Quadcopter battery and controller consensus?
Hi all...
My Quadcopter is built, and I have a few questions.
1) What RC controller seems to work best? I bought a Futaba T8FG Super, but I can't seem to find the gain setting. I've always used Futaba in the past, but I never needed to adjust gain.
2) What battery seems to work best? I had a few Venom 25C 5000MAH 7.4V batteries from another project, but I'm not sure they are going to work with the Quadcopter. Do the batteries need to be 11+V, or will 7.4 work? Is there a specific set of battery parameters that seem to work best with this device?
I had no problem calibrating the ESCs, and everything responds correctly, but the Quadcopter won't lift off. Could this be an indication that 7.4V isn't enough? It -almost- lifts off, but it won't actually leave the ground. I can get brief flight by applying directional control, but that really only succeeds in coming close to flipping the Quadcopter over. It still won't take off.
Ultimately, I'm going to pair this up with one of my Propeller "brains" for autonomous roaming and exploration, but I need to get it flying first. :-)
Thanks...
Jamie
My Quadcopter is built, and I have a few questions.
1) What RC controller seems to work best? I bought a Futaba T8FG Super, but I can't seem to find the gain setting. I've always used Futaba in the past, but I never needed to adjust gain.
2) What battery seems to work best? I had a few Venom 25C 5000MAH 7.4V batteries from another project, but I'm not sure they are going to work with the Quadcopter. Do the batteries need to be 11+V, or will 7.4 work? Is there a specific set of battery parameters that seem to work best with this device?
I had no problem calibrating the ESCs, and everything responds correctly, but the Quadcopter won't lift off. Could this be an indication that 7.4V isn't enough? It -almost- lifts off, but it won't actually leave the ground. I can get brief flight by applying directional control, but that really only succeeds in coming close to flipping the Quadcopter over. It still won't take off.
Ultimately, I'm going to pair this up with one of my Propeller "brains" for autonomous roaming and exploration, but I need to get it flying first. :-)
Thanks...
Jamie
Comments
You really need a 3 cell (11.1V) battery. 7.4V, if it works at all, would not be good for the motors or ESC.
The motors do not draw a lot of current so you do not need a high "C" battery. 10C would be okay, but I would prefer a bit more just for peace of mind.
I use a 4500 mAh battery. 4000 to 6000 mAh is appropriate but there is a preferred physical size that will fit under the control board. Hopefully someone will share the details of that. I don't know since I mount my batteries underneath the frames.
I was suspecting the 7.4V battery as the culprit, but hearing that it needs to be 3C solidifies that. I'll go ahead and grab an 11.1V battery in the mAH range you specified.
Again, thanks for the information - I can't wait to see this thing map my property without running into anything. :-)
Jamie
I got it back home, charged it, connected it to the ELEV-8, and it powered up as normal. I armed it and increased the throttle slightly, and the engines spooled up MUCH faster than they had with the 7.4V battery.
After disarming it, I took it outside, armed it, and prayed.
Being a pilot of real aircraft, I throttled up slowly, and the ELEV-8 lifted off smoothly to hover at about 10' (that's AGL for all of the wiseguys that are going to read this). I applied very gentle right stick, and it veered to the left and I was barely able to throttle down to prevent it from crashing into the ground. It was a hard landing, but any landing you can walk away from is a good one. For the ELEV-8, any landing that doesn't require a Crash Kit is a good landing. :-)
After checking all conncetions, I armed the ELEV-8 and went for a second go. Again, the ELEV-8 veered in the direction opposite that of my control input (the Futaba is supposed to be reversed, according to the documentation), and crashed hard. The little bugger is remarkably resilient, so I still didn't need a crash kit.
On the third flight, it was apparent that the battery was losing power (it's only 2100 mAH), so the ELEV-8 lifted up to about 5 feet (again, AGL), then promptly flipped over to the right and crashed very hard, breaking a propeller. When I got to it, I found that two of the power fittings had come off (the connectors came apart), which explains the sudden violent loss of control. Thankfully, that has never happened to me in a real aircraft! NOW, I need a crash kit, which I'll be ordering in a few minutes.
Fortunately, I don't need propellers (only engines) to test the control input reversal, so I'll be doing that over the next week or so while I wait for the crash kit.
To summarize, my takeoff problems were definitely indications that I was using the wrong type of battery. An 11.1V battery is necessary. Also, the engines seem pretty resilient. I plan to buy different propeller fittings, because the ones that came with the engines are not optimal. Some of them will not fit as far onto the engine shaft as the others, so my ELEV-8 would never have actually balanced with the propellers that came with it. I'm not sure the controller would have enough control authority to compensate. When I receive the crash kit, I will be sure to use a sizing reference tool to ensure that each propeller is exactly the same amount on the engine shaft as all of the others. Finally, the engines and propeller fittings shown in the documentation were not the ones that came with my kit, so the build process might be a little different depending on your propeller fittings.
