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I now have considerable time using Vario's new two bolt blade root head. The purpose of the dual bolts at the root, eliminate the lead lag which the blade would go through while flying, making it somewhat unstable some of the time. This new head fly's very nice if set up properly. Your radio setup is very important to the way this head fly's. The basics with the setup include having no subtrim on the elevator, aileron or collective movements. This will give uneven from center throw on the servo. By just rotating a four star arm around the servo, you should be able to place the arm perpendicular to the servo at half stick. You also do not need allot of throw for the servo for this head. Leaving the percentages at 50-60% set in the swash section of your radio should be fine to get the desired pitch range needed to fly this head. If your radio does not support electronic swash rotation in the CCPM mode, you should consider using the offset swashplate which Vario offers for the Skyfox, Benzin, or Extreme mechanics. This swash, when set up properly, gives the needed 45 degree offset of the swashplate movements needed to phash the head properly. You would set your rods going to the blade holders from the inner ring of the swash perfectly parallel to the main shaft. To get the proper position of the swashplate lock, place one blade parallel to the tail boom. While giving a fore and aft movement with the radio, this blade should not move, or just so slightly, that you can barely see it. Lock the swash plate lock at this position. You should also have 12-18mm spacing from the top bearing in the swashplate to the bottom of the swashplate lock. That is set at low pitch. This new head is also rpm sensitive in as much as with the 1500 blades, you do not want more than 1500 rpm on the head. With the larger 1600mm blades, you do not want over 1350-1375 rpm. On the Benzin models, your rpm should be around 1300rpm with the proper gear ratio. Set your initial pitch to -2 at low stick, +5 at half stick, and 8 at full stick. This should be a good setting to get you started, and the weight of the heli you are flying will determine the final pitch settings. You also in the setting up phase, want the links to the blade holders on the leading edge. This will allow you to "push up" on the servos for pitch. If you use the offset swash, be sure your radio supports 3 servo 120 CCPM, as this is the only way this swash will work properly. You do not want to manually move the swashplate lock so the rods are at a 45 degree angle from the blade holder. Depending on how long your rods are, they will pop off at certain movements of the swash plate because of the angle. With the rods set on the leading edge, your swash plate should move forward and to the right with a forward movement with the radio stick. Once the static adjustments are done, start the heli. Do not go to hover, but just below hover rpm. Standing in back of the heli, give a small forward input and watch the disc. If it appears to move purely forward, you should be all set. Bring the heli into a hover, and apply small movements checking direction. If the heli wants to move forward and to the left or right also, the swash lock is not in the correct position. Loosen the lock and rotate slightly and retighten, and try again. Only very small movements of the lock are required to make the heli move in a different way, so go slowly. Once set, move the heli around, and get used to the feel of the head. It does fly different than a flybar, but not so much that you cannot get used to it and enjoy this head. C/G is another important factor using this head. You want to be sure that when the heli is lifted by the head, that the back of the skids comes off the ground approximately 15mm prior to the front lifting off. This is without fuel if your tank is in the front, and with fuel if you have the tank behind the main shaft. If you have any questions about this head, feel free to e-mail me.
There always seems to be quite a bit of confusion on setting up the servos for a CCPM installation. It really is not that hard to do. All the radios involved which do a form of CCPM seem to follow the same guidelines, in as much as they have a menu in the radio which will be labeled "Swash Mix" or "Swash Mode". This is where you will choose the form of CCPM you want from the given choices in your radio. Usually, you have a choice of 3 servo 120 degree, or 4 servo 90 degree CCPM. Some of the more exotic radios out there such as the MC-24 will give you more choices, but the above choices are the most popular with the heli's on the market today. If you follow the manual of your given radio for the servo installation on the receiver, things should work fine. What i do after plugging in all the servos is to remove all the servo arms from the servos involved, and install wheels so i can follow the movement of the servos. The first movement you want to get correct is the collective movement of the swash plate. Use the servo reverse function of your radio to get all the servos going in the proper direction for the full collective movement. Once you have done this, you can procede to the other functions. Give a fore/aft cyclic movement to see whether the servos are going the correct way. Most of the time the function will be going backward to what it should be. If this is the case, simply go to the swash menu in the radio, and change the number beside the associated control, and reverse the number. For instance, on a JR radio, it will give a percentage of 60% next to aileron, elevator, and pitch. If the elevator function is wrong when you move the sticks, simply hit the minus key, and take the number down to -60%. This will change the movement of the function, not just one servo like servo reverse does. Do the same thing with the aileron control. Futaba has a default percentage of 50%, while JR radio's have a default of 60%. Both are good places to start, and you can fine tune the percentage during your test flights. Remember that changing the percentage changes the total throw of all the servos involved in that function. You want to keep all your ATV's set at 100%, and not change them as this will change the total throw for just that servo, and you may see differential throw in the movement of the swashplate. Another thing you want to avoid is using sub-trim to center the servos. As this shifts the servo center, it also will shift total throw in one direction or another. With the radio at half stick, rotate a four star arm in order to find the arm which is at 90 degrees to the servo case. Any small adjustments can be to the total length of the rod to the swashplate. Be sure you also have the balls on the servo arms the same distance out from the center of the servo. This will ensure you have the same amount of throw from each servo to the swashplate. As far as servo choices go, any good servo with at least 60 oz. of torque will do the job. Digitals are quite nice, but not needed. I have been using Futaba 9202's for years with no problem. This is on JR radio equiptment. I also make it a point to install the same servo on the throttle as i use to control the head. Reason being is i want the collective and throttle to move at the same speed to help and eliminate eratic throttle to pitch curves. When set up properly, CCPM works real well, but you have to pay attention to details in the setup process. |
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Joe Howard |
