Maybe I was lucky and got the Altitude Hold (AH) worked the very first time. After I have the V2.5.5 firmware installed and fixed my latest crash, my AH no longer work. Once I switch to AH mode, the heli immediately slammed onto the ground with negative collective pitch. It happened once way before V2.5.4 and I thought it was an isolated incident. Luckily I already have a very strong 500 landing skid mod on this 450 and a set of plastic golf balls as landing cushion, there was no damage.
Anyway, so I played around with the PIDs and noticed that it had no effect at all. Finally it dawned on me that it could be the trim. So I went to the Heli Setup, Swash Travel, and changed the Collective Zero to a higher number! Voilà! It hovered and AH!
So, in case your heli jump to way high or slam onto the ground when switching to AH, change your collective pitch zero setting in the Heli Setup page.
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Thanks Wes, I'll have a look since I've got your params loaded in my 450 now. I did a test hop yesterday and it went OK, except I find the rudder isn't working well.
Did you set yours up with mechanical trim on the rudder thrust? I found that with your rudder settings, I had to hold right stick to stop it rotating. The Yaw I term should fix this, so you must not have enough. However if you set it up with mechanical trim, then it might work out.
I prefer to set it up with zero mechanical trim, and then let COLYAW and Yaw I term sort it out.
Wesley,
Thanks for the report. The collective zero should really only affect the angle boost (i.e. how much additional collective pitch is applied when you lean over more). Still, maybe you've stumbled onto a bug so I'll try and have a look and see if there's really a bug there. thanks again.