I flew my stock TREX 450 Pro yesterday for nine batteries, and it was in perfect trim. All landings were just perfect. I put the heli in its aluminum case, kept it in the garage overnight, and took it out again today. I went to the same field, the weather conditions were the same, I used the same batteries - but the heli needed four clicks of forward cyclic trim to stay level! Yesterday my cyclic forward trim was centered, so it's not that I changed the trim by accident. I tried to move the battery forward as much as possible, but that didn't help (the canopy is a very tight fit, so the battery basically always ends up in the same spot anyway).
Just for completeness: I used that same transmitter (DX6i) for my neXt simulator after yesterday's flight, but I'm using a separate model for that, of course.
Does anyone have any idea what could be going on?

Trim Change

Is the pro fbl??
If so, all sub trims should be at "0"
If not, the rubber dampeners can get a slight flat spot with blades folded in the case which will popback ... or if you power up while blades are still folded it can strip a link on the threaded rods..
Hope one of these might help you figure out what changed.

Good luck
Stan

AMA 2918-Team Spin Blades,,Castle Creations, Unique Aircraft

It's a flybarred Pro, so no weird gyro issues here.
Is it really conceivable that a single night in a (rather cool) garage would cause the head dampeners to get a flat spot? I'm also trying to imagine how that would affect cyclic trim.

One More

The flat spotting is most likely not your problem, but something that could happen.
Check your flybar paddels to make sure one didn't get bumped while going into the case!!??

Stan

AMA 2918-Team Spin Blades,,Castle Creations, Unique Aircraft

I checked the flybar paddles, and don't see anything obvious.
I would also naively expect that any kind of asymmetry in the rotating part of the head would result in a vibration, not a drift (=being out of trim) in one particular direction. But I don't know enough about helis, I guess.

Paddles

You would be correct if the distance was different from each paddle to center..but if the leading edges of the paddles are not on the same plain it could definetly cause your problem..
You might want to post in the Align 450 forum to get more help..

Stan

AMA 2918-Team Spin Blades,,Castle Creations, Unique Aircraft

I'll double-check my paddles. The swash is level and stays level through the entire pitch range, as far as I can tell by visual inspection. So, the problem has to be in the rotating part of the head, as you say. Though I didn't see a problem with the paddles, it is entirely possible that something is out of wack, because it is a pretty tight fit in that Align case. I wish they had made it such that the heli stands upright instead of laying on its side, but that's beside the point here.
I must admit that this still really puzzles me, because I cannot see how it would result in this backward drift. Why wouldn't these unbalanced forces just average out on each revolution of the blades and cause a vibration, instead of pulling the heli backwards? I would be more than grateful if you or someone else could explain this to me.

Just a stab but , Make sure the servo wheel did not strip and move a bit. Generally happens in a crash but you never know.

taus

Good idea! I'll go over it on the weekend; looks like it'll be too windy to fly anyway...