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Skookum Robotics Skookum Robotics SK-360 SK-540 & SK-720 Digital Flybar


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Old 01-07-2013, 12:30 PM   #1
npomeroy
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Default Asymmetrical swash - software correction?

During the fitting of the scale fuse to my T550 there was minimal clearance for the left and right swash links, so (along with more fibreglass removal) I replaced the lower swash balls with ones that were approx 1.5 mm shorter (maybe less than 1.5, difficult to measure now that the replacement balls are loctighted onto the swash). This gave much nicer clearance. But I could not find an equivalent rear ball (i.e. with the long bit for the antirotation bracket slot) so did not change that one. The upper swash radius is 25mm and the lower radius reduced from 38.5 to 37 mm (approx). By my calculations this gives about 4% increased head-link movement from the right/left servos compared to the centre servo.

I think the logical correction (if one is needed) is to decrease the travel movement of the right and left servos in the software, by 4%. Any objections?

I've had the heli flying quite well with fuselage-equivalent weight ballast (before the swash ball change). My servo travels are on the default 125%, Swash mix is 47 - 47 - 37. Servo arm radii 21 mm. I may go through the swash setup again - is there a case for reducing servo travels to 100% and increasing the swash mixes?
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Nelson JR DSX9 II; DX6i (relegated to the Phoenix sim), Atom 500 in AS350 body (retired), TRex 450 S in MD500E. Trex 450 S for sport practice. TRex550 in Funkey/Century Jet Ranger. SK720 all round. SR120 (abandoned). MCP-X.
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Old 01-07-2013, 07:26 PM   #2
npomeroy
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I flew the heli this morning (maiden in its fuselage) on the above settings and swash balls and it behaved OK.

After that, I found an earlier thread on "servo travel".

So I have in fact reduced all my swash servo travels to 100%, and changed the mixing to 55 - 55 - 44% to get the pitch angles I wanted. I couldn't see a particular change in the movement symmetry so decided against any compensation for the slightly unequal ball lengths.
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Nelson JR DSX9 II; DX6i (relegated to the Phoenix sim), Atom 500 in AS350 body (retired), TRex 450 S in MD500E. Trex 450 S for sport practice. TRex550 in Funkey/Century Jet Ranger. SK720 all round. SR120 (abandoned). MCP-X.
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