Does anyone know what the CG of the Iris+ is supposed to be? I've been told at the intersection of the diagonally opposed motors which make sense but I'd like to know if anyone knows for sure. 

Ia m drifting backward and to the left a lot during flight, even during loiter. I've done nothing more than pull the quad from it's box and fly it. I'm guessing with the addition of the Tarot T-2D and GoPro 4 as well as the 600mW Boscam VTx and associated wiring harnesses I've built I've managed to get things out of balance some how. I"d like to know about what point I should be trying to balance everything.

Another question I have is related to the reaction of the Iris+ at the ends of high speed linear runs. I like to film a fast approach to an object for dramatic effect but I've noticed when flying forward rather quickly then slowing quickly the quad drop significantly then regains altitude (Altitude Hold Mode). Reverse isn't as bad but is still does it. Do I need to tune something? My friends flies a P2 and it is very good at this maneuver. I need to figure it out so I can do high speed over water and be able to slow quickly without dipping my GPH4 in the water!

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  • The IRIS has default parameters that are set at the factory so do yourself a favor and don't immediately jump into the parameter list to adjust values.

    Most likely you should do a compass calibration and an accelerometer calibration.

    Drifting around while in loiter can be caused by wind but if that's not the case then it's usually something simple like a compass calibration.


    • Thanks. So Compass Calibration is beginning to sound like the place to start. I am not super keen on tinkering with parameters just yet but if that is where I have to eventually go I will. I will definitely become more familiar with them.

      I used to program Fanuc 6 Axis industrial robots and played with parameters quite a bit to tune dynamic response during high speed path planning. I am not unfamiliar with the concept although I have a feeling the PH FC is probably more powerful than 5 of those old RH controllers combined.

      Would still love to know the location of the CG. Using the intersection of the diagonally opposed motors I appear to be slightly nose heavy and leaning to the left (looking from rear toward front).
    • The compass calibration just gets it set to where ever you are in the world so do it outside away from metal, etc.  You shouldn't need to do it again unless you crash or if a new firmware revision requires it.

      As far as tuning from the parameter list goes, you probably won't need to but any statements made here have to apply to the most inexperienced user. :)  No offense intended. :)  Lots of folks dive into the parameters as their first course of action simply because they can and things get messed up quickly!

      The IRIS comes with its' parameters set from the factory so knowing the CoG isn't as big of a deal as if you made your own copter from scratch and installed a Pixhawk on it.

      2 places that have a lot of information for you: is the product manual and has links to various procedures, sites, and videos. is the official wiki which gets updated fairly regularly.


    • Cool maneuvers for rc copters and planes are mostly programmed by the pilot into the xmitter...perhaps this can be done with the iris`s frsky xmitter....need a manual....

      In guided mode, the behavior of the iris with ref to the ground target is programmed into the maneuver selected in the tower app....seemingly.

    • Thanks for the links. I watcer the video on how to perform the accelerometer calibration. I'm wondering if there's a way I can go into the flight controller and look to see what values are in there now and compare that to the new values to see if there is an improvement after I perform the calibration b
    • Consider the Mission Planner system the test bench computer for your mUAV.The app is quite sophisticated...3DR walked me thru data download to help them determine why mine had a flyaway (gyroscope problem)
      The apps playback of your missions via tlm logs is very slick. Sensor calibration presents very cool 3D representations of x,y,z calibration points.
      The controller only shows flight critical info.battery level being the most important to me.
    • That brings up a good point. I have a verizon Ellipsis tablet that I have been trying to connect to the Iris+ via the radios with no luck. I noticed the new Iris+ M comes with that tablet. Hoping I can get it to connect song can view more data during missions.
    • I use a Lenovo ThinkPad tablet that has a full size USB port. On the Verizon tablet you have to use the blue end of the 3dr provided USB otg cable to connect into your tab.
      If the tab doesn't do USB otg you are hurtin for certain.
    • David, I would like to use my laptop as well. Where did you get the cable?

    • OK Guys here’s the run down on Video thru the Mission Planner (MP) HUD:


      Goto this page to familiarize yourself with the MP flight data screen:


      Then goto this page to read about “Other MP Features”:

      • You will see this paragraph: “You can display video from your aircraft on the Mission Planner’s HUD if you are digitizing it with the same laptop (with a video capture card or USB device). Just select the device in the Configuration/Planner screen, chose video format and press “Start” to begin recording. If you select the HUD checkbox, the video display will replace the artificial horizon in the HUD. (not all the other data tho, just the green-blue…)

      • You can also record the video that you’re displaying to an AVI file. Just right-click in the HUD and choose from the menu that will pop up.”

        Simple enough so far?  It gets interesting tho: On Amazon, the digitizer that will work in this setup is here:

        Connect the analog video out from your Black Pearl monitor (included in the 3DR LiveView kit) to the analog inputs on the digitizer unit, and connect the digitizer into a USB slot.

        NOTE:  I use a Microsoft Surface 3 Pro, which has a single USB-3 output.  I use a 4 port hub…thinking of getting a 4 port USB3 hub.

        OK, in MP, you need to configure Video-IN on the CONFIG screen:  see below-

      • 3702942541?profile=original
      • Notice the “Device”?  Your digitizer device will show up here.

        ALSO…Notice the “JOYSTICK Setup”?  -

        I also use a RealFlight simulator controller, which is essentially a Futaba RC transmitter, to control the Iris via MP.  Now you have to reduce the lag via another setting, and it’s not all that “snappy” but you have basic 3-axis control of the iris via MP thru the PixHawk Autopilot. I have tested and flown a bit with that controller.

        OK..the last item on your USB hub is the 3DR Telemetry Transceiver.  That means THREE devices on your USB hub…or use three ports on your laptop…if you intend to use a joystick controller like I do.

        You can detach the HUD window and display it on a secondary monitor, or goggles attached as a secondary display from your computer. (you’ll need a spotter tho…)

        I have yet to try this complete multi-screen setup, because I need to install shelves in the back of my Subie Outback to place all this kit in a ground station setup/system that looks professional.  I’ll send pics once I get back in the air in a month or so.  I’m looking to have something that looks like the GS for the ScanEagle. 

      I have used the Surface and the RealFlight controller in my driveway…works ok…I need to tweak it so its just right tho…

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