OK, Houston I have a problem! But I got pretty lucky as I didn't damage anything. My C8 wants to nose over and go to the left when I start my motors. When I start my motors I put the left joystick straight down and to the center and leave it there. You can see what I mean in the video. Before I started the motors, I calibrated the gyro's. I double checked everything, I made sure the motors are spinning in the right direction by doing the motor test, I made sure each boom was level like Andy suggests in the video. I then double checked to make sure the battery tray was level both ways and I then recalibrated the level by hitting the left joystick up and to the right. I then recalibrated the gyro's again and tried it again. Same thing. I had my wife put the c8 above her head and I tested it. The controls seem to work in that I mean when I yaw left and right it does so, when I Roll left and right it does so, and when I nicked down and up it did so. However I found that the neutral spot for the right stick was slightly down, and to the right. I noticed that there was more throttle when I put the right stick in the middle position as opposed to being neutral. I wasn't sure if this was normal. I went back inside and triple checked everything. I checked the MK tools settings, I checked the booms to make sure they were tight and level with respect to the hub, and I triple checked the motors again with the motor test. I inspected the props to make sure they were not damaged. I checked to make sure all the props that end in P are on the odd booms, and that all non P props were on the even booms. Next I went down to the baseball field that has a large open lot to test. Same thing upon start up (you will see in the video), but this time I got in the air (I just had to) I wanted to see how it responded. When I got it up in the air it was behaving very similar in that it went forward and to the left. I corrected it and it was controlling in the directions as I was trying to control it but I was struggling a little because it was definitely needing more roll right. In my inexperience I got the C8 a little too high and a burst of wind just took it and I believe it stalled the motors and it feel like a brick. I was pretty lucky though as it feel into the field where there was 2 to 3 inches of snow so it cushioned the fall. Luckily enough the snow didn't damage the electronics and I pulled the power as soon as I got to it. As you can see in the video I have GPS lock all the way through the crash. I even double checked to make sure the GPS was calibrated properly by taking the coordinates and putting it in Google maps. It came right on it within 10 feet. One last thing, I made sure I was in free flight mode, GPS was off, altitude hold was off, carefree mode was off. OH, and before Andy asks me, I did not have a micro SD card in the nav board sorry to say. Upon inspection everything seems to work well just a 3 broken props.Here's the video So now I got to ask why is my C8 behaving this way at idle and upon initial take off? I did not have the gimble on it, and I just stuck a cheap Go pro 2 on top with stick tape. Here's my settings that I have in my MK tools Mixer setup Octo 2 Gyro P 100 Gyro I 120 Gyro D 20 Dynamic stability 65 ACC Faktor 27 ACC comp 32 Main I 16 Drift compensation 0 Gyro stability 8 Yaw P 100 Yaw I 120 Min Gas 8 Max gas 230 compass effect 64 The only thing I can think of is that the FCB isn't level but the battery tray is when I calibrate the level. I say that because when I took it apart to dry out the boards I noticed that the FCB nuts had just a little bit of slack on one side. I would say like 1/16 to 1/8 of slack. Anyone have any suggestions? Can anyone tell me how I can adjust PID to compensate for the forward nick and slightly left roll the C8 behalves like at idle??? I'm more concerned with the behavior of the C8 than I am with the crash because I'm pretty sure that it was just my stupidity flying that high with the wind conditions. I also had no gas going when the gust of wind came as I was trying to get the C8 lower. I think it was just bad timing and inexperience.
Hi Dave: Glad to see that the damage was cushioned by the snow. (Note to self: Snow makes a good safety cushion when test flying.) I fret about those high voltage power lines just to the left of where you were flying, though. Did you calibrate the compass for that location? I can see/hear that you calibrated the gyros before flying. Did you by chance have a microSD Card installed in the Navigation Control board? If so can you upload the .GPX file that would be logged the flight so we can see what happened. Gusts of wind cannot stall the motors, so something else happened. If we can see the GPX file then we can see what it was. The motors actually appear to stop at 1:58. Is there a chance that you were throttling back and putting in left yaw and accidentally stopped them by accident. Also, during the flight there seems to be an awful lot of yawing going on -- that suggests again that the compass might not have been calibrated, but I'm not sure. The settings you have don't see too way out of line -- but just out of curiosity why you're not starting with the defaults? Let's start with the GPX file if you have it. Andy.
Dave. When you calibrate the ACC are you using a bubble level to ensure that the ship is dead level? Other thing could actually be the GoPro. When I tried to fly mine with the GoPro mounted on the battery deck it seemed to put off enough RF that it affected the MK electronics. You should be able to fly with the default level 3 of the MK tools. You might check to see that the trims are centered on the MX-20. Those are the little switches next to the sticks on the MK. On the screen you will see two verticals and two horizontals. There is a hash mark that moves as you make adjustments to the trims. They should be centered. And you have checked that Alt Hold, Postion Hold, etc are turned off?
