allardjd 1,853 Posted July 1, 2015 Report Share Posted July 1, 2015 This implies acceleration is acting on the object continuously. In a vacuum, and independent of the mass of the object, other than from the initial force, without any gravitational force, or any other force acting on the object, it cannot accelerate. Aha - with that stipulated, I agree. However, the energy of any such initial force in a vacuum will eventually dissipate. I can't agree so readily with that one. Mr. Newton covered it in his first law of motion, "Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it." Terminal velocity is reached when speed is constant. In a vacuum, an object will initially accelerate at 32 ft/s2, up to a speed of 32 ft/s, and then remain constant. To your point, "...The velocity will continue to increase without limit at the rate of 32 ft/s2 until it runs out of space to free fall in...", even in the Earth's atmosphere, an object in free fall will ultimately stop accelerating, thus reaching its specific terminal velocity. That's just not the case. 32 ft/s is only about 20+ mph. An object dropped will quickly accelerate above that speed if it has enough distance to fall, unless it has a large area/weight ratio, e.g. a feather. In a vacuum, even that doesn't matter, which Galileo proved. Terminal velocity is entirely a matter of air resistance. In a vacuum, the concept has no meaning. The definition of terminal velocity is: "...the constant speed that a freely falling object eventually reaches when the resistance of the medium through which it is falling prevents further acceleration." In the atmosphere, near Earth, an object stops accelerating and falls at a constant speed when the air resistance it encounters at its current speed exactly balances the force being exerted by the Earth's gravitation. I got this information about terminal velocity for a human body from a skydiving site... "In stable, belly-to-earth position, terminal velocity is about 200 km/h (120 mph). Stable freefall head down position has a terminal speed of 240–290 km/h (around 150–180 mph). Further minimization of drag by streamlining the body allows for speeds in the vicinity of 480 km/h (300 mph)." Link to post Share on other sites
allardjd 1,853 Posted July 1, 2015 Report Share Posted July 1, 2015 a simple GPS or Wi-Fi jammer should drop the drone from the sky like a rock or send it back home WHAT? And jam my own Wi-Fi? Never. The GPS jammer idea has merit, however. It's thought that might well be how Iran got that US drone, with some help from their friends to the east. John Link to post Share on other sites
MyPC8MyBrain 273 Posted July 1, 2015 Author Report Share Posted July 1, 2015 lol, don’t be a baby; its just for few minutes; then it will come back there's a good chance you might win a drone Link to post Share on other sites
allardjd 1,853 Posted July 1, 2015 Report Share Posted July 1, 2015 there's a good chance you might win a drone I'd like that. Slightly used, half a sortie, only crashed once. Maybe I could start a trophy room. John Link to post Share on other sites
MyPC8MyBrain 273 Posted July 1, 2015 Author Report Share Posted July 1, 2015 John what did you eat today? did they readjust your meds? you’re cracking me up I’m on the floor here Link to post Share on other sites
Captain Coffee 2,030 Posted July 1, 2015 Report Share Posted July 1, 2015 there's a good chance you might win a drone I'd like that. Slightly used, half a sortie, only crashed once. Maybe I could start a trophy room. John Taxidronedermy. Amazon is creating unintended jobs to replace the trucker jobs lost. Link to post Share on other sites
allardjd 1,853 Posted July 2, 2015 Report Share Posted July 2, 2015 John what did you eat today? Most anything that didn't eat me first, but don't tell my doctor that. I have only three weaknesses, cheese, ice cream and anything that comes out of a bakery. John Link to post Share on other sites
Andrew Godden 943 Posted July 2, 2015 Report Share Posted July 2, 2015 This implies acceleration is acting on the object continuously. In a vacuum, and independent of the mass of the object, other than from the initial force, without any gravitational force, or any other force acting on the object, it cannot accelerate. Aha - with that stipulated, I agree. Not for the purposes of point scoring, but my original reference to a vacuum was meant to convey "without any gravitational force". However, the energy of any such initial force in a vacuum will eventually dissipate. I can't agree so readily with that one. Mr. Newton covered it in his first law of motion, "Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it." Terminal velocity is reached when speed is constant. In a vacuum, an object will initially accelerate at 32 ft/s2, up to a speed of 32 ft/s, and then remain constant. To your point, "...The velocity will continue to increase without limit at the rate of 32 ft/s2 until it runs out of space to free fall in...", even in the Earth's atmosphere, an object in free fall will ultimately stop accelerating, thus reaching its specific terminal velocity. That's just not the case. 32 ft/s is only about 20+ mph. An object dropped will quickly accelerate above that speed if it has enough distance to fall, unless it has a large area/weight ratio, e.g. a feather. In a vacuum, even that doesn't matter, which Galileo proved. Terminal velocity is entirely a matter of air resistance. In a vacuum, the concept has no meaning. The definition of