Flying two quadcopters at one time. Never again! LOL

Long Range RC

Long Range RC

Well-Known Member
Today I flew two H4 Hornet quadcopters at one time to try and get a cool aerial video. Way to stressful and I don't think I will do it again.

 
How did you fly both at once? Did you have one set up with GPS waypoints and then followed with the other - or was someone else flying the second one? I can see why it would be stressful! It's a very cool video though... especially when you're flying close by the other copter.
 
I put one up and locked it in GPS hold and then set down the controller. I picked up the other and launched the second quad. On my way up with the second quad my daughter yelled, "Dad! Your other chopper is drifting." I had to reach down and fly the first one with my left hand, two fingers as I controlled collective on the second with my right hand. I was able to reengage the GPS lock on the first quad and quickly landed the second one and then back to the first. LOL. Almost lost one for this stupid shot......

I think in the video you can see me push the first quad forward and away from the second one as I was flying it up. As I am landing the quad in this video you can see the other controller sitting on the ground next to my knee.
 
I am not sure, I never had it happen before. The cloud cover wasn't bad so it couldn't have been the GPS signals. I didn't think to check the weather report for the other cause of GPS interference, The NASTY SOLAR FLARES. Some people don't even have clue that a good solar storm can send your multi-rotor into and uncontrollable fly off if your are flying in GPS mode. If you do ever start to have a non responsive flyer and you are flying in GPS mode a quick switch to manual or straight atti-mode can bring it back into control if your radio signal is still being picked up but your receiver. Try to keep this in your brain housing group for the time you might need it.
 
Yes I think GPS is great, but we may rely on it too exclusively. I may allocate one of my six APM modes to MANUAL in response to this, and other reports I've seen in YouTube videos and on forums. It would be interesting to know what logical sequences the controller boards use to make flight decisions, and how such decisions are made in the event of conflicting indications from gyro compass and GPS. One of the three is probably being given more weight than the other two, and I'd guess it's GPS!

I wonder if the telemetry on an APM controller that returns to base and gets recorded includes streaming readings from all the sensors (or if it could be made to)? That's probably a question for the DIYdrone forum mainly supporting ArduPilot (3DR). I have a "knock-off" of that board -- the ArduFlyer. At different times, they were made in the same factory from the same components and on the same line! But of course, that's a sore subject over there. :) Now they claim theirs is made in Mexico (like that's BETTER), and they use tighter quality controls, yada, yada, yada... Not from reading the reports of failures they don't! And if you want a monopoly on your product, don't start with OPEN SOURCE! DUH! But you can't reason someone out of something they weren't reasoned into, so I let it be and get the help and info I can.

I think Dennis Baldwin also just posted a YouTube video on using APM logs to diagnose failures. In it he claims to have poured through the log data for tens of hours, so he would surely know if granular gyro and compass readings were included in any useful regularity. I could just pull some ground data from my APM-based quad and then look at it, or even introduce movement. In ground tests, I've seen what happens when a GPS loses too many satellites.

I suspect the GPS lock state does not consider the reliability of satellites when deciding if a good lock has been achieved. Satellites on the horizons are used, when I think a lock on them is less secure and continuous than those at a steeper angle. I read that it is important to have the GPS antenna above everything else, including the plane described by spinning carbon fiber props, as they are opaque to radio transmission and can impede a lock on horizon satellites. This may also explain why FPV antennas work better hanging below the craft than mounted above. Any multi-rotor that pitches or rolls is going to disturb the GPS' satellite vectors to horizon satellites, so I don't know what the answer is there. You can't put the GPS a FOOT above the drone in practical terms, and even if you did, a 20 degree roll with the motor on a fairly long arm will still shadow the GPS from low angle satellites at times.

But I ramble! ;) Good luck finding the solution, or just avoiding the problem by training that "assistant" to fly.
 
I don't know if the controllers you like to use (Naza?) use "Mission Planner" or something else, or if you routinely use telemetry radios, but here's a video I found informative on evaluating APM data.
If you had such data from the flight where the GPS (or something) allowed the quad to wander, the problem might be easier to diagnose. I'm thinking this does indicate that APM data could not only be used to diagnose problems post-flight, but also evaluate the anecdotal theory that carbon fiber props interfere with GPS reception (when the rotational plane interrupts the reception vector). While I do not think there is any indication of which satellites are in use within APM, you can get that information from a phone. If a phone at the same location as the craft finds and locks a satellite on the horizon, it is probably safe to assume the GPS on the craft did as well, and a carbon fiber plate can be used to shield the GPS in that direction and see what impact that has on flight perception and corrections produced by the controller.
 
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