The build was really not that difficult, but there were areas where it was necessary to improvize. There are huge holes (big enough to fly an ELEV-8 through) in the documentation and build instructions, but a modicum of understanding of what you are trying to accomplish will get you over the hump.
This was my first attempt at building a Quadcopter, and I am just about 100% satisfied with the ELEV-8. I want to know more about the flight controller, but that will come with more successful (and longer) flights. I would love to see better documentation - especially related to testing to see if your ELEV-8 has been assembled and built correctly, but I assume that will come with time. Any 1.0 product is going to have gaps. Finally, while I understand that Parallax is VERY clear that this particular project is not for beginners, I would have liked to have seen some guidance with regards to radio controllers and especially, batteries. I have built other Parallax products that required RC batteries, and all of those products (IIRC) gave some type of guidance with regards to the batteries to be used.
Parallax - another excellent product! You guys continue to impress me. Thanks! To whomever engraved my controller cover with "Happy Anniversary", I give my heartfelt thanks. This ELEV-8 was a surprise gift from my wife for our 20th anniversary, and that extra few minutes of engraving made this gift very special for me. Little things like that are the reason why Parallax will NEVER have to compete for my business.
To everyone that helped me get this thing in the air - Thanks!
If I can help anyone, my email is jpole@jcpa.com - I'm happy to provide any kind of assistance.
Jamie
I'd like to get 20 minutes of flight time, but I'm not sure if that's possible yet.
Jamie
With no control input it will resist any rotating (pitch, roll, yaw) movements you make. It will keep trying to get back to it's original orientation.
With the motors still running you can move the control stick and verify that it tries to go in the intended direction with little risk to the craft. The risk to you depends upon how much throttle you use and how well you hold it.
I can't believe I didn't think of doing it that way first - I guess I was just too excited to get it off the ground. I'll try that (with no propellers, of course) in the morning.
Thanks again for your assistance with my battery issue.
Jamie
My line of thinking is that the control inputs are directed by the flight controller, so as long as the controller has power, and there are engines present, it should try to stabilize the "flight".
At this point, I just want to figure out the reversed lateral flight controls - forward and reverse seemed to work just fine. I expect it's probably just a setting in the RC unit - I don't think it's a problem with the ELEV-8. I chose the "X" configuration rather than the "+" configuration, so that might complicate the troubleshooting process (if the problem turns out to be something other than the RC unit).
I'll update this thread as I troubleshoot.
The ELEV-8 was definitely amazing while it flew. I can't wait for it to fly for just a little longer. :-)
Jamie
You won't be able to tell which way it is trying to stabilize without the props installed.
I am not sure if you said you wanted your controls from your Transmitter to be inverted, but you can change that in the Settings of the transmitter so that Left stick goes left, and right goes right. Also, the optimal battery is an 11.1V 3S 30C 4400mAh battery. Through all the battery configurations we have tested, the 4400mAh seems to be the peak of the power to weight ratio. Any larger and you are required to use extra throttle to keep the craft up, thereby reducing the overall flight time. Any smaller and you just simply get a shorter flight out of it. As for the control board, it does not do any auto-leveling or correction of flight currently. If you give it left stick, it will not come back to center until you give it an equal amount of right stick, and the same goes for all the directions of flight.
Regardless, I received the crash kit(s), and replaced the propellers. The propellers in the crash kits were completely different from the ones that came with the original kit. The crash kits also came with different propeller hubs (this is what I would call them on a real aircraft - I'm not sure what they are called in the ELEV-8 context - they are the fittings that attach the propellers to the motors). These hubs will not fit on the engines that came with my original ELEV-8 kit, which are not even close to being the engines that are shown in the documentation.
Once the propellers were replaced, I started troubleshooting, and I found that I had only reversed one of the joystick channels on my controller. Once I reversed the second channel, the ELEV-8 flew just fine. It is a little difficult to control, but as with real aircraft, that will get better with practice. For the moment, I'm working at keeping a stable hover, and making (very) minor lateral movements. The lateral controls work as expected, so the problem was definitely that I forgot to reverse the second joystick channel. Next time I'm home, I plan to monkey around with the altitude hold function.
I find it extremely amusing that I have never so much as scratched a real aircraft, but I have crashed the ELEV-8 several times. :-)
Jamie