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Flight Test Log 18

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Summary
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A new autopilot and GPS receiver was flown in two test flights. The autopilot
now includes adjustable gains on both the aileron and throttle controllers.
Also, a broken wire was found and corrected in the 6 VDC power supply to the
control system.

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   Test_ID:  48
      Date:  2006/06/28 (Wed)
      Time:  19:30 (approx)
      Wind:  Breezy
   Vehicle:  SVC
     Scale:  55 %
      Mass:  --
     Pilot:  Robert Wagoner
  Location:  PCC West Campus
 Elevation:  730 m

Our new Picopilot and GPS receiver were installed in SVC 55 and flown in two
flights. The new autopilot has adjustable gains on both throttle and aileron
controllers. Reduced aileron gain seems to have cured the roll oscillation
problem we were seeing previously. GPS waypoint tracking still needs work,
however.

During preflight checkouts we discovered a broken wire on the 6 VDC voltage
regulator that supplies power to the autopilot, R/C receiver and elevon
servos. Fortunately the problem was discovered and corrected before the first
flight of the day. A magnified version of the picture shows more detail. The
picture was taken after the wire had been manually pulled out of its
insulating sleeve on the voltage regulator.

The loose or broken wire may explain the problems we had at the 2005 IARC
competition, when our first flight was temporarily delayed because the
autopilot kept rebooting itself on the ground and the motor controller would
not initialize (see the August newsletter of the AIAA Tucson Section, page 3).
Possibly the wire had been making intermittent contact. We suspect a bad
solder joint.

Prior to 6/28, it's possible the wire problem had existed undetected over the
previous year or so, during which time a number of flights had been made. We'd
never seen an in-flight power failure during any of those flights, perhaps
because of sheer luck.

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Last updated 2006/07/01 FLM