Cyclic Pitch, Servo Reverse and Swash Mix - DX6i

[firemanphil]

  Have a read at the CYCLIC RANGE paragraph of this  http://www.kempley-helicopters.com/guides/ccpm-setup  (bottom of last page)  the question is if it's - or + 11 degrees then surely that's 22 degrees ie -11 then O then +11, if not explain where they get 17degree range. next the dx6i pundits say if one servo is moving wrong way then go into servo reverse and alter it, EASY   then they say if MORE than one servo is moving the wrong way go to SWASH MIX and alter. Why not just use the servo reverse,as all servos are in the menu? or can it not be done that way?  

[Rumblecloud]

 

And he did such a fine job of detailing everything out, you'd think a small detail like 5° wouldn't go unnoticed.

Perhaps math is not his strong suit - or maybe he actually knows something he's not telling us.

Regardless, I'm with you mate and need further enlightenment on the missing 5°

r

[Wayne]

No, you cannot program a swash by only reversing servos.  Reversing a servo just reverses that servo, but reversing the swash mix reverses the way all three channels are mixed together.  I'm not sure that comes across very clear from my description?  Try to think of the elev control.  When you move the elev, it does not move a single servo but all three (pitch and aile go down and the elev servo goes up).  If you just reverse the elev servo, then all three will go down instead of just reverising the effect of the control movement.  Good grief, I've probably confused you more now than when we started  

[Wayne]

Ok, I follow him on the cyclic as well.  What you are thinking, correctly, is if you have +/- 11, then your total range of the collecive is 22.  What he is talking about is cyclic pitch + collective pitch.  For example, if you had full positive pitch and threw the cyclic (aile or elev) full range one way or the other, you would have +17 (11 deg collective + 6 deg cyclic).  You would not add the total range (22) to cyclic as you are either going to have +11 or -11 at a time, not both.  Making any more sense?  This is quite a standard setup for a 450 and will not get you into much trouble.

What you have to be careful with is some of these new 600s and 700s out that have +/- 14 collective and most guys at that level are setting up 8-9 deg cyclic.  What you have then if you go full deflection collective and cyclic is a potential for +/- 23-24 and that is beyond the critical angle of attack and could stall the rotor.  If you are close to the ground when that happens, you may plow it in and not have any idea what happened.  Critical angle of attack on most of these blades is right around 20 deg, so keep that in mind if you get yourself a heli that has a head that will physically allow more pitch than that.

[diggiz]

OMG.  Thats so damn confusing. maybe its just too late for me. Im glad my heli is set up and working and I dont have to try figure that out   Im sure it makes sense to others, im just not that technically minded.LOL

[firemanphil]

  Wayne i want you to think this one out for me  each servo can be altered (reversed) individually,so to use your example ,elevator if it was moving in the wrong way,servo reverse it,now it's moving right way. so why can't you do all 3 servos,if you can do 1?   

[Wayne]

Ok, here we go, another attempt to explain it, not an easy subject you picked here.  The reason you can't just reverse each servo is because your cyclic movements do not control just one servo at a time.  When you move the elev control you are moving all three servos, not just the elev servo.  Same when you move aile, you are moving all three servos, not just the aile servo and same for pitch...

You have to be able to reverse the mixing, not just the individual servos, in order to achieve proper movement in all direcitons for swash control.  Maybe stated this way, reversing a servo only changes operation of that servo, not the other two that are mixed with it to produce the desired movement.  Sure, you can reverse those too, but then when you go to move on the other axis, chances are you are going to have a mess.  It takes a combination of servo direction and swash mix to accomplish the proper setup.  Sometimes you might get lucky and just have to reverse one servo and you are good, other times you will have to make several attempts at reversing one or the other servo AND reversing the swash mix.  The bottom line is to use a combination of these adjustments until you get the proper movement.

[firemanphil]

  Wayne,i could'nt have made any clearer!!!!!!!!!!!!!!!!!!!!  it is quite a complex concept.

[papascotimini]

That's a pretty good explanation Wayne.  I was having this problem with my HK250 setup but now everything is moving in the right direction 

Happy Flying

Papa