terminal velocity is: "...the constant speed that a freely falling object eventually reaches when the resistance of the medium through which it is falling prevents further acceleration." I graciously yield on this point (something that certain others don't seem to be capable of doing). My statement relating to physics within a vacuum was incorrect. In essence, the point about a vacuum is erroneously overstated, as my response was to the incorrect statement by MartinW that terminal velocity is 32 ft/s2. In fact, this is actually standard acceleration due to gravity or standard gravity, which is measured in a vacuum near the Earth's surface. I got lost in the moment of the vacuum - probably because it reminded me of what I needed to do around the house. In the atmosphere, near Earth, an object stops accelerating and falls at a constant speed when the air resistance it encounters at its current speed exactly balances the force being exerted by the Earth's gravitation. I got this information about terminal velocity for a human body from a skydiving site... "In stable, belly-to-earth position, terminal velocity is about 200 km/h (120 mph). Stable freefall head down position has a terminal speed of 240–290 km/h (around 150–180 mph). Further minimization of drag by streamlining the body allows for speeds in the vicinity of 480 km/h (300 mph)." Agreed and this supports my original points that the terminal velocity of an object is variable dependent on its mass and the other factors of mass, drag coefficient, and relative surface area. Cheers Andrew 1 Link to post Share on other sites
MartinW 0 Posted July 2, 2015 Report Share Posted July 2, 2015 I graciously yield on this point (something that certain others don't seem to be capable of doing). Who? I've seen plenty of yielding. Me for example when I stupidly didn't engage my brain re terminal velocity. After years of physics posts on everything from M-Theory to the Alcubierre drive... it happens. I blame the heat, 32 degrees here yesterday. Link to post Share on other sites
MartinW 0 Posted July 2, 2015 Report Share Posted July 2, 2015 On the subject of our anti-drone defences. The simplest solutions are the best. A single paintball shot at the lens should do it. With no means to spy on your naked wife through the bathroom window, the drones very purpose is negated. Link to post Share on other sites
MyPC8MyBrain 273 Posted July 2, 2015 Author Report Share Posted July 2, 2015 really Martin, how may marksman do you know of in this forum? and with a paintball gun? common get real; there is no way you can efficiently use a paintball gun to hit the drone let alone its camera lens, now for more important stuff; did someone mentioned pastry? Link to post Share on other sites
MartinW 0 Posted July 2, 2015 Report Share Posted July 2, 2015 I reckon John would be a pretty good shot. Even with a paintball gun. He and Mutley are always at the gun range when Mutley nips over. I'm not too bad myself. Just wait till the offending drone is hovering low, parallel to your bathroom window and it should be an easy shot. Especially if you have a single story dwelling. You could use one of these... Link to post Share on other sites
MyPC8MyBrain 273 Posted July 2, 2015 Author Report Share Posted July 2, 2015 really... they have those now? (i still see a range issue) John and Joe, Hmm... now there's a solution, drone mercenaries for hire John do you have a drone hunting lic? you get to keep the trophy! Link to post Share on other sites
MartinW 0 Posted July 2, 2015 Report Share Posted July 2, 2015 I know we joke, but something occurs to me. A drone was confiscated the other day at Wimbledon. So what if some nefarious individual attached a small explosive device to a drone? Might not be lethal but injury is bad enough, especially if there were multiple drones. Something the size of the Amazon drone can carry 5lbs. 5lbs of high explosive detonated remotely would be pretty nasty. Seems to me we do indeed require the means to down drones. Link to post Share on other sites
Andrew Godden 943 Posted July 2, 2015 Report Share Posted July 2, 2015 really Martin, how may marksman do you know of in this forum?and with a paintball gun? common get real; there is no way you can efficiently use a paintball gun to hit the drone let alone its camera lens,now for more important stuff; did someone mentioned pastry? Well, of course then there's the ones he doesn't know about, because they don't talk about it. I originally quoted the wrong message Chris. Link to post Share on other sites
MyPC8MyBrain 273 Posted July 2, 2015 Author Report Share Posted July 2, 2015 it will not be an easy task by all means unless you govern who gets to get these in the first place; it will be like fighting against a guerrilla army, you don’t know where or when they'd be coming at you, Link to post Share on other sites
MartinW 0 Posted July 2, 2015 Report Share Posted July 2, 2015 In the news today... Prof David Dunn of the University of Birmingham, the incident illustrated a growing problem. He told the BBC that drones posed a danger because their popularity had outstripped both the regulation and education on how to use them safely. http://www.bbc.co.uk/news/technology-33345417 Link to post Share on other sites
Andrew Godden 943 Posted July 2, 2015 Report Share Posted July 2, 2015 Has someone told Henny Penny the sky is falling yet!!! Link to post Share on other sites
