I flew the helicopter with the same electronic equipment (Spirit GTR, Theta cyclic servos, YGE BEC, etc) for 75+ flights without issues as a 580 size helicopter.
When I stretched the helicopter to a light weight 700 size heli, I decided to also try the 760µs center pulse on the cyclic servos with Theta servo programming box. After a few success flights, the helicopter leaned left and forward during a spoolup, and caused some damage. I attributed this to being fairly windy for a light weight and fairly floaty helicopter, and perhaps not having the collective stick at mid-stick. After I rebuilt the heli, the helicopter again leaned left and forward during spool-up. During this 2nd rebuild, that's when I noticed the initialization issue. My best guess is that the spool-up crashes were due to spooling up without verifying proper and complete Spirit FBL initialization.
Now that I know about this finicky initialization, and I found a good way around it, and the fact that the helicopter is flying well otherwise, AND the fact that I plan to replace the GTR units with W1 units as soon as they are available (hopefully soon
), am thinking of just shelving this "temporary" issue as good enough for now, and move on to other projects in the meantime.
***************EDIT*******************
The problem turned out to be the Theta Razor DH1 Low Profile servos. The problem is NOT isolated to Spirit. This problem happens with VBar EVO units as well. The problem manifests only when these servos are programmed to 760µs center pulse. No issues at all when these servos are programmed to 1520µs center pulse. I have not tried other Theta servos to test, but so far (as of 02 Jan 2024), this issue seems to only affect the low profile standard size Theta servos and not other Theta servos. I removed the YouTube videos as I do not want folks associating this issue with Spirit units when in fact it is a Theta servo issue.
