I can tell you that there is no exact science to what a craft will do when a lipo becomes dangerously low. You will not see the craft drop out of the sky like a stone due to a drained lipo. You will see it do exactly what happened in the video...not enough juice to sustain lift and level flight but just enough juice to keep the props spinning while causing an uncontrolled b-line to the earth. Over the years of flying I've personally had copters power dive to the ground (due to low battery power) with motors spinning. A complete power failure will cause the copter to drop out of the sky like a rock which was not the case in the video. The owner confirmed that the lipo died while in flight. My theory, either dead lipo or GPS issue.
maybe was just one of the two batteries if they use them separately; one side of the copter shuts down, the other one keeps spinning...
I've had two instances of low battery when I first started flying my hex. Both instances were at low altitude and the speed controllers did exactly what they should have done. They reduced power to the motors and the bird just started sinking slowly, but level the whole time until I landed. Fortunately, it was just when hovering very low. In the early days of the Hoverfly Pro boards there were instances of flipping when you switched to altitude hold, it would just roll right over. They fixed that issue with firmware upgrades and I haven't heard of it lately. My point is that this whole industry is pretty young and there are a lot unknowns about what can wrong when using control boards that take thousands of lines of computer code to make work. We are all basically field testing all these companies products at this point in the products timeline. When you start adding GPS, RTH, auto land, etc. etc. it gets even more complicated. Does anyone know if the voltage cutoff can be raised on the Turnigy Plush ESC past the generic "High" setting. Seems like they should make an ESC specifically for multi-rotors that would allow you to set the voltage at maybe 3.5 volts instead of around 3.0 volts, for a bit more cushion. I suppose you can use alarms, but I'm not sure you would have been able to hear it with the crowds at the bull run.
Thanks for that information, Howard. Do you happen to recall where you saw this explanation, please? Thanks Andy.
FWIW, the MK boards allow you to set the alarm threshold, the Graupner HoTT system allows the transmitter to speak the battery voltage and the Smart On Screen Display also shows it superimposed on the FPV video. And the Navigation Control Board writes a flight log so you can build an historical record of specific batteries (if you care to log which batteries you're using for given flights). Andy.
http://wtvr.com/2013/08/26/great-bull-run-crash-victims/ “The reason that was given to us was that the UAV or the drone, the battery had died, and it basically plummeted because of that,” Fillius said. CBS 6 spoke by phone Monday night to Scott Hansen of Virginia Beach. Hansen claimed to own the remote-controlled aircraft involved in the incident. Hansen, who directs and produces films, also leases specialized camera equipment, including his remote-controlled aircraft camera worth about $7,500. [CBS 6 EXCLUSIVE: FAA investigates Bull Run ‘drone crash’]"
This whole episode stinks....everything about it. I would lay odds that nobody involved in this is telling the truth.
The crash is unfortunate and it will bring more scruntity however it was bound to happen sooner or later. There's nothing anyone can do about it. Hopefully this will be a lesson learned for all us the next time we get the urge to do something that our gut is telling us not to do. Sometimes our desire to get a great shot overrides common sense. A lot of copter pilots overlook risk management or ignore the risk management red flags. With the amount of multirotors out there it was only a matter of time.
The turnigys just get set to Nimh which effectively disables any shutdown when using lipos. I wouldn't fly anything without having telemetry sending voltage directly to me in real time. I find it difficult to understand how someone could have a crash due to low a low battery. It's at the top of the list of items needed to stay in the air and should be treated as such by everyone. I'd much rather have someone angry at me for landing during a shot, than to have to explain why I flew in an unsafe manner.
I have seen a lot of guys who run one battery post about battery related accidents. If you don't keep data on batteries from the time you get them its harder to determine their health. There are some things you can do to check a battery like discharge it to 3.5/cell and see what the voltage difference is for each cell. You can also discharge a completely full battery and see how much power it discharges. Most people don't have the time or energy to do that much. For me I have 10 pairs of batteries so its not feasible to do very often. For a battery that's at the end of its life for example, if you run a battery like unknowing its poor state, the voltage maybe 15.5 after 20 seconds but then just go to 13.4 on a dime. Or you can have a situation where the battery voltage is in the normal range, but if have to do an abrupt manuver, the current spikes to 150 amps plus and there's not enough reserve in the battery. This is why you see most people fly with 2 batteries in applications where its practical. I know some people on the board have the mind set that running two batteries at the same time doubles your chances of having a bad battery but I truly believe in the extra reserve of the 2nd battery giving you enough reserve to make a emergency landing. If I"m flying any where in public with a gimbal on it I run 2 batteries.
I completely understand what the factors are leading up to a crash from a low battery. I just meant that pilots have a responsibility to know the health and state of their batteries at all times. Procedures should be in place by each pilot to ensure they are operating within the ability of their equipment. The article blames a low battery for the cause of the crash, but it was a failure of the pilot to operate within the capabilities of the aircraft. The blame is solely on the pilot and he should accept that and not try to blame the equipment. The equipment functioned exactly how it was supposed to.
For me its the action of the individuals involved after the fact that is most disturbing. Its how you act under pressure that is most telling of your character... big fail here. Face it, falling out of the sky or flying away is going to happen to all of us, if not multiple times. If you think it wont then you are kidding yourself. The only thing you have a tiny bit of control over is where it might go, and the thing you are in complete control over is how you respond afterwords.
It was definitely disturbing to see the rig being passed down through the stands and only bystanders checking on the injured. I could understand rushing to kill the power to the rig first so as not to cause any more possible damage, but that only takes a split second.
Ya true too... Although i was more refering to attempts to cover up tracks by deleting photos, like they were never in the business. Just too sneaky for me.
And then there is the Wayback Machine at archive.org. If it has had a chance to crawl/spider the web site (that is, pass over it a make copies), then it doesn't matter if they have deleted images -- you'll still be able to find the web page as it was. Just as a demonstration, here's what my web site looked like on December 22, 1996: http://web.archive.org/web/19961222024909/http://jli.com/ Andy.
Thanks Andy for that website (web.archive.org) fun looking back at our first attempts as compared to today
These guys are all full of it. "Hansen said he leased the unmanned aircraft to the organizers of the Great Bull Run. He said no training is required to fly them, but he only loans the device out to pilots with at least a few weeks training." WTF?