FROM THE DESK OF TED SCHOONARD

Mechanical Collective Set-up for X-Cell Kits XL-Pro 1006 differs slightly but follows similar principles.

This set-up may apply for normal to 3-D type conditions depending on pitch range utilized. Long or short mainshafts makes no difference in the procedure.

Exact rod dimensions are not the best way to achieve the correct set-up Please follow the following steps in-order.

1. Determine the pitch range desired. A typical 3-D set-up might use +9 degrees to -9 degrees with throttle hold at +10 degrees (This would apply to symmetrical blades only). For standard (3674-1) kit blades use +10 degrees to -6 degrees with throttle hold at +12 degrees. In each case, select the maximum desired pitch and adjust a pitch gauge to about 1/4 degree more than that amount.
   
   
2. Disconnect the following rods:

   	Washout to flybar
   	Elevator yoke to swashplate
   	Roll bellcrank to swashplate
   	Roll servo to roll bellcranks
   	Collective to roll servo



3. Put the pre-set pitch gauge and flybar lock on the blades and head. Manually raise the swashplate (in a level attitude) fully up until the washout hub will not allow more travel. At this time adjust the #0335 Hiller rods until the correct top pitch is shown (+1/4 degree).
   
   
4. Manually raise the #0157 elevator yoke and swing arm #0155 until the yoke stops under the top collar under the upper bearing block assembly. Adjust each #0227 fore and aft pushrod until the above elevator yoke is fully up at the same time that the swashplate is fully up. Match this adjustment to the (2) #0227 rods connecting the roll bellcranks to the swashplate.
   
   
5. Now, make a small reference mark on the side frame level with the swingarm pivot pin #0161 and/or the M3 lock nut you see outside of it (1003, 1004 kits). Next lower the swingarm/swashplate assembly fully down to the bottom of its travel or until approximately 5.0-10.0 mm exists between the swashplate and the upper frames. Make a second small reference mark in a similar manner at the lower end of the swingarm travel. Use a ruler to measure the center point of these two marks and add a third mark. This third mark will correspond to the center of the total pitch range. For example, had you chosen +9 degrees with +10 degrees as top at throttle hold, your actual total mechanical pitch range chosen is to be +10 degrees to -9 degrees. Therefore, in this example, the true mechanical center is at +1/2 degrees. This is the pitch value you want to see at the center mark we just made. Actual pitch values will change based on your selection, but the idea remains the same.
   
   
6. Adjust the two #0371 roll rods until the following condition is satisfied. The swing arm and elevator yoke are aligned on the center reference mark and the roll servo is exactly vertical (as viewed from the side) and the roll bellcranks are neutral.
   
   
7. At this time the collective to roll servo pushrod can be adjusted so that the collective is at neutral (center of given travel range) and the roll servo is vertical as in step 6.
   
   Now, the exact position of the collective servo wheel upon the servo spline/arm (the adjustment of a push/pull mechanism if one is used) is to be determined. This is a bit difficult at first since you must take into consideration the following:
   

   	Where you'd like zero pitch to be on your transmitter.
   	The amount of collective ATV to be used. Obviously you want ATV to be maximized through your selection of servo wheel output and pitch curves. Most all modern radios offer easy adjustment in these areas.
   	Each component i.e. servo wheel, push/pull arm, ETC are all neutral at the same time. These are basic considerations in any heli set-up.

8. After the collective is set-up "approximately", it is time to reconnect the two #0337 flybar control pushrods. These are left till last for specific reasons. In order to properly make their adjustments, the roll and elevator (fore & aft) ATV adjustments must first be satisfied. Put a pitch gauge on the blades and a flybar lock and position the blade over the nose and one over the tail. Carefully adjust collective at the transmitter until you read exactly zero degrees pitch and avoid touching the collective again. Give a full right roll command and adjust ATV until a maximum of 6 degrees is read at the blade. Adjust left for 6 degrees also. Low rates can be about 4 degrees if you like. Now rotate the blades till the flybar is over the nose and the tailboom. Re-confirm exactly zero degrees collective and set elevator ATV for 6 degrees maximum either way.
   
