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sireric
11-03-2006, 01:53 PM
Hi.

Well, I crashed my CCPM 450 after about 50 flights, while doing low height figure 8's. I actually broke a lot of the head elements, the main body and rear boom/tail assembly (almost cried). So I'm rebuilding using a CF body and mostly metal head/tail pieces. It's pretty much an SE now. The servos have a single link direct to the swashplate, in a CCPM fashion and they sit horizontally just below the plate in the top of the CF body.

I've made the body and installed servos (still using HS55). I've leveled the swashplate in all pitch positions, by mechanically leveling at middle sticks and setting end points at extremes (per video).

However, when at the lowest pitch (left stick), if I push the right stick down all the way too (basically, the rear servo is already low and I ask it to go lower), the servo is straining. In a similar manor, if I go full pitch and I push the right stick all the way up, the servo is straining again.

I've tried reducing the swash pitch gain from ~60% to ~25% to remove the servo strain. However, when I do that, I don't get a lot of travel from the swashplate, from going from lowest to highest pitch with a centered right stick. So:

1) Is it better to have a lot of swashplate travel but limited forward/reverse at extreme pitch levels (I can just "avoid" those places)?
2) Or is it better to have limited swash plate travel but allow for the max pitch+forward to go to the limits of the servo? Same for min/reverse.
2) Should I consider different servos, though it would seem to me that all should do this?
3) Is there some mechanical change I could make for this?

Thanks any advice!

sireric
11-03-2006, 11:11 PM
Extra info: I just got back on it, and I see that when I push the pitch to maximum and then push to max on right stick, the rear servo's link rod actually hits the anti-rotation bracket. That's what's causing the servo to strain.

I'm not sure how to fix that.

sireric
11-10-2006, 01:22 AM
Update (for those who care):

1) Switching the ball on the links to 13~14 mm from the servo arm center fixed the elevator arm hitting. I saw that in the Finless video (sets it to 13 mm).

2) The control rods for the swashplate were just too short. It's odd, but the SE manual sets the pitch/aileron rods too short compared to the elevator, at least in my setup. Needed to add almost 1.5 mm to each of pitch and aileron to match the recommendation for the 40.3 mm on the elevator servo. This lifted the swashplate about 1.5 mm and centered it very well. I had the elevetor rod too short before.

3) After that, I was able to leave the ail/elev/pitch swash gain settings at 50%, and it's the full movement, with no bindings at either end from the servos.

4) Re-watched the whole ccpm interaction video again. Learned more again ;-) I leveled the swashplate using the tool, but then got all the head subsections level. Now, the tracking appears dead on, I've got +10/-10 on the pitch and +/-6 on the ail/elev (all within 0.5 degrees).

Looks really good now. I'll fly it this weekend and check it out.