I'm an amateur radio operator (K7AAY) specializing in emergency services work, seeking a way to loft a repeater for fire fighting support and other emergency services work. We get wildfires and the state rado net has big gaps in canyons and the boonies.Any design would compete with current state of the art, i.e., a weather balloon, a tank of helium and the tether with a wire carrying 500ma at DC voltage adequate to deliver 8.4VDC to the transceiver (an HT or Handheld Transceiver and a controller board) on the weather balloon.How much mass can I squeeze into a UAV?What's the optimum design?1) Solar cells on fabric to also run an electric motor for sterage on a lighter-than-air craft2) a larger LTA burning hydrogen from the envelope to run a motor with a small generator set as well as an engine for steerage, or3) a multi-engine heavier-than-air craft with larger than ususal fuel capacity?
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  • btw, i apologize if i'm just "not getting it" i'm begging someone to explain it to me.
  • also, i, if you want to make it more advanced, I think you can add a processor to it, allowing it control to an engine on there to keep it in a stable position, or reposition it if necessary. Obviously the processor would have controls to the tether to increase or reduce rope length. Heck you can add a nice little "fail safe" feature that it can disconnect from the tether, if it cannot be reached and the fire is at had, and then floats/flies off until it reaches a untouched area for retrieval. That itself shouldn't be too hard to do.
  • i'm not sure why one would need to scan, i guess is what I'm saying. as a repeater, you probably have to have line of sight with the horizon with all the nodes, right? what can a plane do at 400ft that a ballon cannot? I am curious :).

    Honestly, a really nice method, if this hasn't been thought of before, would be to drop an array of ballons, over an area that is known to have no signal, tethered to the ground and have them repeat the signals, like ad-hoc wireless, allowing you to have maximum coverage AND versatility.
  • Genesis,
    except I think a balloon is the current state of the art. He was looking for improvement.
    I tend to agree, mobility is better for scanning.

    A balloon could be a flight hazard, and it could be argued that a uav can be more quickly deployed.
  • basically what i mean, since i can't edit my post, is KISS

    KEEP IT SIMPLE STUPID!!!! :)

    but really, make it deployable faster than that thing...there's nothing like a big white ballon in the sky with a string on it to give away your position.
  • It think varga has a point here...but not in the way that he may have meant it.

    You don't need a UAV for this at all. It would be a waste of a good robot. You need a ballon on a string. Here is why:

    You are just covering gaps in communication.
    fewer FAA hurdles, ESP if you put a blinking LED on the top of the ballon
    No fuel to think about
    Less weight concerns.
    Stationary so you wouldn't have to worry about any circualr position or anything.

    and if wind is tough and you really want to make sure that it can handle the weather, you can add a prop and fins to it...and STILL keep the battery pack on the ground!

    Just make sure that it has a quick retrieval system and task a couple fire men to get it back incase the blaze hit the UAV's area, but those firemen would be tasked with making sure that the battery on the ground still held a charge

    Shoot...now i want to make it and sell it...
  • aiming at something small cheaper and without a COS to demo proof-of-concept, then we worry about involving The Powers That Be for a COS and a bigger bird. Plenty of opportunities for using a 400' AGL bird in the work we do.
  • It sounds like what you want is a UAV as a high-bird. In the type of terrain you're talking about, I don't think 400'AGL would be enough. You should think more along the lines of 4,000-6,000'AGL. In a wild fire situation, there should already be a TFR over the area to allow fire helicopters and tanker aircraft to operate in the area without having to worry about news helicopters or pilots rubbernecking. You probably need to keep your UAV above the other aircraft operating in the area.

    The other advantage of being at the higher altitude is that you'll be able to cover a wider area. The downside to this is that a handheld won't be nearly powerful enough. All of a sudden you're probably talking about something more akin to a mountain-top repeater, which would weigh a lot more and take quite a bit more power.

    I think your best bet is to get plugged into the air branch of any local incident command center. I bet your local RACES group has some in-roads there.

    This sounds like a great use of this technology to me, but it also sounds like a huge undertaking. Good luck.
  • @john: I would not go solar if I was you, they are heavy and ineficcient for anything other than research aircraft. I would use 4 stroke or indeed diesel as Sgt Ric suggested and driving an alternator off it to power everything.
    Solar would also not work well if you have smoke blocking the sun or bad weather.
  • Sgt Ric: Which issue? http://www.flyrc.com/toc_03_09.shtml does not see that in March 2009...
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