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Bill Phil

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Posts posted by Bill Phil

    What Are The Uses Of Magnetic Gases?

    in Science & Spaceflight

    Posted

    Magnetic gases?

    Hmm...

    Maybe magnetic nozzles for conventional rocket engines, if a performance benefit exists. 

    Gas core reactor containment is a big one - could even enable open cycle engines that don’t lose too much nuclear fuel. And if that’s possible then nuclear thermal turbojets (and ramjets) become more practical from a propulsion standpoint if specific power is high enough.

    Provided the limitations on magnetic gases aren’t too limiting.

    If it can be done efficiently and externally without too many consequences magnetizing air could enable a Wingless Electromagnetic Air Vehicle - provided air can be magnetized in the necessary way.

    Alternate Nuke Pusher Plate Shapes?

    in Science & Spaceflight

    Posted

    32 minutes ago, p1t1o said:

    I dont have all the info, but I do remember reading Orion material that explained that the pusher is a flat plate, rather than a "cup" or other more encompassing plate, to reduce the dwell-time of the hot plasma, reducing erosion. This does result in some reduction in efficiency, as the blast is rapidly diffused sideways, but the extra mass needed to reinforce a plate that extracts more impulse from the blast offsets the increase in thrust efficiency.

    If I remember correctly....

    I remember that some designs were shaped so that the plasma deflected outwards, reducing dwell-time further. Like an inverted cup, but a very slight curve. Or a truncated cone shape.

    Though that may not be particularly beneficial, except for plate lifetime.

    35 minutes ago, sevenperforce said:

    Shaping the charge doesn't make the blast not-spherical, it just makes one side of the spherical blast wave denser than the other so that you increase the total impulse delivered to the plate.

    I would argue that constitutes a non-spherical explosion - as the propellant will have less specific energy and thus expand slower than the vaporized components of the nuclear charge. So it'd be a sphere with a deformation like a cone carved into it. But a shaped charge doesn't alter the density of a region of the blast wave, it alters the total energy available to the propellant. But the propellant is likely to have less specific energy, though maybe it's possible to have an equal or greater amount.

    51 minutes ago, sevenperforce said:

    Reality is exciting! You can stay in reality and still do a LOT of cool stuff.

    Indeed. Reality has a lot of cool and exciting stuff. Usually a lot more than you'd think at first.

    Alternate Nuke Pusher Plate Shapes?

    in Science & Spaceflight

    Posted

    18 minutes ago, sevenperforce said:

    The plate needs to be a circle because the explosion is spherical.

    Well there is some indication that nuclear explosions can be "shaped" in some way. Not perfectly, of course, but...

    OP:

    At this point you could probably get away with a Mini-Mag Orion for in space flight and a nuclear turbojet/rocket (or a nuclear turborocket) for in atmosphere flight - though you'd want retractable radiators for the Mini-Mag Orion unless you use some really fancy technology.

    The Mini-Mag Orion could even be boosted fission - or even an antimatter initiated reaction like ICAN-II.

    So instead of a proper pusher plate you have a magnetically confined miniature explosion (or a big one...) and then use a magnetic nozzle to accelerate it out the back. This should be relatively easy if antimatter storage is safe enough for practical use. 

    If you're advanced enough to have antimatter then a magnetic nozzle isn't too much of an issue.

    The Space Review: 'Racing to where/what/when/why?'

    in Science & Spaceflight

    Posted

    Honestly, Apollo was a mistake. At least in the way we did it. 

    It was a great accomplishment but it was a program that only existed to prove a point - as soon as it was reasonably certain that Apollo would land on the Moon the budget was cut and further Saturn V orders cancelled.

    Meanwhile a much more methodical and capability based program would have served us better. Perhaps space stations and orbital manufacturing/construction followed by dedicated Lunar vehicles - something closer to von Braun’s proposals from the 50s or the Space Transportation System as originally envisaged. 

    Essentially we should have developed more capability - starting with LEO space stations, then stations in higher orbits (though the van Allen belts would be a problem), followed by a robust infrastructure to deliver large payloads anywhere in the Earth-Moon system, then a Lunar station, then a Lunar landing. And there’s still room to expand such a system to interplanetary missions.

    Shooting straight for the Moon ultimately hurt manned space exploration in the long term.

    Shower thoughts

    in The Lounge

    Posted

    3 hours ago, RealKerbal3x said:

    A zero-dimensional object would have no length, no width and no height, which would make it an infinitely small point.

    An infinitely small point can also be described as a singularity.

    Therefore a 0D object is a black hole. :o

    Not quite. A black hole has a singularity because of the mathematical system we use to describe it. But a singularity isn’t a black hole. It’s just when something approaches infinity - like density in the case of a black hole or some function in the case of math.

    If we get better models then it’s entirely possible that future black hole models will not have singularities.

    Shower thoughts

    in The Lounge

    Posted

    22 hours ago, Shpaget said:

    You know about the woosh and splash before the wormhole forms in Stargate?

    If OSHA saw that, they would have an aneurysm. 

    WOOSH.

    I love that part...

    more engines

    in Prelaunch KSP2 Discussion

    Posted

    Almost all FTL schemes are problematic on the scales necessary since our theories don’t work on those scales. Warp drives require spacetime structures so small that GR doesn’t adequately describe them. Similar issue with almost every other FTL system.

