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About SinBad

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    Spacecraft Engineer

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  1. the only real world monopropellant piston engines i know of are torpedo motors they are external combustion axial piston engines. the monopropellant is burned in a combustion chamber and the gasses are routed through the engine. the motor itself is really more of a high speed, high torque compressed air motor. only the compressed air is the high pressure combustion products rather than stored air. on a side note, the fuel (and exhaust) for these things is not something you want to have anywhere near anything biological. nasty stuff.
  2. modern heavy weight torpedos are quite smart weapons. purely from an engineering perspective, they are closer to autonomous submarine robots than the dangerous to use dumb weapon most folks think they are. if properly set up they will way point their way to a target box (an area designated by the user as the area within which the target should be, but non-targets wont be), then try to locate the target using a combination of active and passive sonar. they can even go a further step and be set to identify the target by listening for the unique frequency combinations of that vessel. once acquired, the torpedo will work out where the target is and where its going, then plot its own intercept course aiming at the estimated centre of mass. only when its on the final leg of this course will it arm the warhead. this can be triggered a number of ways based on the torpedos position, depth, the targets magnetic signature, the acoustic changes as it passes under the target. oh yeah, torps dont hit anything. not on purpose. they explode under the keel of the ship making a massive shock wave that lifts the centre of the ship, which then falls into the huge cavitation bubble the blast made, then gets shoved upward again as the bubble collapses. this essentially breaks the ships in half like a toddler snaps a bread stick. if the weapon isnt happy with its position under the target, it will chose not to detonate and instead will try again by driving away and re-homing. if at any point the weapon leaves the target box it will shut down. if at any time it enters one of potentially many safety boxes, it will shut down. all the boxes can be made to move so a box can be drawn around a friendly passing through and made to move on the same course and speed. all this is what these things do without wire guidance. with wire guidance (assuming someone doesn't accidentally tell it bad info) they can be even more effective. also, not saying it isn't so, but satellite signals are quite hard to receive through a dozen meters of sea water with a necessarily tiny antenna... thats all in a huge death tube with almost half a cubic meter of sensors and computers. in a man portable, hand fire weapon you could probably load a set of defaults that would see valid homing most of the time. there is no reason that a 30cm long, 50mm mini torpedo couldn't be made. we have gyros and accelerometers that fit in coins, and computers small enough to process their information into inertial navigators as well. we also are able to pack quite a bit of digital audio processing into a tiny package. the only limitation i can see is the size of the acoustic transducers in the sonar. the smaller they are, the higher their lowest frequency is. lower frequencies have less attenuation than higher ones, so can make a longer range detection, but higher frequencies can detect smaller objects with greater accuracy. most likely such a tiny torpedo would have a detection range of 100 meters or so, but be quite accurate inside that range. thats not to say thats the max range of the weapon, just that thats the range at which it needs to get to before it can automatically home. so if you know that your target can move at 5m/s (pretty average swimming? i dunno? swimming is something for targets to do after they get hit) then if you fire at centre of mass you have 20 seconds before the target is 100m away from your aim point. assuming your mini torp can travel at 20m/s, that gives you a firing range of 400m. call it 350m to allow for the initial acceleration. of course the faster your target, the closer you have to be so it cant get out of the detection range before the torp gets there. you can add in fail safes: like if its within 100m of its firing position and moving towards it, it shuts down. mini torp: do-able.
  3. wait, @WinkAllKerb'' is human? all this time i figure it was a sophisticated chatbot. huh, the more you know... @Kosmonaught, depends on the source of your pain: foot caught in snare, 4/10 downstream current too strong to swim to spawning ground, 2/10 struggling to attain perfect symmetry with your web, 1/10 keep running into out of memory errors, 0/10 cant find the right tool for the job, 7/10 never ending dread at the inevitability of your own death 9/10 the universe is just, soooo big and soooo old. and nothing you could possibly do will ever leave a lasting mark on it 10/10 the above deconstruction of probabilities displays my understanding of what it is to be human. only a true human would be able to reach this level of comprehension.
