so what size do you guys recommend tethering a quad for starting up for the first time.. 600 series?
chris.
Here's how I'd answer that. The worst-case scenario on a spinup is that something goes wonky on the PID controller and the motors all go to full. Or maybe the copter starts oscillating like crazy and shakes itself to pieces, while clattering all over the room in the process. So now ask yourself: if I throttle up and that happens, am I willing to accept the consequences? If the answer is no, then the copter should be restrained on first throttle up. If the copter is capable of seriously injuring you, seriously damaging something expensive in the room, or damaging itself to a point where you'd be upset to have to fix it, then it should be restrained on first throttle up.
With my mini quad, I always do a hand-held test after any configuration changes or after changing a prop where I throttle up and tip it forward, back, left, right, and feel that it pushes back correctly. I also feel for oscillations. I started doing this after once accidentally setting P gain to 25 (the max value) on Luxfloat, which resulted in the copter just taking off for the moon, oscillating wildly, the second the throttle left zero. I cut throttle and it fell from about 30 feet and landed on my Mobius and destroyed it. I mean, you think that if you just give it a little throttle, then you'll catch any bad tendencies and throttle back, but that's not what happened with my mini quad. There were two settings: to the moon, and off. And what if your brand new FC has a damaged gyro or something and does a flip of death?