Israelis build floating electric hover platform Israeli war-tech engineers are planning to build electrically driven hover platforms which would float like balloons tethered to ground- or vehicle-mounted energy sources by long power cables. The Electric Tethered Observation Platform (ETOP). Credit: IAI Uh-oh! Power cut! Flight International reports that the machines …
To reduce the weigth of the tether, which is mostly the conductor metal, the only thing needed to do is reduce the conductor diameter.
To cope with the increased wire resistance, there are 2 alternatives ( non excluding)
1 - Use a better conductor ( gold ) or a superconductor (just find one that works at room temperatures)
2 - Increase the line voltage, as to reduce the intesnsity to carry the same power. Of course the isolation will have to be enhaced, but plasitc is a lot less dense, even more if is filled with vacuum bubbles.
Copper is both less dense and a better electrical conductor than gold, so they're probably already there. For longer tethers is might be possible to use aluminium conductors: long-distance overhead power transmission lines are usually aluminium because of the low specific density, despite the losses incurred by being a poor (relative to copper) conductor - if they were copper the pylons would have to be about 10m apart to support the wires.
Anyway, given that pikeys are prepared to risk life and limb to steal copper, I don't think the gold tether would last very long!
If they could increase the carrying capacity to one or maybe two humans, this could have enormous potential for the emergency services for rescuing people from burning buildings and rivers, etc.
Not all technology advancements need to center around the destruction of worthless fleshings.
Ever try using a helicopter in a city or other area with a lot of trees? Rotors tend to have issues when they hit the sides of buildings.
Limited it may be but this could still have lots of uses in search and rescue/disaster relief. Pity it's use wont be limited to humanitarian endeavors.
a form of electric barrage balloon?
I've not read of an air force based in Gaza, bit the idea has potential.
It could be used by the French as a quick pop-up solution to stop all those helicopter based gaol breaks if there were enought of them housed on the perimeter walls and internal buildings.
Icon as that's what the pilots might think. Loosely
At 100 metres up, a burst from an AK47 is VERY unlikely to hit the target. A single, well aimed shot from someone who knows what they are doing has a chance, but only a slim chance. And being within 100 metres of the base-station is unlikely to be good for the health of anyone that wants to try it.
- smaller and thus less visible and less easy to damage under enemy fire.
- being able to control where it is located, it can remain in a single spot rather then being at the mercy of the wind (even a tethered balloon will hang downwind as far as possible from the tether location)
- the gases in a balloon are expensive and will eventually evaporate or escape from the balloon, thus they still need to be taken down and refilled occasionally, this has the potential (if run off grid) to never need to be brought down and to be "cheap" to run.
shall i go on?
Looks remarkably like the device used by Gene Simmons to evade capture in the old Michale Crichton/Tom Selleck movie.
The other reference is a JWR Taylor book of the early 70s. Tethered surveillance platform with fuel hose/tether for virtually unlimited endurance. Developed IIRC by Dornier and called something like "Peewit".
Looks like someone went to the local model shop, bought a few ducted fans and solid state gyroes off the shelf and glued them together with a microcontroller. I'm sure it's cool to watch, but hardly groundbreaking (unless the power suddenly cuts, perhaps).
You could probably shove something like this together yourself for a few hundred quid.
A short course in electrical energy would benefit many respondents. Here are some highlights:
Conductors: Fact: Gold is a better conductor than copper. We do not use it because it is bloody expensive, you might find it plated onto copper in Hi-Fi wiring because high frequencies do not pass well through the interior of metals (all to do with self inductance). Aluminium is not as good as copper and larger sizes have to be used for the same volt drop. The conductor weight is less because of the lower density but the overall cable weight is much the same because of the grater insulation weight, aluminium cable is stiffer as well.
High frequency generators and motors are much smaller and lighter, 400Hz is used in aircraft for that reason. There is not much influence on cable size unless the frequency gets too high, see above.
Power system: use three phase, you get a lot more power for the volt drop.
Volt drop: for safety the voltage at the bottom end has to be limited, in the UK it would be 110V. You might be able to use more elsewhere or in military applications, but there is always a limit. If you need so much power for the drive motor this will fix the current but the cable volt drop is proportional to the square of current, so more power needs larger cable and larger cable needs more power. Catch 22, Ha Ha!
Why bother with electricity, it might be quieter but the fans still make a noise? I am sure a suitably silenced motor can be found and if the device is tethered it does not need to carry the fuel, that can be fed from the ground through a umbilical which would be much lighter and more flexible than a cable.
But wait a minute, why use lifting fans at all? Dynamic lifting devices would also work and if payload is an issue you do not even need motors in the device, they can work by induction powered by compressed air fed through the universal umbilical.
See solved it. What you looking at me for? I like it in here. Please not the little pink room again.
No, gold is not a significantly better conductor than pure copper. It is a better conductor than tarnished copper, which is why it is used for exposed contacts that would end up corroded if they were made from copper. (Gold also has a lower contact resistance, as it is softer, but that isn't really relevant to the original point.)
Since this is intended to be a military vehicle I really don't think they care about safety all that much, besides if 240v is safe enough for the amateur electrician, I don't see why it would be limited to 110v outdoors, other than for compatibility with existing kit, and British army uses 6v, 12v, 24v, 110v, 240v and if I remember correctly there is a fair bit of three phase, 415v where it is needed.
http://www.thinkgeek.com/geektoys/rc/79c7/
Silver is the best conductor (unless anyone knows differently, or a room temp superconductor that won't snap like a dry twig?) but oxidizes rapidly, maybe a coating of gold and an aramid thread to stop it stretching. Part of the payload can be a small battery so it does not crash to earth, or deploys a foil or parachute when the power goes.
As to arming it... Meh.
IAI filed an international application for that thing 4 years ago but did not pursue it further, possibly after seeing the quantity of prior art cited by the patent office.
https://register.epoline.org/espacenet/application?number=EP07736433&tab=main
http://v3.espacenet.com/allCitations?DB=EPODOC&locale=en_EP&FT=D&CC=WO&NR=2007141795A1&KC=A1
A 100m elevation is quoted, but I guess that the achievable height is a compromise between the amount of tether paid out and the global weight. A 20kg payload seems quite a lot though, considering the thrust provided by my domestic fan.
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