Beginners part III
As promised in part II we shall now move along into the basic swashplate and flybar setup. These two components can change how your helicopter main rotor responds. Both may need to be considered together for a desired control response. Tampering here should be done only after you have mastered the basics or after you are sure of what you need.
The angular deflection of the swashplate is directly related to cyclic power. More angular deflection or tilt results in a more aggressive feel. The swashplate has angular limitations due to the design of the unit and the spherical pivot bearing contained within its center. If one desires more cyclic throw surpassing these limitations then another option needs to be considered.
Ball standoffs next to a swashplate
Often larger ball standoffs may be installed on to the rotating (spinning) portion of the swashplate imparting larger rotating control rod travel both to the blades directly (through the mixer arms) and through the paddles by way of tilting the flybar. This produces generously proportioned cyclic blade angles at the rotor head.
Both methods of increasing cyclic blade angles need to pay close attention to binding issues at all collective pitch values. If this is not checked then the risk of a departing control rod is possible in addition to the obviously stalled servo(s).
In some cases excessive cyclic throw may bind the collective mechanism or lock the swashplate to the mast. This unwanted binding occurs most with the cyclic held boxed into a corner of the radio transmitter gimbal (right stick).
Boxed right stick
Since the flybar teeters during operation, exceeding maximum rotating control rod throws may cause binding only when the flybar is teetered and thus occurs only at specific points of rotor rotation. A quick check can be made by slowly spinning the rotor with a boxed cyclic using or checking at both collective extremes when teetering the flybar.
Remember the flybar will have its largest tilt ¼ revolution after the maximum paddle pitch change so this is the respective position to check. The washout arms may exceed mechanical limitations both for lever travel and engagement on the drive pins so this area must be checked into.
Sometimes the above adjustments may not cause the machine to respond quickly enough for personal tastes. This usually can be traced to a heavy flybar, low throw swashplate or small flybar paddles. If the flybar has adjustable weights these may be removed or slid inboard equal distances to speed up the cyclic. Additionally, different paddles may be selected. Aggressive paddles often require the implementation of flybar weight to make them comfortable in control response.
Aggressive paddles often need flybar weight to tame them down.
Remember the reverse is true for a helicopter which is too sensitive and so many of these methods may still be applied. You as a beginner may adjust the above parameters in any order as the situation dictates keeping in mind that rather vast or excessive control changes can be induced by incorrect paddle selection. Make one change at a time is the best advice I can offer.
The following information offers some general guidelines for checking maximum blade pitch angles. This is best checked with tool called a pitch gage.
Typical pitch gage installation
Cyclic blade angles need to be checked with the swashplate and flybar level and at flat collective pitch (zero degrees). Values are given for each side of center cyclic stick in a +/- format. Maximum fore/aft and roll values should be the same and remember when checking to do so in the correct rotor position.
On behalf of the fore/aft axis, the blades need to be positioned over the port/starboard, and for the roll axis over the nose and tail boom. When making the check hold the cyclic stick to the respective extreme, turn the receiver off for a more relaxed viewing.
Pitch gage used to measure roll cyclic blade pitch values
Beginner = + /- 5 degrees cyclic
Advanced = 6 to 8 degrees cyclic
Collective values must be set with a level flybar and swashplate
Beginner Full up collective = +8 degrees
Beginner Full low collective = 0 to -2 degrees
Beginner Half collective = +5 degrees
Advanced = +9 to +11 degrees top collective depending on engine power
Advanced = -9 to -11 degrees bottom collective depending on engine power
Advanced = 0 to +5 degrees half stick depending on flying style
Forward speed affects how the helicopter handles or how sensitive it becomes with fore/aft cyclic inputs. This is because the rotor and flybar disks have become slightly unbalanced due to one half receiving rotational airspeed plus forward air velocity while the other side receives rotational airspeed minus forward air velocity.
It is rather complicated in theory but generally speaking that’s it in a nut shell. A light flybar will often cause the helicopter to become sensitive or pitchy during the fast forward flight mode. What you tune for in a hover may be excessive elsewhere.
When you advance and become a very good flyer you may then decide what is best for you. What is good for one person may be much less so for another, so my advice is not to be too concerned by what others tell you are the absolutes. Feel free to experiment within the scope of these guidelines.