Good thoughts, Gary. That relentless yawing in the video is worrying -- the trims could certainly do that. Andy.
Hi Andy NO SD card was in the bird at the time unfortunately. I did not calibrate the compass for that location, I calibrated the compass at my house 1 mile away. I checked the GPS and got the coordinates of where it was, plugged it into Google maps and it came up with the exact spot I was at so I believe the compass is good to go. Could I have been throttling back and putting it in left yaw? Yes absolutely cause I was trying to get the bird at a lower altitude. I thought those were the default settings? Do you know what the default PID should be?
OK, I think you are on to something. My roll and nick, and gas are not centered when the joystick is centered. See pic i attached. How do I adjust them so that they are centered when the joystick is centered? Also when you say default level 3 of MK tools do you mean that I can go to level through hit reset and it will give me back the default settings? Eager to hear back from you, thanks for the help!!
Dave Here is a spreadsheet file that I got off the the web that has all of the defaults. https://docs.google.com/spreadsheet/ccc?key=0ArfrElQnmjucdFFPX3dYZ1d1VnFyLXI2S1FLQUVaemc#gid=0 There are 5 'modes' in MK Tools. The standard setup is usually '3'. You should see that on one of the first screens in the expert mode. I haven't seen Andy's DVD but it is probably discussed there. See the snapshot at http://www.mkmanual.com/mikrokopter-tool/mk-tools-tabs/configuration If you are running the MX-20 there is a way to calibrate the sticks. Look at page 20 Joystick Calibration.
Check to make sure all motors and props are spinning the correct way... wondering if it's possible that you have a motor going the wrong direction but the copter was still able to compensate enough to fly? That crash was scary! Had that been over the pavement it would have been a different story. Also I noticed that it was making the beeping like it lost it's connection with the TX. Did you turn off the TX before you got to the copter?
If you're using an mx20, there are trim adjustments on the front panel. They're the little switches next to the joysticks, and their settings are right next to the joysticks. Are all the trim adjustments at their center settings? See here:
The constant beeps at the last portion of the video after the crash. It beeps continuously which normally means a signal loss. Josh
Hi Dave: Unfortunately the geomagnetic field is not really based on proximity -- it varies because of local influences, fences, metal pipes, power lines, concrete rebar, etc. The motor stop sounds like it might have been accidentally induced by you then -- otherwise I'm scratching my head and other parts trying to figure what could cause it.... The default PID settings are: Gyro: P 100 I 120 D 10 You can actually reset everything using the exclamation mark in the red triangle at the bottom of every MK Tool Window, but you might want to use the "Save" button to save a copy of the current settings before you nuke the settings -- just in case. I realize it's 20/20 hindsight, but if I could whimper persuasively and ask you to put in a microSD card to capture the flight logs it would be so much easier for you (and us) to help figure what's going on.... Thanks Andy.
When you do put a micro SD card in do a few tests and make sure it records to the card! I have had cards not work. Had to buy 2 cards before I got one that does work. Needs to be 2gb or smaller and formatted FAT16. I'm using a 2gb Patriot memory card and haven't had any issues. Josh
Good news, I found my joysticks trims off (3 of the 4). It was strong on throttle, roll left and nick down which is why it responded the way it did. I did not have the motor kill switch activated after the motors were started and I bet anything that I killed the motors in the air. I will get a micro SD card tomorrow and try it again
I've used SanDisk without any problem. The are a bunch of "cheapy" brands that do not work particularly well. Andy.
Cool. That explains a lot. Think carefully before you enable the Motor Safety Switch. There's a strong argument against using it because you want to be able to turn the motors off in a hurry. The only reason you may have accidentally killed the motors is because of the out of trim situation. You will not ordinarily use zero throttle and hard yaw left -- not even if you fly like I do. Andy.
OMG!!!! That was painful to watch. Had to close my eyes. You're lucky that the bird is still in one piece. Thank God for Carbon Fiber!!!!
The motor safety switch, once you have some power on the engines, and are up in the air you cant disarm the motor, not untill you land. Atleast not me, I tryed it to be sure I have it on a "safe" switch on my mc32, I have to lift up the switch before I can flip it over, so its impossible to do it by mistake.
I wish there was a way of disabling those things. I find that they get bumped a lot, especially if you have a neck strap attached to the center post of the mx20. I now include a visual inspection of those every time I am about to take off. There is audible feedback when they are moved, but that's easy to miss.
Thanks everyone for the help! This forum is OUTSTANDING. I feel much better now as I have fixed the joystick trims, they were "WAY" off. Take a look at the picture I attached, these were my center positions for the 2 joysticks (Channels 1 through 4). Gary I would have never thought to look at that, thank you so much.