Jim, the Thunderbird was a budget ESC for RC use, and doesn't have the constant RPM (control line or heli) mode.  You can use FM-9 with it, if you choose "battery voltage compensation" mode when programming the timer.  It will adjust RPM as the battery voltage drops (you can choose the compensation rate).  Not as good as the Edge / Phoenix / Talon series, but good enough for trainers and such.

If you haven't already bought the FM-9 timer you might look at KR Timer.  It works well with cheep ESC.  It provides RPM control and other feathers.  Easy to program.  All it takes is a program stick and a tac.

ESC with governor for Heli an controline are available today for very low prices.

Flying, even with sport models, is a poor experience without a governor. Although you can compensate for the battery's voltage drop throughout the flight, the motor's RPM will drop during maneuvers. This forces you to run the motor at a higher throttle to compensate for the drop in RPM during maneuvers.

I can recommend the YEP ESCs from Hobbyking or the ICE/YPG, which are the same, from the same manufacturer, in appearance and functions. They use the same programming card that has soft start, brake, battery protection, governor, governor store, governor high, freewheeling, P-gain, and I-gain functions. You will need to purchase a programming card, but it is not expensive.

There is the more expensive Hobbywing Platinum, but I have never used that one.

Finally, there are the very cheap ZMR ESCs with BLHELI firmware (not to be confused with the V2, which I am not familiar with) that can be programmed by computer like the Castle ESCs. They have governor high, low, P-gain, and I-gain functions and are very affordable. However, you will need to buy a USB dongle, and sometimes it can be a little difficult to install the drivers for this USB device.


Douglas B