Cinestar Loses power during flight for a few seconds. Watch Video

Discussion in 'Cinestar 8' started by Chris Newman, Apr 27, 2013.

  1. Chris Newman

    Chris Newman Member

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    First time i've seen this in a year of flying. As shown in the video around 35 seconds the heli loses power, and onboard low voltage warning comes on. ( I didn't get a telemetry response on my spektrum, buy my telemetry is crap these days) As I see it fall I crank the throttle and it responds. I have add battery failure before but when that happens the heli flips upside down and away it goes. This time it seem it was more kind of gliding down motion.

    Not a fun experience, especially infront of the client!

    The same thing happend on the flight immediately after this. The next 2.5 hours (rest of the shoot) it was fine.

    Has anyone experienced this or does anyone know what the issue could be?

    Thanks in advance!
     
  2. Brad Meier

    Brad Meier Active Member
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    FC type, batteries, etc used? Data log available? I assume you checked for any loose connections before the second flight..
     
  3. Sedric "Zellevision" Sari

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    BL temp maybe... gpx file and HW setup needed I guess :)
     
  4. Chris Newman

    Chris Newman Member

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    Mikrokopter FC , 8000mah 4S batteries (1 month old) I don't have a data log available.
    I have the setup just need to install.
    The video above was the first time it happend. After I landed I switched out the battery with a fresh one and it happened again. So i'm thinking it was not a battery issue.
     
  5. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Chris:
    Whoof. That's a heart-stopper.
    It sounds and looks like ALL the motors reduced power as there was no tendency to yaw or roll. So that suggests it is something in the technology common to all of the motors. I didn't hear any beeping, just a throttle-back.

    It's really hard to point the finger at the likely cause without flight log data as the only evidence we/you have is the video. You've eliminated the battery, so what's left? The FC, I2C bus (Molex connector to power distribution board), the connector from the LiPo to the power board, or the power distribution board itself.

    It is JUST possible that the issue is transmitter related -- and that the Tx "commanded" a throttle-back when it should not have, but, again, without the GPX file, we cannot tell that.

    Please post again if you have any more information that comes to light.
    Andy.
     
  6. Ozkan Erden

    Ozkan Erden Distributor

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    I wouldn't trust on the molex connector solely; I would solder C-D lines and batteries (+ and -) between PDB and FC.
     
  7. Chris Newman

    Chris Newman Member

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    Hey Andy, I know that the onboard voltage alarm goes off. If you crank your speakers around 35 seconds in you can hear it. Knowing that, does that narrow it down at all? I appreciate everyones help!
     
  8. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hey Chris:
    I've listened to that video several times over using Genelec near field monitors -- double check me here, but it sounds like the "J-Code" for transmitter signal lost. I hear dit-dah-dah(-dah) -- the last "-dah" is obliterated by motor noises as they throttle-up.

    Do you year that? It certainly doesn't sound like dit-dit-dit....which is the low voltage alarm on my C8.

    What do you (and anybody else think)?
    Andy.
     
  9. Chris Newman

    Chris Newman Member

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    Hey Andy,
    I think you might be right. I've only heard the Low voltage alarm while flying so I just assumed it was that.

    So.. If the the trasmitter signal was lost could that mean I need a new satellite receiver or a new transmitter? I have been flying in super dusty conditions recently.

    I just now recalled, about 30 min after the dropping episodes it felt like there was some sand or junk on the throttle side of my transmitter while flying. I will see if I can open up the DX8 check for debris.
     
  10. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Chris:

    Well, first off, I was wondering whether there might have been any cell phone towers (or other transmitting antennae) on the buildings near which you were flying? They could simply have swamped the signal from your transmitter -- come to think of it, if anyone inside the buildings had Wifi nodes, those could have swamped the signal too. WiFi is on 2.4Ghz too, so that's a possibility as well.

    Have you had any repeat of this signal loss/throttle down in other locations since this incident?

    How are your MK Boards set up to react to transmitter signal lost? Do you have a Navi Control Board/GPS with Emergency Come Home set?

