Thanks for the info. I did make some progress by making a contra-rotor design, and it was much more stable, but I'm still running into strange behavior in flight. The aircraft constantly wants to roll to one side and pitch up. The faster I go the worse it gets. It does let up when I reduce the authority limiter on the blades slightly but then I also lose altitude. Also, I have the pitch, yaw, and roll controls linked to the blades. I'm not sure if that's a good idea or not. But during flight rolling to the left also causes the aircraft to pitch down, while rolling to the right causes a pitch up behavior, and when I roll I also yaw. It's actually more effective to use the roll controls to control pitch than it is to use pitch controls. Maintaining a steady course, speed, and altitude is an insane balancing act of keeping the nose down, messing with yaw constantly to stay on course, rolling to control pitch and roll, and fiddling with the authority limiter of the blades to keep altitude and reduce what seems to be a retreating blade stall.
I haven't messed with the Kal-1000 just yet tho. My goal was to make a relatively low tech helicopter for short-medium range surface science contracts in career mode, so I'm trying to stick to early to mid game tech. I'll keep messing around with it tho, see if I can figure out what's going on.