If anybody is tired of seeing these posts, let me know. I don't like the "no news is good news" maxim, so I thought it'd be helpful for folks to see what good flights look like. It's certainly worthwhile to learn from crashes and other problems, but I don't want members on this forum to think it's all bad news. A properly built (thank you Andy!!!) copter that's well-maintained and carefully balanced will yield excellent results.I was asked to photograph a nearby house that's for sale. It's in a very nice community with a golf course, a Ritz Carlton and the Pacific Ocean all nearby. I went over this morning with my Cinestar 8 (mostly stock with MK stack) with 2-axis gimbal with Radians, and my 5D Mark III with Canon 24/2.8IS lens. I flew two short flights (6 minutes or so) from the front and rear of the house. Flew purely LOS at about 65-85 meters AGL. The data in the GPX file is very encouraging, as my efforts to properly balance the copter have yielded the best, most balanced numbers I've seen yet. I'm flying with dual 8000 mAh Zippy batteries on these flights. I swapped batteries after the first flight (I never like to take off on batteries near 1/2 their capacity). I only shot still photos at this house, using a cheapie (eBay) intervalometer set to trigger the 5DM3 every 3 seconds. The camera was set to autofocus and manual exposure using 1/500 at f5.6. I left the ISO on AUTO, as I've found that to be the best way to do stills. The resulting exposures ended up spanning ISO 250 to 640. Here are a few photos, as well as the GPX files. And I've also included the summary of one of them. MK Version: FC HW:2.1 SW:0.88n + NC HW:2.0 SW:0.28o Flight date: 5/14/2013 8:45:57 AM Flight time: 8:45:57 AM - 8:51:25 AM (328 secs, 00:05:28) Batt. time : 328 secs, 00:05:28 Elevation(GPS) : 1.165 38.15 85.532 m (min/avg/max) Altitude(Barom.): -1.65 37.85 87.65 m Vertical speed : -3.91 -0.06 2.58 m/s Max speed : 23.8 km/h Max target dist.: 0 m Sats : 9 10 11 Voltage : min. 14.7, max. 16 V Current : 0.5 69 95.9 A Wattage : 8 1065 1409.73 W Capacity: 6347 mAh Motor1: 3.1 9.8 12.6 A Temp: 12 61 76 °C Motor2: 4.6 8.9 12.9 A Temp: 13 65 82 °C Motor3: 4.5 9.5 12.6 A Temp: 18 66 81 °C Motor4: 3.8 7.7 11.1 A Temp: 17 60 75 °C Motor5: 3.7 9.1 12.6 A Temp: 16 59 82 °C Motor6: 2.2 6.7 10.5 A Temp: 21 52 71 °C Motor7: 1.5 8.6 12.0 A Temp: 17 50 64 °C Motor8: 0.9 7.0 10.2 A Temp: 18 49 63 °C Magnet Field: 93 95 103 % (ok) Magnet Inclination: 53 59 69 deg No errors found
You should try using the Magic Lantern firmware for the 5D. You can make the camera work as an intervalometer all by itself .. no need for the ebay one. It'll save you the tangles and weight. I agree with the 3 second shooting though. It makes more sense to just take a shot ever 2 or 3 seconds than worry about having to pull a trigger button and be unsure if you got the shot or not.
Superb images! I have the same setup, but I am using a single 8amp lipo (QC). You recommend using two 8 amps?
Thanks! I believe in dual batteries, despite the assertion that (strictly mathematically speaking) this increases the probability of failure. I'm the pilot, and on my ship, that's the rule of law.
Yes, it doubles the chance of failure of a battery but greatly, greatly reduces the effects if a battery goes bad in the air.
Well, we really don't yet know how a battery fails in flight, Tyler -- if the voltage on one (bad) LiPo sags, it's going to look like a load resistor strapped across the good battery and will drag the good battery's voltage down too. The good news is that batteries and copters (as well as other aircraft) don't actually know the math of probabilities...so shhhh....don't tell'em. Andy.
Steve, can you tell me which connectors you are using to get the live video out into your down link? I think what I need is first this cable : Canon 5D Mark III -> AV Cable male (RCA plug) then this adapter : RCA female -> RCA female adapter when THEN finally plugs into the male RCA video downlink. Does that look right?
I have been thinking about this recently . I suppose two batteries may at least may make the batteries more stable since the two batteries are sharing the load. Although, the double edge sword is when you fly cameras like an FS-100 with 18-200 glass the copter is at max gross weight IMO. I am going to try it when I get some new batteries.
Shaun, there must be an engineering or scientific term for something that makes good situations better and bad situations worse? Kind of like alcohol, I guess.
Is there any way to fly with two batteries? have them setup that if one fails the other one kicks in? i dont care about the xtra weight if it means I have back-up power
If you are dragging two batteries in the air, you may as well make use of them both. What could be better is a cut off switch, so that if a battery voltage drops below it's proper cell voltage it will be cut off from the circuit. The danger is of course both batteries being cut out by error
Shaun and I have been discussing that off-forum. You can't use a diode because of the voltage drop across it when it's operating with normal batteries, and it would have to handle 100A. So the best would be some kind of solid state relay, I suspect, but the 100A ones are quite large. And, as you say, then you add in the risk of the fail-safe failing! Andy.
I believe we referred to it as a conundrum. I have two problems to solve X and Y. I solve X but I made Y worse, the goal is to try to meet it somewhere in the middle.
I found that they are about a pound or more a piece for an industrial grade relay that can handle 200A a per relay. I am now brewing up another idea and putting in some research into its feasibility.
Not a bad idea Andy and I have pondered it a bit. However, there is an issue when knowing how much current is going to the bad battery. If one battery starts shorting than that is when the current is going to follow the path of least resistance and start feeding the bad battery. The question is, how much of that short is conductive versus resistant. Will there be enough of a current spike to trigger the fuse in time. If it is too slow it may brown out the copter and shut the systems off in flight. Secondly, at what current do we consider safe so we do not put too low of a fuse in and causes a fuse to prematurely blow which could trigger the second battery to spike and shut that one off line as well. An ideal situation would be to actively monitor both batteries through the balance plugs via a small micro controller. Through comparative logic you would set a level that you would trigger a relay, to open the circuit of the bad battery. Its a complicated problem I am afraid.
I guess you would need to allow enough current for a single battery to power the whole copter if a fuse did blow on the other.
The difficult part of this problem is that we don't fully understand the nature of the (potential) failure. Do we have empirical evidence that this particular problem (battery 1 fails, and "drags down" battery 2) has actually caused a catastrophic power issue on somebody's copter? It seems most crashes (maybe all the ones of which I am aware) have been the result of some other type of failure (mostly electronics such as radios or flight controllers). Or pilot error. With all due respect, Shaun and Andy, I'd rather you guys think about a way to run an independent, backup flight control system capable of at least landing the copter in an emergency. In other words, something with just enough "smarts" to get the copter on the ground without any link to/from the ground. Basic GPS, etc. The low-voltage connections amongst the flight control systems would be far easier and cheaper to switch. And a watchdog system that could make the decision to take over the copter would be easier to engineer than a battery watchdog. What do you think of that? Oh, and with respect to pilot error, having a hot spare of one of those could be helpful in some situations, too.