    The possibility of crud in the throttle gimbal on your Tx would seem to be unrelated -- I don't think that could trigger a transmitter lost alarm....

    Andy.
     
  11. Shaun Stanton

    Shaun Stanton Active Member

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    I think you lost "RC comms" flying near that building. I had had the same thing happen to me. It looks just like a battery low indication, but you get the flashing LED's underneath the copter, but no voltage warning. What I believe happened is the roof of that building has an HVAC system with a power distribution cell. The power distribution cell will cause electromagnetic disturbance that can disrupt the 2.4 signal causing a intermittent loss of communication with your controller. I do not think anything is wrong with your controller. My guess is the first two flights you flew it right in the perfect "Sweet spot" to disrupt the signal. The next flights you probably managed to keep it out of that spot. If you could post a screenshot of your MK tools setup page, Misc tab?

    My guess is that you lost link with your DX8 in the same fashion that mine did and your system went into emergency gas mode, hince why the sudden loss of power, until your link restored and you were able to recover it. If you have the GPX file as well that will be even better, because it records what events cause certain anomalies on your SD card.
     
  12. Chris Newman

    Chris Newman Member

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    Hey Andy,
    I was on the same block as Utah's major TV news network and the building was a college so i'm guessing there was plenty of wifi around.

    This incident happened last night but I filmed for 2 hours at different locations afterwards and didn't have the issue at all.

    I have the GPS navi just but have never installed it. Now might be a good time!

    Shaun!
    I'm glad someone else has had a similar issue! I hope your right it was isolated to that location. What is emergency gas mode? The heli just lowers slowly until it receives the signal again? I don't have the GPX. Doh.

    So where were you when your incident happened?
     
  13. Gary Haynes

    Gary Haynes Administrator
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    All sorts of antennas on the top of that roof. Also next door to the Utah State Capital with a bunch of Sat dishes on the rooftop.

    Screen Shot 2013-04-27 at 3.47.05 PM.png
     
  14. Chris Newman

    Chris Newman Member

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    I checked out the second incident and I was about the same height as the first incident but I was over the street.

    Thanks Gary! yeah I think that confirms it! I feel little better now. :) After this location we actually filmed at the capitol building (we got permission in exchange for footage) and I flew all over that thing with no issues but I was farther away as it's a huge building.

    Thanks for everyones help!
     
  15. Steve Maller

    Steve Maller UAV Grief Counselor

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    I just threw up in my mouth a little. Oh man...
     
  16. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Definitely install the Navi Board. Get a 2GB microSD card, formatted for FAT16, and install it into the slot on the Navi Control Board.
    Do you have the GPS unit with GPS shield? Install that too! You can't rely on it, but it will give you a Position Hold when you need it, along with a manual Come Home (back to where motors were started with a GPS fix existing), as well as an Emergency Come Home if the Rx loses contact with the Tx. Remember to set your emergency Come Home altitude appropriately for the job -- the copter climbs or descends to that altitude for Come Home (regardless of whether it's Emergency or Manual).

    Emergency gas is an MK Tool setting that is a percentage of the hover power (as determined automatically by the MK Board) to which the throttle will be set when the MK Boards lose contact with the transmitter. It's basically an "autoland wherever you happen to be." Or, if set wrong, "autocrash in front of client." ;)

    I would avoid any such similar locations -- you're lucky to still have the bird! :)
    Cell towers, WiFi, broadcast antennae, power lines, phone lines, trees, yellow snow. They're all in the same group: Avoid! :)

    Andy.
     
  17. Chris Newman

    Chris Newman Member

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    Thanks Andy, I will scrounge up my navi board gps stuff and get it dialed in. I will make sure and ask about cell towers, wifi, antennae when discussing shoots with clients before hand!
     
  18. Gary Kaplan

    Gary Kaplan New Member

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    Chris,

    I see you are using a Spectrum DX8. What receiver are you using? Are you using a satellite receiver connected to the main unit? Where is your receiver mounted on the heli and in what orientation (and where and how is the satellite receiver mounted)? Also, do you put your DX8 antenna at an angle when you fly? If so, which way do you can it positioned? When you returned from your flight did you notice the LED on the Spectrum receiver flashing or was it lit solid?

