BAN ALL DRONES! - Eric Zorn, Chicago Tribune

Discussion in 'Hangar Flying' started by Inverted Vantage, Aug 1, 2015.

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  1. Dec 19, 2015 #421

    Hot Wings

    Hot Wings

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    Don't know how many watts the current systems use or how little power they might be able to get by with using good design - that the scale of the drone market might be able to afford. There also might be the option of not requiring the same range for low speed/low range drones, or maybe use some kind of hybrid system where the low and slow guys use FLARM, or similar that gets passed along to the ADS-B fleet if one is close to the FLARM equipped unit?

    Is the transmit power consumption really that much of a problem for gliders? Just a wild guess at some numbers:
    5 watts transmit power for 1/10 second each one second interrogation/transmit cycle @ 50% efficiency = 10 watts.
    At 12 volts that = .83 amps.
    An 8 hour flight would use .8 hours of transmit time.
    For .8 hours @ .83 amps = ~1 amp hour.
     
  2. Dec 20, 2015 #422

    D Hillberg

    D Hillberg

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    B.S, target conflicts and an overloaded system not to mention the added costs and useless weight.
     
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  3. Dec 20, 2015 #423

    RPM314

    RPM314

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    Are you suggesting this as a means of training US civilians to be good drone operators? That's like using Essex class carriers as a training for jet skis.
    The 'easy to fly' option that is drawing in all the clueless folks who need the training are multicopters, which is a completely different type of flying for one thing. But the main thing is that military operations are about...well if I knew they'd probably kill me. But civilian training needs to be about coexisting with other aircraft and making good safety decisions. Derping around at FL10 with a Predator through a spotty satellite connection isn't gonna do that.
     
  4. Dec 20, 2015 #424

    blane.c

    blane.c

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    Predators for professionals, I'm talking about little spy drones, sneaky little bastards much smaller than a predator for the amateurs.
     
  5. Dec 20, 2015 #425

    gtae07

    gtae07

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    So it looks like UAS registrations will be public after all :devious:

    Forbes Welcome
     
  6. Dec 20, 2015 #426

    Topaz

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    Sorry, going with Hillberg on this one. I think that power consumption estimate is wildly optimistic.
     
  7. Dec 20, 2015 #427

    Hot Wings

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    Yup, very optimistic - in one sense. But after a bit of searching:

    Per AC 20-165 transmit power is between 21dBW to 27 dBW. 27dBW works out to about 500 watts. At 12 volts that is ~40 amps. BUT I was also way off on the transmit time. Each data packet sent per interrogation is only 120 microseconds. So it seems that power levels could still be reasonable enough for small drones to handle.

    Doing things the simple way and just looking up some real world numbers - the Dynon SV-XPNDR-261 consumes .15 amps at idle and .34 active at 14V. That is less than 3 amp hours for an 8 hour flight. Even factoring in the limits of a Lipo battery the typical 5000mAh 3S pack is going to be plenty of power. For a drone with a flight time of 30 minutes another .20 amp hour or so of battery seems to me to be quite reasonable. The added weight? Not so much.

    Mode C transmits a 24 bit message once per second. 1090ES transmits it's 56 bit position message 2 times per second for airborne units. I presume this means that the full 112 bits are also sent since they contain aircraft ID, parity check and such.

    I found one number, recorded near Frankfort Germany in 2001, of 33K replies per second and alleged to represent one of the most aviation dense places in the world. This leaves several orders of magnitude of data space to add capacity to the system.

    1090ES airborne transmit range is around 150 nautical miles - line of sight (170 statute miles). We don't need to see all of the targets in this area, just the ones that are likely to come close to us. If the targets shown to the pilot were limited to only those within, to guess at a number, 10 minutes range that limits the radius needed to display to only 50 miles due to the speed limit under 10,000feet. Letting the computer filter out targets that would need more than a 10G acceleration to cause problems further reduces the number of targets displayed to the pilot.

    So why not make the drone guys use ADS-b and let us reap the cheap prices for hardware from their added volume? We are stuck with the ADS-b mandate. Let us spread the pain around to any drone that can fly further than XXX feet from it's pilot or weighs more than YYY pounds.
     
  8. Dec 20, 2015 #428

    BJC

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    How would that work?

    On a local VFR flight, would I need to monitor an ADS-B IN display for traffic that would be almost impossible to make visual contact with? Would the RC / 'copter operator be required to monitor, detect my aircraft, and comply with the right-of-way rules of flight? Would the RC / 'copter operators need to be trained and licensed? Would either of us be required to communicate with ATC?