MyPC8MyBrain 273 Posted July 2, 2015 Author Report Share Posted July 2, 2015 that’s literally in this case! chicken little was right all along Link to post Share on other sites
allardjd 1,853 Posted July 2, 2015 Report Share Posted July 2, 2015 They could potentially be used destructively. Even a pound of C4 with a layer of shrapnel around it would be pretty nasty. Getting the explosive material would be the hard part, of course. In one of the Dirty Harry movies, a radio controlled car with a command detonated bomb aboard was used to blow up a real car by driving under it and exploding. It's an old idea, now taken 3-dimensional. If anyone ever markets one named "The Martyr" with an extra, unused communications channel built in, it might be a good idea for the feds to have a look at their customer list. John Link to post Share on other sites
MartinW 0 Posted July 2, 2015 Report Share Posted July 2, 2015 Not forgetting incendiary devices of course. A few drones equipped with such devices and remotely guided could be devastating in terms of property damage. Equipped with IR, flown under the cover of darkness and guided toward any location where flammable materials are likely to be accessible, could be very destructive. Link to post Share on other sites
Captain Coffee 2,030 Posted July 2, 2015 Report Share Posted July 2, 2015 Some anti-drone thoughts: EM Arrows: Tip an arrow with a Dual tip, each tip attached to one lead of a very high capacity capacitor, designed to short when the tip punctures the drone it will short the capictor...attach arrow to a fishing line via a "fishing bow" setup. Fire arrow at drone, if it hits it makes an strong EM burst/Electrocutes drone to jam elecronics and knock it out of the sky. Consider recreating your marksmanship employing a Taxidronedermist to make your trophy room more special. Snaggle Arrows: Like above except no capacitors...just a fishing arrow set up with a very sharp and hard tip to puncture a drone...and 6 foot braided steel leader attached to the arrow in case you miss to tangle up the props if you shoot "high". If you Pucture Hit and it keeps flying...fly it like a kite till it runs out of battery juice, then...claim your prize and hang as is on trophy wall. If you Snag it it will crash, claim it and reassemble your prize for display (...perhaps send it to a Taxidronedermist to reassemble it convincingly in a diorama recreating the capture). John's Lawn Darts: (only useful for very low flying drones of course, unless you have a major league pitcher's arm...) Attach tie ropes from one side of a badminton net to each of two lawn darts (...attach other leads to a long fine rope staked to the ground, just in case drone keeps flying and tries to steal your net and darts...). Hurl in front of/over the drone as it is flying over. Claim your prize and hang in trophy room, and of course consider a professional to help with the mounting. The weakest link: Connect several light weight chain pieces at a common center to make a "Chain Shuriken", and hurl it at drones as they fly over, with a bit of "english" to the toss, the chains will spread from rotation of your toss and make a spinning chain barrier to catch props, and crash the drone. Can also be made with light braided steel line connected at center and add small fishing weights to the ends to help the "spread out" effect. Super Soaker Shocker? Not sure how far those Super Soaker water guns will shoot, but if a decent amount, load with very salty water and try to short the drones out. If they can't be shorted out, load with thinned paint and try to blind them. Hope these inspire more. Your's truly, Matt Gardner Taxidronedermy and Diorama Recreations Services Co. (A subsidiary of Death2Drone LLC...anti-surveillance tool supplier). Link to post Share on other sites
allardjd 1,853 Posted July 2, 2015 Report Share Posted July 2, 2015 I think a scuba-diver's spear gun might be useful. The projectile is pretty heavy but is propelled with great force. Using it out of water would certainly increase the range. I believe the spear is tethered, or could be. I do like the idea of the paint ball gun. Some of them are full automatic, though the cyclic rate is very much slower than an automatic firearm - more like a rapidly fired semi-auto. A paint ball is a tough little plastic capsule and has enough mass with the paint that hitting a fan blade might very well break it or dislodge the motor from the mounting, as the shotgun blast did in the video. Hitting the video lens would be pure luck and would do no lasting damage. I very much liked the idea above about using salt-water to short out electronics - great idea. A shotgun would still be my #1 choice but not able to be used everywhere. First one to get five is an ace. Link to post Share on other sites
MartinW 0 Posted July 2, 2015 Report Share Posted July 2, 2015 Hitting the video lens would be pure luck and would do no lasting damage. Except that if it did hit the lens... then the lens would be covered in paint, and the kinky owner of the drone would fail to record your naked holiday guests bottom [Mutley] during his naked sun bathing sessions. Link to post Share on other sites
allardjd 1,853 Posted July 2, 2015 Report Share Posted July 2, 2015 your naked holiday guests bottom [Mutley] during his naked sun bathing sessions. The fevered imagination in your mind's eye is running away with you again. Are your meds expired? Time to get those hot flashes under control. John Link to post Share on other sites
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