    I know I've asked a lot of questions but they are for good reason. You may have just had a temporary "brown out" (dropped data packets) from the DX8 Tx to the heli's Rx. The receivers LED will be flashing if you did, and the number of flashes will tell you how many times it dropped out. Even if you didnt lose control at all during a flight and everythuing went OK you could have had dropped packets. The LED on the Spectrum receiver will tell you. If it comes back and it is lit solid you did not drop any packets and if it is blinking you did.

    Also, the best way to eliminate a power issue to one (or more) of the ESC's or motors or a drop in one or more of the battery cells, or just voltage "sag" from the battery is to have data logging. If the data shows you all is well in the power department then it was definately a RF issue. If you can first eliminate any potential Tx/Rx issue (from the questions above) you can start to look elsewhere. My experience in RF and in R/C has taught me one valuabe lesson; your heli is trying to tell you something. You said "Its never done this before". Pay close attention to what it is telling you, its very important. When something like that occurs and then happens again but later "goes away" you should be very concerned. Don't ignore it just because it hasn't happened again. If you attach some pictures of how and where your receivers are installed it would help greatly. RF signals (like the Spectrum 2.4GHz system) have both vertical and horizontal polarization. ALL RF antenna's whether they are used for Tx or Rx have dead spots, areas of low gain and high gain (according the the angle of polarization) and need to be properly positioned in order to make sure you always have the best chance of having a link between your DX8 and the receiver.

    Cheers,
    Gary K.
     
  19. Shaun Stanton

    Shaun Stanton Active Member

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    Mine happened at an Old "Santa Fe Railyard" Maintenance depot for steam locomotives and later diesel. It has been abandoned since the 80's. It serves as a movie set for a lot motion pictures and TV shows whenever they need to shoot in a dilapidated industrial area. In fact the specific incident where it happened was a spot that was used twice in the show "Braking Bad" I lost link at the same spot where a character named "Combo" gets shot on the TV and the Main character Walter White runs down the individuals who did it in later episodes. I digress just some fun facts on where it happened. Now for the relevant stuff.

    My incident was little more aggressive because it happened almost immediately after takeoff here is abridged version.

    1. Takeoff and climb to about 25 feet or so
    2. Hear a sudden loss of power and copter drops.
    3. Power restores a bit and have control see LED's flash and copter drops some more.
    4. Get control again, arrest the descent, realize something isn't right. Make an effort to land.
    5. LED's blink again copter descends until hits the ground, luckily on all landing gear with no tipping:)"I hate broken props"

    After analyzing the GPX file I had several lost RC comms and 4 emergency land indications. Some of the RC com lost I still some control although the copter was not as responsive.

    What I thought was the cause originally, was a construction sign which had a drone radar gun. But a later found out when that sign was gone that the electric disturbance was most likely due to a power transformer station that was about 50 feet away. I was able verify that the 2.4 GhZ signal would seriously get disrupted when near that station. I performed a test flight with my 550 Hexa. And confirmed that at 20 to 40 feet in the air the signal would get disrupted. I launched from a different spot and flew it to the area. Sure enough as I descended towards I would loose link and it would initiate its return to home function. It works a little different on my Hexa because I am using ardupilot on that bird instead of MK. The concept is still the same But the RC receiver and batt telemetry are the same spectrum equipment that is on my CS8. My hexa actually has redundancy that the CS doesn't possess, because I have to use the AR8000 and DSMX satellite. So even two 2.4 systems were able to get disrupted in that area.

    My CS8 went into Emergency gas mode because I had it set improperly. Under Misc tab in the Koptertools there is a setting for failsafe Come home time. If this is zero, the copter will not enter the automatic return home logic. It will fall or climb at what ever emergency gas setting is. There are two ways to set that.

