My power supply is 1,200 Watts. If it would not have enough power, then I doubt I could find a bigger one, much less fit it into my computer. It will have to do. 3) I too have noticed that Multi-GPU, whether enabled by the hardware of a bridge or the software of DirectX12 or Vulkan, is not supported by many games. That said, they are new. Would you mind showing me where you learned that multi-GPU is dying?
  4. Hey Forum, I found a graphics card on one of my shelves and want to install it alongside my current one to improve my game performance. Although the graphics cards are slightly different, precluding a bridge, I have read that DirectX12 lets game developers work around this problem by building games that can use several different graphics cards at once. Would installing the second card be worthwhile? Technical Details: -Current Card: GeForce GTX 780Ti 4GB -Found Card: GeForce GTX 780 3GB -Installation Cost: $40
  5. I can't find your mod on CKAN, ferram. Is something wrong? -Duxwing
  6. Thanks! Launch profile matters for all systems going beyond LKO, but I see your point. I meant, and my thesis turned out to be, that improving design can only improve cost per ton to the limit imposed by the payload and mission profile. This limit can be called the theoretical upper bound on the efficiency of any rocket system, whether for lifting or transit. Now that I think about it, we could state generally that the maximum efficiency of any engineering project with well-defined theoretical principles is given by applying them to the constraints of the project. In Kerbal Space Program, for example, the maximum cost-efficiency of using an LV-N to accelerate a payload would be given by applying the Rocket Equation to the relevant propellant fractions of the tanks, properties of the LV-N, etc.
  7. We can and should define this problem more abstractly. The cost per ton of a launch system equals the amount of money spent, per launch, to lift one ton of payload along a desired launch profile to a desired orbit. These latter two constraints are important because they prevent payloads from being launched by very cheap but very weak lifters, whose cost would approach that of fuel with increasing payload regardless of whether the system were recovered or air-breathing or not. Therefore, we must state the theoretical lower bound of efficiency in two lines rather than one. The first line must describe the aforementioned constraints, while the second line defines the efficiency as the payload mass divided by a cost function ultimately derived from the rocket equation. Working from the handy variables given by Abastro, we may write that this cost function must total the costs of the fuel, tankage, engines, and utilities. Cost (System) = Cost (Fuel, Tankage, Engines, Utilities) = F + T + E + U If, like Abastro, we assume that the cost imposed by each variable is a function of its associated mass, then we may derive these masses and thereby their associated costs from the rocket equation of our launch system. We will write the masses of our components as the lower-case versions of their costs. Therefore, where p is the mass of the payload, we may compactly write that, dV = Isp ln(mw/md) = Isp ln[(f+p+t+e+u)/(p+t+e+u)] exp(dV / Isp) = (f+md)/(md) f/md = exp(dV / Isp) - 1 The masses of the payload, engine, and utilities being given alongside the necessary dV and Isp by the first line of the statement of efficiency, we may consider e and u fixed and declare the lefthand side the mission constraint function k. f/(p+t+e+u) = k f = (p+t+e+u)k f - tk = (p+e+u)k Since we may assume that the mass of the tank equals the mass of the fuel multiplied by a propellant-mass-fraction proportion w, we may write, f - wfk = (p+e+u)k f(1-wk) = (p+e+u)k f = (p+e+u)k/(1-wk) Note that this equation shows, just as we would expect, that the mass of the fuel depends on the masses of the engines and utilities alongside the propellant-mass-fraction and the constraint function. This check lets us confidently declare that Cost (System) = F(f) + T(t) + E(e) + U(u) = F((p+e+u)k/(1-wk)) + T(wk) + E(e) + U(u) Of course, this definition of the cost equation requires the system to have only one stage, but summing it over each stage of a multi-stage system reveals the system's total cost. In addition, one may handle different types of fuels, tanks, and engines by considering each function and variable above a function with the numbered function and mass F1, f1, F2, f2 ... of each fuel or tank or engine type as its arguments. Lastly, to determine the efficiency, divide the payload by the cost. Notes for recoverable launch systems: Subtract from the cost of the tank, engine, and utilities the recovery function, which depends on internal KSP math and the mass of the recovered components. To include the startup cost of building the system, multiply the recovered mass amount by 1 - 1/launches, where launches is the expected lifetime of the system. Ignore this startup cost if you click the "Recover" button. Having determined the efficiency of our system and organized the mission constraints and engine and utility masses in the first line of our efficiency statement, we see that the efficiency of our launch system is already determined by the first line of our efficiency statement, which defines the mission constraints and thereby the dV, Isp, and masses of engine and fuel, which must be adjusted to satisfy them. For example, reaching Kerbin's orbit from its surface requires a powerful and therefore heavy first stage engine, decreasing efficiency. In conclusion, we discover that launch systems have only one efficiency, and that decreasing our cost per ton will therefore require different mission constraints rather than better mathematics. Launch profiles must be relaxed to accommodate more-efficient ascents. Payloads must be sent to destinations requiring smaller changes in velocity. And here we recognize that efficiency is merely one aspect of our space program, which must not only save money to do more things but also spend money to do anything at all. In essence: no bucks, no Buck Rogers. -Duxwing
  8. Duxwing

