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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  • Varga, no need to apologize for showing milspec gear. We have civilization available to us because rough men and women stand ready to stand between us and those who would do us harm - updating George Orwell.
  • http://solarworld.com/SolarMini-Panels%26Motors.htm $96 + frt gets me six of the 4-3.0-100 panels.. three in parallel, then two triplets in series gets me 200ma at 9v in 56 square inches of wing surface, or raw DC voltage suitable for 20% duty cycle on a one watt repeater. Without urban chatter competing to drive up the background floor, very reasonable power for the repeater and its controller. East of the Cascades, sunshine is plentiful... although fire soot on the cells will be a problem.
  • Moderator
    This month's copy of Fly RC has an article about Bob Davis (of Davis Diesels) who has long worked with the military of UAV powerpalnts and is quoted on the ability of a diesel RC engine to fly for 24 hrs on one gallon of fuel AND turn an alternator for on-board power for the telemetry and video downlink.
  • http://www.rcgroups.com/forums/showthread.php?t=451334 shows it's eminently practical to design and this thread http://diydrones.com/forum/topics/705844:Topic:38565?x=1&id=705... emphasizes <400' and within LOS which is just dandy... so now it's time to start working on the radio repeater side, and putting the antenna in the wings (I think)
  • Sorry for showing military content, the main point is their design an their specification.
  • @john, from the proposed utilization I would say single motor 4 stroke fixed wing airplane, with 2-2.5m wingspan, but a glider hybrid with gliderlike wings but more like a trainer body, this would give tons of lift, and therefore minimize fuel consumption.
    A plane that size can easily keep quite some payload up in the air for a long time if you have a large fueltank.
    That could then be programmed to circle an area at a set altitude until fuel is low, and then return to base or be flown manually back. Would need some filtering on the intake air to remove the carbon etc if it flies over a forest fire or similar.
    It could also of course be fitted with a camera pod with steerable IR thermometer or other similar sensors which could turn out useful.
    I believe the main issue for something like this would be the support personnel and service to the vehicle. It would have to be very sturdy and field friendly which is generally something hard to put together as a one-off or without a design team and industrial manufacturing processes - at least in a user friendly way
  • Tethered aerostats are used as relay stations:
  • Hey John....If you can, send me a little write up of your idea. I think I might be able to help you out a bit. I'm a cartrography and GIS major. I was also in the Massachusetts Emergency Management for a while. I'm doing my Senior Thesis on drones and building one for Cartography and Remote Sensing purposes, but I think I can build a system that can do what you want too. jwraymond@gmail.com
  • Keeping an amateur repeater under 400' AGL would be dandy for our needs, so AFAIK from what I read here, no need for autonomous operation as there must be a ham in the field logging the radio traffic anyway, but the $30 autopilot DIY kits I read here allow that ham to be distracted, handle relay traffic, go on bio-breaks, etc.
  • Moderator
    We have had a member who was making a presentation for a fire rescue proposal last year, but the concensuos was that the greatest hurdle was with FAA approval.
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