    1. One is a vario failsafe metheod, a little check box. If that is not selected then the copter automatically sets the throttle gas number 0 to 255 on what is in that box. If that number is too low then the copter will fall fast. If that number is set too high than the copter will climb and climb until it finally runs out of power and crashes. This is not a preferred method because it is based on several variables such as payload weight density altitude, and other factors, it requires you to constantly test how much throttle gas is required for hover and descents. You need the telemetry module such as blue tooth and your laptop to monitor these settings.

    2. The preferred method is to check the vario control box. If vario is selected, now the number becomes a percentage of how much gas in reference to what is required for a hover. The flight control system figures out how much throttle gas is required to hover as reference, then sets the throttle gas to the percentage that you select. If you selected 100% the copter will maintain a constant hover. If you select 95% the copter will goto 95% throttle gas required for a hover and will descend. Important thing to keep in mind here is if the setting is too low you may stall the rotor blades because the descent rate will be too fast and it will fly in its own wash, a phenomenon known as "vortex ring state". Once the copter enters this it will progressively get worse as the more rapid descent happens until the props are longer efficiently producing lift and therefore will descend rapidly until ground impact.

    3. And final. In order to use Comehome Fucntion you need the Nav board with GPS. The GPS needs to have at least 5 satellites acquired. Ensure there is not any solar activity to disrupt a healthy GPS signal, or else the copter may return to the wrong spot. You need to have Failsafe Come home time set at a number higher than 0 no larger than 60. This gives you 60 seconds for the copter to return back to launch spot and descend and land. After 60 seconds are up the copter reverts to emergency gas and will descend at the rate I mentioned above for an additional 27 seconds. After 27 seconds hope that your copter is on the ground, because it will be shortly after the motors shut off in flight no matter where the copter is and crashes :eek: Thanks Holger!:mad:

    Here is my incident with a GPX if you so choose to look at it in this thread. http://forum.freeflysystems.com/ind...today-by-a-portable-construction-marque.1000/

    Shaun

    No I did not get the phenomena again in with CS, only with my hex while doing a controlled test flight.
     
  20. Cris Olariu

    Cris Olariu Member

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    Had one of these episodes myself a couple days ago. I was at a park in the area. I somehow managed to position myself right under some power lines. The CS8 took off just fine, flew it to about 40-50 yards out, at about 80 feet altitude, then all of a sudden noticed a drop in altitude. Was able to bring it back safely. Stupid me, didn't really think twice about it, and kept flying in that same area. Flew right under the power lines too, which in retrospect was a stupid idea. Once I got home, I took a look at the GPX file. OMG!!! I guess sometimes it's better to be lucky than good! MK Version: FC HW:2.1 SW:0.88n + NC HW:2.0 SW:0.28n Flight date: 4/27/2013 9:21:26 AM Flight time: 9:21:26 AM - 9:26:30 AM (304 secs, 00:05:04) Batt. time : 314 secs, 00:05:14 Elevation(GPS) : 0 116.16 250.26 ft (min/avg/max) Altitude(Barom.): -4.27 109.77 243.44 ft Vertical speed : -17.06 -0.03 12.63 ft/s Max speed : 21 mph Max target dist.: 47.4408018 ft Sats : 10 9 11 Voltage : min. 14.5, max. 16.4 V Current : 16.3 50 90.7 A Wattage : 248 775 1343.98 W Capacity: 4389 mAh Motor1: 2.4 7.8 20.2 A Temp: 77 138 169 °F Motor2: 1.6 4.5 10.0 A Temp: 79 129 153 °F Motor3: 3.0 7.8 15.4 A Temp: 91 156 189 °F Motor4: 0.6 4.2 7.6 A Temp: 99 136 162 °F Motor5: 2.1 7.0 15.4 A Temp: 97 142 167 °F Motor6: 1.2 4.4 9.9 A Temp: 88 124 145 °F Motor7: 0.7 8.0 13.2 A Temp: 77 144 171 °F Motor8: 0.4 4.6 8.4 A Temp: 73 129 160 °F Magnet Field: 100 104 111 % (ok) Magnet Inclination: 50 58 70 deg Errors / warnings: Error "RC Signal lost" (7) occured 47 times! FC-Flag "Failsafe" (2) occured 24 times!
     

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