    Duxwing's Kerbal Poetry

    I've adapted another song!
  9. Duxwing

    A Question About Lavabit

    Dear Forum, Why was the founder of Lavabit, an encrypted email service company against which the United States government had obtained a search warrant in pursuit of the whistleblower Edward Snowden, not found in contempt of court and ordered to restore Lavabit after he defiantly shut it down? Although I deplore the whole affair of mass surveillance, I also cannot ignore that the government appeared to have legal means to pursue him personally for his services or, should that pursuit have failed, publicly punish him for opposing its agenda. Therefore, I seek the knowledge of better-read posters who could enlighten me about this subject. Points to Consider 1) The government's case against the founder was under seal, and the founder himself was under a gag-order and without adequate counsel, leaving the prosecutor able to make threats whose credibility or even legality the defendant obviously could not ascertain. Yet, the government did not exploit this opportunity to easily terrorize the hapless founder into submission. 2) The government must have known that it would later require the cooperation of other people, whom it must also have known could be moved by the example of the Lavabit founder. Yet, the government did not infer from this knowledge that his example would move them to cooperate only if he surrendered rather than, as he did, martyr himself and thereby inspire martyrdom. 3) The government had illegal but clandestine means to extract what it wanted from the Lavabit founder. Yet, it did not avail itself of them and instead availed itself of the court, where the founder predictably won a political and moral victory if not a legal one. With these points being considered, the government's decision to take the Lavabit founder to a federal court rather than a black site seems, although relieving, bizarre. So, why did the government do what it did? -Duxwing
  10. Duxwing

    Kerbal's attitude to nuclear power

    I never thought about the possibility of Kerbal nuclear weapons until now, so I figure Kerbals are peaceful. But they're still kerbal: it's easier to list the things they haven't blown-up!
  11. Duxwing

    Istandwithahmed

    Of course the kids are always innocent: the adults are responsible for them in every case. -Duxwing
  12. 12/12, though only because I eliminated the other three famous scientists for their contributions to physics, leaving Salk for the invention of the polio vaccine. -Duxwing
  13. Nonsense! Physics loves torch drives: an open-cycle gas-core nuclear-thermal rocket has enormous specific impulse and power. Atomic rockets says the minimum thrust-to-weight ratio is 1.8 and minimum specific impulse over 3,500s. The website continued that the theoretically-maximum power is almost 10,000 seconds thrust-to-weight ratio of 20. We could even use antimatter annihilation contained by electromagnets well-separated from the ship's payload. Radiation decreasing with distance squared, the separation would minimize heating, permitting such engines as earthbound observers might mistake for dying stars. Just mind the neutron flux and don't burst the tank! -Duxwing