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Your cautious first test flight with Ruby

Even after you've successfully performed the "test before first flight" and we've reviewed the data recorded during that test, there is still a potential for hidden error in your installation, configuration, or understanding of how to use Ruby. Such errors will not be manifest until you engage Ruby aided or autonomous mode in the air, and might only be evident in data recorded from that flight. If there has been a mistake in configuration such as reversed elevator and you did not detect this in the "test before first flight", Ruby will immediately try to dive the plane into the ground as rapidly as possible.

So, we ask that your first flights with Ruby be cautious and tentative ones, that you provide us with recorded data and accounts of your first flights whether or not everything seemed to function correctly, and that you wait for our review before starting to "lean" on Ruby. Besides allowing us to spot possible problems, this gives us a chance to ensure that you'll be able to use Ruby to your satisfaction and its fullest potential.


Besides reviewing the [warnings], please follow these guidelines during your first flights:

  • At ALL times, be ready and able to assume immediate manual control to bring your plane back and land.
    When in aided or autonomous mode, ask yourself continously "Could I shut off Ruby and bring the plane back manually right now?"
  • Launch and land in manual mode, not aided or autopilot.
  • Get plane up to high altitude with plenty of room for recovery before engaging Ruby aided or autopilot mode for the first time. At least 200 feet altitude. Remember that some configuration or installation errors can cause Ruby to immediately go into a dive.
  • Engage aided mode for the first time very tentatively, with no throttle, being prepared to go back to manual mode the moment the plane begins to do something unexpected. Ruby should never dip the nose more than 30 degrees or roll the plane more than 60 degrees under any circumstance.
  • If aided mode appears to be maintaining solid pitch and roll, move the throttle all the way forward to engage altitude lock with aileron/elevator stick centered, and see if Ruby is able to maintain altitude gracefully. Hold the stick over a little to keep Ruby flying in gentle circles rather than let it get too far away.
  • While still in altitude hold mode, move the aileron progressively further to the side to tell Ruby to fly progressively steeper banked turns. See if Ruby is able to hold constant bank angle and altitude. The controls should feel responsive, following your stick with matching bank angles. With stick all the way to the side, you should see Ruby attempting to maintain a 60 degree banked turn.

  • If aided mode seems to work OK, test various autopilot modes. See that you're able to engage and identify Ruby in these modes:

    • loiter at current position and altitude
      (depending on your plane, Ruby will be configured to circle at anywhere from 75 to 200 foot radius)
    • return home and loiter
    • begin auto-land (but just let it run briefly, not to perform actual landing)
    • temporarily override course by moving aileron from center

Don't be lulled by autopilot mode during these first flights. Don't let Ruby take your plane to the point at which you would not be able to visually maintain orientation in manual flight. This can happen quickly with a small plane.


By default,, Ruby's auto-land mode targets a final entry point that is 600 feet away from home. For some people, this may be beyond visual control range, especially with a small plane. Exit auto-land mode and bring the plane back. Contact support@uthere.com if you have a wide field with no obstructions and would like a configuration file allowing a lower landing pattern and shorter final approach.

Note also that if battery voltage dips below 10.5 volts while Ruby is loitering, even if just due to a combination of high throttle and battery age or thin power leads, Ruby will leave loiter mode and enter auto-land mode. (This will only happen in autonomous modes, not aided or manual.) If you think you've engaged autonomous loiter mode but Ruby starts to fly away in a straight line. and it returns to that heading after you use the aileron override to turn it away,, it's probably in auto-land mode.

Fly with flight data recording

Whenever Ruby is powered up with a SD Flash chip inserted in the Expander, it records with a myriad of flight parameters such as wing load, airspeed, control inputs, and system voltage, as well as many variables internal to Ruby, all with high time resolution. A new file is automatically created on the SD Flash every time you turn on Ruby. [more about data recordings].

We ask that you always fly with expander attached and SD Flash chip inserted because this data is invaluable to us when troubleshooting. A 2 gigabyte SD flash chip can record many hours of flight, so you can essentially just leave the chip inserted and forget about it. The files look like any other computer files when the chip is plugged into a PC. Once we release the ground control software to the public, you'll also be able to enjoy reviewing and learning from this data yourself.


Planes not in the supported aircraft list

The first time you engage aided or autopilot modes with a plane not on the supported aircraft list, for which a tuned configuration file does not exist, the following may occur:

  • Underdamped / "nervous" / "spastic": Plane have rapid oscillations or "nervous" behavior in pitch and/or roll axes or throttle.
  • Overdamped / "sluggish" / "drunken": Plane may not maintain or reach target roll or pitch or altitude, or may get into long, slow, deepening pitch / airspeed / altitude oscillations. Note that sometimes there is a delay of 30 seconds or more before such oscillations become evident, and that they can become "runaway" with increasing amplitude once they begin.

If your plane is well balanced and flies well manually (and maybe even if it doesn't), then any of the above can be corrected through changes to the configuration file. support@uthere.com is standing by to assist. Just send us your data_#.utd file from the flight and describe what appears incorrect in flight behavior, and we'll get an updated configuration file right back to you.


We won't be satisfied until Ruby is flying your plane in a solid, responsive, and graceful way that gives you confidence.

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