  4. Look what we convinced our government to do! I'm both pessimistic and hopeful about this news. our government has a track record of underselling our tech industry potential in favour of mining, farming and retail. lets hope this is a new chapter for Australian Science instead of a one stop shop for other countries to purchase land for building launch sites.
  5. complete control over an element... but its Astatine.
  6. wrong side of the planet for me. but I saw a bunch of photos of folks of all ages and walks of life standing together and using pinhole cameras and dark lenses to look at the eclipse. and even a really cool shot of some pavers under a tree with hundreds of projected images of it (natures pinhole camera: leaves). but hey, I can't complain, we got skylab, so... and then there was a photo of a certain head of state just squinting up at the sun getting a great view of bare faced retinal damage...
  7. I dunno, I saw it pop up and thought of a funny (I thought it was funny) reply.
  8. its what they scraped off the crew capsule floor after that time they hit 45g on re-entry... the mystery is where the crew went, and where this goo came from...
  9. true, but are such systems capable of intercepting objects over the oceans? are such technologies in use in this scenario? if you came down over the pacific for example. purely ballistic, pulling out and into an ocean hugging randomly chosen direction as late as you can survive. then get out of the area as fast and as low as you can. would a shore based interception system be able to get ordinance on location fast enough to still find you there? remembering that at this time they need to intercept a supersonic/hypersonic (depending on how advanced 'advanced civilisation ' means) seaskimmer, or if they are really slow they need to find a stealthed sub sonic sea skimmer rather than the expected high speed high altitude target they were designed to locate.
  10. save the hiding for after reentry. come in fast and hot. fast and hot enough that interception during re-entry is near impossible. then hit the deck (under the radar) over a large ocean and do a few minutes at high speed to get away from the projected landing site. then you can slow down and start using more terrestrial stealth solutions. but at some point you are going to have to land and hide or dispose of the craft. thats probably the fiddly part as the farther it is from eyes, the farther you have to travel overland. the farther you need to go, the higher the need for a vehicle, which you either need to bring with you (making your craft larger) or have arranged to be waiting for you by some local agent, complicit or otherwise. if you want to be fancy you could re-enter at noon and use an ablater material that will emit the same spectrum as the sky, or do it over a storm (also good cover for sonic booms). the point is, they know something arrived, but they don't really know what, or where it is. after all, you have a whole planet to get lost in. even better if there is a high population that is used to strangers visiting from other cities.
  11. Dont underestimate infrared laser for blinding folks. They are more dangerous at lower power levels than visible lasers because they dont trigger the blink reflex, which at low power levels is often what mitigates the potential damage of visible light lasers. At a tangent, i personaly think microwave lasers (masers) are the way to go. Thanks to nearly 70 years of radar research, we are rather good at converting electricity into microwaves (much more efficient than lasers) with far less heat produced. We also have a lot of experience with redirecting, lensing, pulse modulation and beam forming at tens of megawatts of power output ( for systems that transmit that power output every few seconds without extraordinary cooling). Additionally, microwaves couple with metals very well so barring widespread use of tupperware branded plastc armours, more of the produced energy can be dumped into the target.
  12. line 1/10 error: index out of bounds. failure to create new instance of object: human. this is text displayed on a video device that was input by a human for the purpose of communicating to other humans the humanity of the human who originaly encoded this text.
  13. @cubinator your name makes a lot more sense to me now... I made a thing, things, for dinner. I took cold mashed potato, then mixed in an egg, some corn flour and lots of shredded mozzerella. Made it into ping pong sized balls and deep fried them. Ended up golden and crunchy on the outside, soft and fluffy inside with melted cheese stringing out with every bite. Made the homemade cheeseburgers kinda plain tasting in comparison though.
  14. where is the f-18? those things are incredibly manouverable. also, last I checked, the air to air combat requirement (the thing that makes it a fighter) for the f-35 had been dropped because it was so horrible at it.
  15. neutron stars involed in collisions would likely cause a gamma ray burst. as we are here to look at the debris, I reckon it wasn't a neutron star.