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Tethered Spark?
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<blockquote data-quote="Earthman" data-source="post: 90965" data-attributes="member: 16717"><p>Sounds like a crazy application/idea, but...</p><p></p><p>Your tether will have to use wire that is thick enough to have sufficiently low resistance and current carrying capacity to power the drone. Google LiPo batteries for RC fixed-wing and multi-rotor aircraft. The leads on these batteries are short and thick for a reason (hint: lower resistance/heat and higher current capacity). In general, the thinner and lighter the wire, the higher the resistance and voltage drop per foot, and the lower the current carrying capacity. The higher the resistance the hotter the wire gets at a given voltage/current. Finding the right thickness of wire is easy enough if you know the power requirements of the drone and use the right formulas for estimating voltage drop etc. of the wire - basic Physics/electrical engineering.</p><p></p><p>Don’t plan to feed the wire from a multi-layer spool since the layered coils may heat up enough to melt the insulation on the wire.</p><p></p><p>I solved these problems many years ago when I built still and video cameras for inspecting mines thru boreholes, and the bottoms of 100-ft deep caisson foundations. I designed and built an adjustable AC power supply that let me send relatively high AC voltage down a relatively thin wire to the camera(s). I equipped the camera(s) with an onboard step-down power supply to power the electronics. However, my application required much lower current than a drone.</p><p></p><p>The drone’s gyro stabilization system will likely have to do extra work counteracting external forces applied from the wiggling tether. At a minimum, this will draw more current at hover vs. a self-contained battery powered drone. At worse, the drone will crash.</p><p></p><p>You may be able to estimate the lifting capacity of the drone by tethering it with some string to a suitable weight placed on a digital scale and seeing how much the measured weight diminishes at full throttle. Make the string long enough that the drone isn’t in ground effect. Hopefully the drone doesn’t crash trying to counteract the force from the tether. If you know the lifting capacity of the drone and the weight of the wire per foot, you can estimate how much thick, heavy, high-current-capacity wire the drone can lift.</p><p></p><p>Somebody probably makes a suitable drone for this application. Google “indoor inspection drone” and see what you get.</p><p></p><p>Good luck!</p></blockquote><p></p>
[QUOTE="Earthman, post: 90965, member: 16717"] Sounds like a crazy application/idea, but... Your tether will have to use wire that is thick enough to have sufficiently low resistance and current carrying capacity to power the drone. Google LiPo batteries for RC fixed-wing and multi-rotor aircraft. The leads on these batteries are short and thick for a reason (hint: lower resistance/heat and higher current capacity). In general, the thinner and lighter the wire, the higher the resistance and voltage drop per foot, and the lower the current carrying capacity. The higher the resistance the hotter the wire gets at a given voltage/current. Finding the right thickness of wire is easy enough if you know the power requirements of the drone and use the right formulas for estimating voltage drop etc. of the wire - basic Physics/electrical engineering. Don’t plan to feed the wire from a multi-layer spool since the layered coils may heat up enough to melt the insulation on the wire. I solved these problems many years ago when I built still and video cameras for inspecting mines thru boreholes, and the bottoms of 100-ft deep caisson foundations. I designed and built an adjustable AC power supply that let me send relatively high AC voltage down a relatively thin wire to the camera(s). I equipped the camera(s) with an onboard step-down power supply to power the electronics. However, my application required much lower current than a drone. The drone’s gyro stabilization system will likely have to do extra work counteracting external forces applied from the wiggling tether. At a minimum, this will draw more current at hover vs. a self-contained battery powered drone. At worse, the drone will crash. You may be able to estimate the lifting capacity of the drone by tethering it with some string to a suitable weight placed on a digital scale and seeing how much the measured weight diminishes at full throttle. Make the string long enough that the drone isn’t in ground effect. Hopefully the drone doesn’t crash trying to counteract the force from the tether. If you know the lifting capacity of the drone and the weight of the wire per foot, you can estimate how much thick, heavy, high-current-capacity wire the drone can lift. Somebody probably makes a suitable drone for this application. Google “indoor inspection drone” and see what you get. Good luck! [/QUOTE]
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