    What minimum altitude do you propose for the system? Ground to air and air to ground ADS-B is line-of-sight, and ground to ground takes a very reliable communication channel. How many new ground stations would be needed? Computers? Controllers? Additional WAAS stations? Who would pay for the required system additions?

    Thanks in advance for taking the time to explain the details of your proposed solution.


    BJC
     
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  9. Dec 20, 2015 #429

    Himat

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    Really?

    Looking at the spec sheet, https://www.aircraftspruce.com/pages/av/adsb/transponder11-12038.php I fine 0,45A current draw at 14V and a unit weight of 1,35 kg. Four A123 cells should provide power for around four hours of operation. Cell weight is 76 grams, a battery pack would be 304 grams plus cabling. To get ADS-B for four hours would then weight your down about two kilograms with cabling and antennas.

    If the architecture of the ADS-B is suitable for use by a large number of very diverse vehicles with very different operation modes is another question. A quick search on the internet provided some papers that show that the ADS-B system have some weak sides.

    A side note, peak transmit power is 240W in the ADS-B. Either is this a really long range system or it is grossly inefficient. The GSM cell phone system get away with 0,5W peak transmit power. The old NMT cell phone system in Norway used to have a 4W peak transmit power and a over the hills and far away range.
     
  10. Dec 20, 2015 #430

    RPM314

    RPM314

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    What aircraft model is this? Does it actually exist (yet)?
    Further, how do you expect the military to agree to start this program up when not caring is a perfectly viable option, and drone operators to shell out for it when flight sims and local clubs are much cheaper and relevant training?
     
  11. Dec 22, 2015 #431

    DangerZone

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    I don't know how much you guys watch skiing, but a drone almost hit Marcel Hirscher... He's a great Austrian skier and was very lucky to evade the hit.

     
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  12. Dec 23, 2015 #432

    Inverted Vantage

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    This is why the way the FAA is approaching drone regulation is kinda stupid in my opinion, because all it does is look at how to punish people, BEFORE it looks at how to educate them. The current FAA drone regulation requirement is shortsighted and blame-focused, because there isn't even a knowledge test! "All" they want is your name and your numbers.
     
  13. Dec 23, 2015 #433

    Doggzilla

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    Honestly, people need to be more excited about educating themselves. I dont see why so many people have to be educated when so many other people WANT to learn. But of course, we have to make money off of them while they do! Cant let people be learning without making money off of them! How else would we learn anything if we didnt have to spent money on it? /s
     
  14. Dec 23, 2015 #434

    DangerZone

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    I'm surprised there is no protection method for a safe landing in case of battery power loss. Such drones could be saved with a light and inexpensive miniature parachute or airbelt which would both protect the drone and the people on the ground. I proposed a couple of cheap&efficient ideas/systems some five years ago but there was simply no market demand at the time. Maybe the newest regulations might allow this market to develop for heavier and larger drones.
     
  15. Dec 23, 2015 #435

    Doggzilla

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    Parachutes take a bit to deploy and need to be fairly large. An airbag would actually fit this kind of thing much better. They just use little chemical charges to inflate the airbag. Setting off either a parachute or an airbag is another matter.
     
  16. Dec 23, 2015 #436

    RPM314

    RPM314

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    I've never seen it to be much of an issue. Batteries don't "run out" of power, the voltage just decreases until the copter hits the LVC (which is bad for the battery but not fatal). Even if it's on fire you can still pull current out of it. Quite different than engine outs with 2 strokes.
    Not saying it can't happen, it's just not a likely failure mode.
     
  17. Dec 23, 2015 #437

    bmcj

    bmcj

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    What about three orthogonally mounted large flexible rings that surround the drone in a protective flex cage? No need for recognition and deployment action since it is always in place.
     
  18. Dec 23, 2015 #438

    skier

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    Battery loss as pointed out would be quite a rare event. However, the AR Drone will land itself if it gets out of range or the battery gets to a point deemed to low. I assumed all higher end quadcopters had such a feature built-in. Apparently that isn't the case.
     
  19. Dec 23, 2015 #439

    nerobro

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    LiPo batteries can, more or less, just shut off. Take a look at the voltage curve on a LiPo and you'll see it falls off a cliff, and a tthe same time, the internal resistance goes up. It quickly gets to be un flyable. But.. I believe that is not what happened here.

    To quote myself on another forum...

    That multicopter was not likely commercial, and if it was, it wasn't using custom flight software. I think this ends up being a bad operator setting up the failsafes wrong, and having something go wrong with signaling.
     
  20. Dec 23, 2015 #440

    RPM314

    RPM314

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    That's why LVC is a standard feature on even the most basic multi ESCs and FCBs.
     

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