   
9. Now the #0337 flybar rods can be adjusted. There is an acceptable 2 to 3 turn range for their adjustment. But the following condition must be satisfied:
   

   	At full or about +9 degrees collective and full cyclic the upper ball link on the #0337 rods do not touch the bottom of either blade holder. If they do, it is indicating that the pushrods are adjusted too long and should be shortened.
   	At low collective and fully cyclic, the lower ball links of the #0337 rods do not strike the base of the head block #0289. If so, the rod lengths are too short.

10. The final adjustment is to adjust collective ATV to remove the extra 1/4 degree initially set on the pitch gauge at top pitch. This will relieve the "bottoming-out" situation we initially used in the swing arm adjustment and swashplate travel under the wash-out hub.
    Double check for actual "bottoming-out" at low collective also.
    
    
11. Flight Conditions:
    The most common mistake made by the beginning 3-D pilot is over-control. This is primarily the result of not having the proper information and of course "nerves." While the latter will only be helped by practice and diligence, information is a bit easier to absorb.
    
    Most advanced 3-D pilots will tell you that the actual collective and cyclic pitch required to perform flips, tumbles and most other 3-D/Hot Dog maneuvers is far less than you may think or are currently using. This is an important bit of information. Keep in mind that "stalling" a heli blade is quite easy to do in todays situations. The stall point of most symmetrical airfoils is about 11-12 degrees. As the airfoil approaches this range of pitch , it's efficient lifting capability drops significantly and it's drag coefficient increases in a similar amount. This progression becomes proportional greater as pitch is increased. What does this mean to the heli pilot? The by-products of this phenomenon are excessive blade noise, lead/lag and tracking problems and greater engine loading. Each condition can potentially damage your helicopter. For these reasons, the pitch and cyclic range should be optimized (not maximized) for best performance.
    
    Since collective and cyclic pitches are flown simultaneously in 3-D, it is recommended that a conscious effort be made to "exchange" cyclic for collective during hard 3-D maneuvers. For example, in a "hovering tumble" most beginners will almost automatically utilize full negative collective while using full cyclic during the maneuver. The speed of "tumble" is no greater or the maneuver any safer simply because excessive control was utilized. Say for example that +/-9 degrees collective was used briefly while +/-6 degrees of cyclic was introduced. This means that the advancing blade of each rotation had as much as 15 degrees of pitch at the same time that the retreating blade had 3 degrees. The advancing blade is past the approximate stall point and is now creating a great deal of drag on the system. This same blade will lead/lag significantly different from the retreating blade holding 3 degrees. Of course, this is all happening for only fractions of a second.
    
    But it is a continually on-going condition. It is quite reasonable to do the exact same maneuver using no more than +/-5 degrees collective and +/-5 degrees cyclic by simply making a conscious effort to only give the minimum required commands. This will ease the power demands, lessen any chance of linkage over stressing and produce similar tumble rates without the blade tip noise. This is the way an expert would do the maneuver and be able to safely repeat it hundreds of times.
    
    All too often the inexperienced 3-D pilot's solution to slow cyclic rates is to simply add more and more mechanical cyclic travel. This approach totally ignores the "stall principle" and blindly hopes that "nature" will look the other way. We have very little control over the natural effects of air over a given blade airfoil, so this method is not recommended. This is why we adhere to the +/-6 degrees of cyclic throw. It is far more within our control to dictate cyclic rate by varying the following:
    

    	Flybar paddle size, shape and weight
    	Rotor blade length and center of gravity
    	mechanical ratios such as bell mixers and flybar control arms.

    
    These variables can make significant changes in cyclic response without creating conditions that will cause failure. The only consideration here is to keep rotorblade span and chord C.G's within acceptable limits.

The Colorado Rotor-Heads is a group of R/C helicopter pilots based in Denver, with members all along Colorado's Front Range.  Our members belong to many of the Front Range clubs from Colorado Springs to Fort Collins.  As a result, you may see our members at many of the local club fields and even the occasional cul-de-sac.  If you would like to learn more about the Colorado Rotor-Heads, or R/C helicopters in general, please visit our web site at www.coloradorotorheads.com.

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