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Testing everything before your first flight

Perform this test after everything is installed and you believe you've loaded the correct configuration for your plane, transmitter settings, and receiver.

*** Be sure the propeller is removed from your motor, and be prepared for possible sudden spontaneous motor throttle-up in case a mistake was made in creation or loading of the configuration file.

If something is not working correctly, don't hesitate to send a recorded data file to support@uthere.com with description of problem before spending much time "scratching your head" or "spinning your wheels". Those data files contain an incredible amount of information, and we can usually identify problems with a few minutes of review.



If convenient, take the plane outside where it can more readily acquire a GPS lock.  

Turn Ruby and transmitter on.  

Re-check operation in manual mode:  

  • Pull the switch that will be used to control Ruby mode (typically gear switch) towards you to engage "manual' mode.  
    You should be able to move all control surfaces with your transmitter as you normally would without Ruby.
  • Move all controls and confirm that all operate in correct direction:

    • Move aileron stick to the right: right aileron should go up, left aileron down.
    • Move aileron stick to the left: right aileron should go down, left aileron up
    • Pull the elevator stick towards you: elevator should go up
    • Push the elevator stick away from you: elevator should go down.
    • Move the rudder to the right, then left. Rudder should move accordingly.
    • Apply a little throttle. Motor should spin.
    • Engage and disengage flaps, gear, and any other remaining controls.

If any of the servos are reversed in manual mode, reverse the channels in your transmitter settings, just as you would if Ruby were not present. Then, repeat the "ritual" to obtain an updated configuration so that Ruby will also reverse those channels.

Tell Ruby to perform a 'pre-flight'

Tell Ruby to perform a preflight calibration and system check. See [preflight instructions].

Observe what the control surfaces do as soon as you finish flipping the switch to initiate preflight. The controls should move in this order:

Right aileron + Right rudder
Left aileron + Left Rudder
Elevator up + Flaps up
Elevator down + Flaps down

If controls are moved in different order or directions than the above, repeat the "ritual" to obtain a corrected configuration.

Preflight will not end with an "OK to fly" indication unless the GPS has acquired a fix. When the fix is acquired, the red light on the GPS module will stop blinking, and Ruby will make the servos come to life. Outdoors, a wait of a minute or two after power up is typical the first time the GPS has been used in a while. Indoors, it may take a few minutes, and it may be necessary for you to move near a window or to a different room. If you're still having difficulties acquiring GPS, see [Troubleshooting GPS].

There are a number of things, some subtle, which can prevent Ruby from indicating "OK to fly". The number of wags will narrow down the problem. See [preflight instructions] for more info.

If you're not able to get Ruby to give you an "Ok to fly" elevator wag, and you're not sure why, send us a copy of your data file for review.


Check that IMU and autopilot are operating correctly

Flip the mode switch to the position to engage 'aided' mode.

Pick up the plane and tilt it in various directions. Ruby should now be moving control surfaces in a way which tries to maintain a fixed roll and pitch. Move the plane as if it were flying and responding to those control deflections to confirm that it Ruby is trying to roll to turn to the heading the plane had when you engaged aided mode, and that it is trying to keep the pitch nearly level.

As you pitch the nose of the plane down, the elevator should go up slightly. As you raise it up, it should go down slightly. The movement may be small while the plane is stationary, but will be deflected appropriately when Ruby detects airspeed.

Note that it's possible for servos to be reversed in aided/autopilot mode even if they're not reversed in manual mode. If any of the servos appear to be moving in the wrong direction in aided mode, repeat the "ritual" to obtain a corrected configuration.


Test receiver failsafe

Flip the mode switch to the position to engage 'manual' mode and briefly confirm that you have full control of the plane.

Turn off your transmitter and confirm that Ruby autopilot has engaged and moving servos appropriately as you tilt the plane in various directions.

If this does not work correctly, you have a dangerous configuration. Please see: Configuring Receiver Failsafe.


Range Test

Any time you add new electronics such as Ruby, you should perform a test of your transmitter + receiver range as indicated by the manufacturer.


Be sure that you can engage manual mode

Make sure that no matter what, you're always able to instantly regain full manual control of the plane by flipping the switch towards you.



Proper balance / center of gravity ("CG") position is critical for any aircraft. Although Ruby's "fly by wire" capability may (or may not) be able to bring an unstable plane under control, it will still fly very poorly without radical changes of settings away from standard default values, and excessive servo activity. If the plane is a little tail heavy, Ruby control of pitch and airspeed will be erratic with standard settings, and if it's too tail heavy, the plane will be completely uncontrollable with any settings. If it's nose heavy, it won't be possible to maintain low airspeeds needed for soft landings.

With all components in place as they will be in flight, support the Merlin with fingers or pivot points placed on the black wing spars.

If the plane noses up, move components inside the payload forward, choose a heavier battery, or add weight to the forward payload compartment.

If the planes noses down, move components inside the payload aft, add weight to the tail, or choose a lighter battery.


If there's any doubt, send us data

At this point, if it passes the above tests, it appears that Ruby is ready to fly.

If anything didn't seem quite right during the above procedure, please send us the data file that was recorded and wait for us to review and give an "All OK". Send as an attachment to support@uthere.com.


Cautious first flight

Some parameters can only be tested in flight, so don't assume that Ruby can autonomously fly your plane quite yet. The real test will come during your first flight. Please proceed to "Your Cautious First Test Flight".

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