    Our theories literally don’t describe these situations - impossible or not, we can’t really model them. Quantum gravity would help a lot, but it may not be enough.

    We may never have an answer...

    Or maybe we’ll get one in 50 years.

    Colonizing the Moon is more interesting than Colonizing Mars, what do you think?

    in The Lounge

    Posted

    I think industrializing the Moon is worth it - but it should be a place to work, not to live.

    Rather, human settlements in space should be free floating habitats. Any human carrying object will be inherently artificial - so why bother even building on the surface of the Moon when you can create your own gravity? With efficient and cheap energy it wouldn’t take much to catapult materials into space from the Moon (in energy terms), and then the material can be captured and processed in space. 

    Of course this has issues too but we can solve the lack of gravity and we can make comfortable settlements.

    Building Starfleet The Hard Way

    in Science & Spaceflight

    Posted

    1 hour ago, Terwin said:

    If you have ample AM you can make the boom so small that you can contain it on the vessel itself. 

    The whole reason you need a pusher-plate(ie orion-style) is that you can't make fission bombs small enough to contain on the vessel, and need to use shaped-charge nukes to throw some dense material to bounce off a 'pusher-plate'.

    Ample MA gives you torch drives(assuming you can handle the waste-heat) which is so far superior to Orion that it is hard to compare them.  Using AM for Orion is like using black-powder based bombs with a pusher-plate instead of liquid fuels.  Sure you can do it, but it is so wasteful that it makes no sense.

     

     

    Well there is one other advantage:

    A pusher plate makes no attempt to contain high temperature propellant. This lets you use very high temperature propellant which is why an external system like a pusher plate is actually quite good - a similar proposal to Orion using a large internal chamber with the propulsion units had much lower isp despite immense energies. The temperature was limited.

    Now it is possible to use magnetic nozzles and other such things to contain high temperature propellant but it’s far easier to just build a slab of steel.

    Since the Orion doesn’t contain hot propellant you only need radiators for the other on board systems - boosting performance (assuming highly advanced radiators aren’t available). The temperature change for the plate can be made quite small due to the short period of contact.

    So while the boom can be made smaller and something like Mini-Mag Orion could be built using AM, a pusher plate will likely be easier. It also enables larger thrust power.

    Is There A Way In Physics To Push Off Vacuum?

    in Science & Spaceflight

    Posted · Edited by Bill Phil

     This may be possible in an absolute sense but you don’t escape the rocket equation.

    The rocket equation can be converted to be a function of energy ratio and specific impulse - but in terms of impulse per unit energy. This creates a problem - you still have something similar to a rocket, essentially. The propellant isn’t internal though. But the energy used is.

    Thread to discuss negative things in a very general way, just see where it goes y'know?

    in The Lounge

    Posted · Edited by Bill Phil

    3 minutes ago, Dirkidirk said:

    wHaT DAT? a ThICK BOI

    No, the particle was a very smol boi. 

    It was just going so fast that it’s Lorentz factor was 320 billion, meaning that if an observer was at rest relative to the particle they would observe Earth to be 320 billion times smaller along the direction of motion. 

    Gotta wonder if the particle had flames painted on the side...

    Thread to discuss negative things in a very general way, just see where it goes y'know?

    in The Lounge

    Posted

    52 minutes ago, Dirkidirk said:

    there was a point in my life (6 months ago), when I thought "hey, maybe the earth is flat"(dumb, I knew). I then thought that that was dumb, so I searched up "flat earth logic", and found this:

    https://creation.com/refuting-flat-earth

    now I can no longer think of flat earthers as 'human' 

    Well the Earth would be as thin as a sheet of paper relative to the Oh My God particle...

    FTL travel/special relativity

    in Prelaunch KSP2 Discussion

    Posted

    18 minutes ago, mcwaffles2003 said:

    But for those ships that reach 30-40% c they are experiencing increased mass during that climb to those velocities, and if it were not for relativistic effects they would be going a fair bit faster

    Eh. 

    The difference between 0.4c and 0.43c (calculated using the Newtonion kinetic energy formula after finding KE at 0.4c using relativistic kinetic energy) is small enough that it likely won’t affect gameplay.

    Not to mention having to add in a ton of reference frames and Lorentz transformations between ships, planets, and so on.

    It really isn’t worth doing.

    what places in the solar system should we visit after mars and moon

    in Science & Spaceflight

    Posted

    2 hours ago, magnemoe said:

    Expensive however. you need to build, launch and maintain them around mars,  will mass more than the mars base. 
    Now if you make fuel and oxidizer you could burn that, if its an storm shortly after landing you die. 
    Face it if you want to stay on Moon, Mars or the belt and outward you need nuclear. 

    Not much of an problem, the small reactors who will be used is smaller than the ones on nuclear submarines, they will not meltdown as their mass is too low. 
    Space is so radioactive anyway and its no environmental concerns, just the health of the colonists and the habitates. 

    I doubt it’ll mass more than the Mars base - there are some very interesting technologies for light solar in space. 

    The real issue is the rectenna and the microwave transmitter...

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