North Coast RC Modelers

I want to share a few heli setup tips that are not too common but still sort of helpful.

Level the swash without removing the head.
Most typical swash leveling tools require removal of the head.  I often level mine without removing the head by wrapping a piece of tape, zip tie, wire or twist tie around the main shaft, then bend it down until it just touches a swash ball link, then rotate the shaft to see if the other ball links are at the same level. This can also be used to level the swash at the full up and full down positions using servo ATV settings.

Level servo arms with a drafting square.
Some of my servos are not mounted perfectly square so I check the level of my servo arms by aligning them 90 degrees to the main shaft by sighting them with a  drafting square.

Flybar leveling may or may not be critical for pitch measurements .
I use a drafting square to line up my Trex 550 flypar at exactly 90 degrees with the main shaft and lock it before measuring blade pitch.  However, I don’t worry about leveling the  flybar on my Exi 450 heli.   Trex 550 measurements are very sensitive to the level of the flybar, a one degree angle on the flybar will cause about a one degree error in the pitch angle.  The Exi 450 has hardly any pitch error even if the flybar is several degrees out of level.   I think the difference might be because of the design of the mixing control arms; straight control arms being prone to errors; angled control arms being relatively immune to flybar position.

Unequal positive verses negative pitch.
Flybar mixing control arms need to be accurately leveled in order to get equal positive and negative pitch ranges.  This seems to be more of a problem with arm designs that have a downward angle on one side.  The bent angle makes them hard to visually determine when they are level.  If your setup results in too much negative pitch you can either lengthen the three swash-to-servo links or lengthen the two swash-to-control-arm links.  The choice depends on which will best keep the washout arms level and keep the head from binding at full throw. Changing the length of the washout-arms-to-flybar-cage links doesn’t seem to have much of an affect on anything other than the head clearance at full positive pitch.

Adjust tracking without using colored tape or a pitch gauge
Instead of using colored tape to determine which blade is tracking  higher, I position the head at mid collective, then fold both blades back until they touch, then I suspend the blades by pushing down on the  opposite flybar paddle.  The blade that sits highest is the one that was tracking high.  An accurate way to position the head at mid collective is to temporarily change the radio’s swash pitch setting to zero (Futaba 7c).  A handy way to check for equal zero degree blade pitch (if you already removed the blades) is to slide both blades sideways into their blade holders at mid blade, like a teeter totter, and check that both blades are parallel to the flybar, no pitch gauge is needed.

Loaded verses static pitch
I wondered why my helicopter felt sluggish even though I was using recommended pitch settings.  I discovered that there was a lot of flex and slop in the old worn out head.  I made new adjustments by measuring while I gently twisting the blades towards more pitch, until I felt resistance. That way I could determine the true pitch angle that would result under load.  The heli flew fine with the new pitch settings that were way above normal if I measured them like normal but were just right when the blades were pushing air and under resistance of an actual load.

Disorientation during flight
Sometimes I lose orientation during flights and was puzzled for a solution.  I spent some time observing my disorientation on a simulator and learned that it happens most often when the heli is 50 feet or more away, traveling to my right, pirouetting clockwise, and the disk has been level with my eye (looking thin) for a few moments.  I found I can best prevent it by concentrating real hard on the lean of the disk while the heli goes through that particular situation.

Ever wonder what would happen if you flew with one blade mounted upside down?
I got in a hurry and so accidentally mounted one of my blades upside down (one leading edge was facing backwards). Surprisingly, it didn’t act strange while spooling up, but as soon as it lifted off that backwards blade grabbed a whole bunch of air which twisted the blades further into the wind.  The heli rocketed up at warp speed and as soon as I lowered collective it shot back down. With some blind luck I stuck it down with very little damage.

Do you have any uncommon tips?