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Old 02-06-2016, 11:21 AM   #12 (permalink)
toys2cars2toys
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I thought that I'd add my views, this isn't aimed at anyone in particular - some comments have already been stated, I've included them for completeness

These comments are based on no wind conditions

For coaxial helis and multirotors .... Level = No drift = stable hover
For single rotors heli....... Level Does Not = No drift or stable hover

Any single rotor will lean in hover, to the right for clockwise rotating blades, how much it leans depends on lots of factors

"Self Leveling" as in "Safe" is actually a mistruth or simplification
Actually it should be something like "stable hovering attitude" - but it doesn't sound as good (and "Safe" doesn't actually control the power, so it's not a true auto hover)
Just for now so I don't have to keep typing it, I'll make up a new abbreviation "Stable Hovering Attitude = SHA

So, lets assume that the heli has never been taught what SHA is, it simply wouldn't "Self Level" when instructed to

The AIM of this trim flight is to teach the heli it's attitude to give a stable hover with no drift ONLY when in self leveling mode

So if a trim flight is performed, the heli is taught exactly what attitude (or lean) is needed for a stable hover, for the purpose of this, lets say it leans 3 degrees to the right

Now (and finally getting to the point) if a non flying trim flight is made, if we're lucky, the heli will be sitting on the skids with the same 3 degree lean (as said before some helis are designed with an amount of built in lean) so it's all good
However, if the rotors are perfectly level when the non flying trim flight is made, then in this case, the "self leveling" will actually be out by 3 degrees

What does this mean in practice
- Both methods are good, certainly better than nothing
- Actual flight trimming will always be best as long as it's in zero wind and turbulence
- A non flying trim flight will still give good results, in the worse case only causing a small amount of drift
- If it's too windy or the pilot doesn't have the skill to hover for 30 seconds, then a non flying trim flight may give better results


BUT
The big point, is that this is a heli, designed for flying and not hovering on the spot (get a multirotor with GPS for that). The self leveling should really be considered as an aid when things go wrong at all other times the pilot should be actively flying the heli




Just a few notes about the trim flight procedure
The sequence is just to arm the setup procedure, above 50% throttle is the final part of the arming, as a CP heli will only hover above 50% throttle (assuming typical pitch and throttle curves that 99% of us use)
The controller will record the attitude (lean) during the 30 seconds and then average it out
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