Spirit System

Hello there,

I own a TRex700 nitro and have still issues with the governor function with the Spirit RS. After some month of absense I reactivate the Trex yesterday, First flight was quite fine, the requested head speed is 1715rpm and the system hold it more or less at that level. After landing and disconnecting the battery from the system I wanted to make the second flight, but this time the system spools up the head speed to more than 1900rpm and fix it there. What is going wrong at the second flight and why? Completely same setup (same TX, same model, same trottle curve) as 5mins before but much to high head speed.
The TX is Jeti DS12, and it logs and displays the current headspeed. Unfortunately the headspeed at the second flight is realy to high, its not only visible at the RPM-value at the TX-display, its also hearable very well. I also attached the pictures of the log-rpm-diagrams of first and second flight.
I need your support to understand what is causing this misssetting of the headspeed at startup in order to secure a stable headspeed at startup at all flights. Thank you very much for support in advance.

best regards, Kay

Hello,

it seems difference is in headspeed you were starting from.
When spooling up nitro you have to always leave Governor to do so from Idling RPM. Not to do it manually with throttle curve.
So from approximately 8-15% to target RPM. It seems you were over 50% TC when engaging Governor.

oh, I do as you are describing already, the pics of the diagrams are zoomed to see the rpm more in detail and so the spool up from zero is not visible. For understanding, why exactly does this influence the headspeed as it is set by a fixed value from the trottle when engaging the Gov?

Thank you and best regards, Kay

...in addition, the spoolup (after setting the trottle curve to a straight line for activating the governor) never starts at really zero rpm as the clutch is not separating perfectly. After engine start and putting the heli to the airfield and getting back to the pilots area, the headspeed has already raised to a certain speed, but I did not care about that yet. I assume it could be 300rpm at the first flight because I wanted to warmup the engine a little bit.
Would the spirit need realy zero headspeed when engaging the gov? I hope not, but if so, what would happen if I cancel an autorotation?

best regards, Kay