BASIC SET UP for AIRCRAFT USING 2 CHANNELS and 2 SERVOS EACH for AILERONS, ELEVATORS and RUDDER
What lies before you is an attempt to provide a set of written procedures to take you step-by-step through the programming of a typical 30%-40% RC aerobatic aircraft. The programming steps are intended to address the JR PCM 10SX, 10SXII, and 10X radio systems and today's IMAC style of aircraft that utilize 2 channels and servos each for ailerons, elevators and rudder. The Idea was to start at the very beginning with servo installation and linkage set up, and then proceed step-by-step until the basic programming set-up was complete. While in the process of describing some of the basic programming two things became immediately apparent. First was the fact that these radio systems were so rich in useful programming features that it would be difficult to exclude some of them even during basic set up. And second, it is a lot easier to do the actual programming than it is to write about it. On more than one occasion fellow modelers have been overheard saying things like; "This radio has so many features that I don't know where to start learning about them" and "I can't use the manual because I don't know which part to read first" and " I don't know anything about computers so programming is too difficult." Well don't let the thought of programming intimidate you. Do you remember the first time you encountered Cruise Control in an automobile? It had some buttons that were attached to some form of computer. How long was it before you messed around with it and when you got it going you thought, "this is bad, cool, nifty, slick, or maybe even far-out" ­ depending on how long ago it was. Each and every feature in the radio was designed for a specific purpose ­ to help the aircraft fly better, easier, with more precision, faster, and slower... and to make the job easier for the builder, mechanic and pilot. All it takes is some "messing around" and perhaps a little guidance. Try to have some fun with it. Take your time, read and perform the steps below, and if things get terribly messed-up you can just start over and perform the steps as many times as you like. Disclaimer: Owing to the number of variables that exist in each RC aircraft it cannot be guaranteed that these instructions will work for every installation. Therefore the author assumes no responsibility for any outcome including the proper operation of aircraft controls and functions, safety while testing and adjusting parameters, and any other effect that may be associated with the material contained herein. You may mount your servos now and plug them into the channels indicated below or wait until one of the steps below instructs you to do so. However DO NOT ATTACH ANY LINKAGES TO THE SERVOS AT THIS TIME. Plug the servos into the receiver ports as indicated below. SERVO LOCATION Throttle servo Right Aileron servo Right Elevator servo Right Rudder servo Left Aileron servo Left Rudder servo Left Elevator servo RX CHANNEL Channel Channel Channel Channel Channel Channel Channel 1 2 3 4 6 7 8 (Throttle) (Aileron) (Elevator) (Rudder) (Flap, Aux1) (Aux2) (Aux3) TIP: If we plug a DSC or Trainer cord (or just a pin plug with no wires attached) into the DSC receptacle in the back of the transmitter it will turn on the display without transmitting and will enable us to program without running the battery down so quickly.
By Len Alessi 1 All Rights Reserved © 5/24/02 1. Select a Model and Reset all Parameters (settings) It is best to start with a fresh program that has all settings reset to factory defaults. This will ensure that all previous sub trim and trim memory settings are set to zero and that all programmable mixes, dual rates and other special functions are inactive. It will help to ensure the proper set up of all servo linkages/throws and there should be no surprises after set up is complete. a. Select a model using code 84. All programming for this model is going to be erased in the next step. Touch ENTER when you have selected the model memory you want to use. b. RESET the programming for the model by accessing code 28 and touching CLEAR to reset all data for the model. Answer Yes to any questions regarding clearing or resetting the model and touch ENTER when you are finished. We now have a "Fresh" set up to work with. c. As a final step in this process, move all trim levers to their neutral or center positions. 2. Name The Model Lets name the model to help get our fingers limbered-up for programming. a. Access code 81 to select the appropriate letters/characters for the model name. Touch the SEL key to change the selection of characters across the bottom of the display until we see the character we want. Then touch the character. Touching it will move the character to the next position in the model name. The cursor will automatically move one position to the right ready for us to select the next character (the cursor is a pointer that shows us where the next letter is to be inserted -- it only moves to the right and will wrap around to the beginning when it gets to the end). If we want to leave a space, touch the arrow key to move the cursor one position to the right. If we make a mistake and need to replace a letter or want to reposition the cursor just keep touching the arrow key until the cursor gets to where we want it to be and select the character we want. If we need to replace a character with a space, touch the arrow until the cursor is positioned at the character to be replaced, touch SEL until we see a space character at the bottom of the display and then touch the space character. Keep selecting characters until we have the model name completed. Touch ENTER when finished to exit the Model Name function. 3. Set the Wing Type to FLAPERON In order to use two channels/servos for the ailerons we will take advantage of the FLAPERON wing type and its ability to control 2 aileron servos on two separate channels. a. Access the Wing Type function using code 22. b. Touch SEL under NORMAL until FLAPERON appears. Then touch ENTER to exit the Wing Type function 4. Inhibit the FLAP, AUX2 and AUX3 Levers and Switches We need to disable the FLAP, AUX2 and AUX3 levers and switches because we are going to use these channels for primary flight controls (ailerons, elevators and rudder) and we no longer want the levers and switches to control them. a. Access TRIMMER FUNCTIONS or FUNCTION SELECT using code 17. b. For the 10SX owner, touch CLEAR under FLAP, AUX2 and AUX3 until INH appears under each indicating that the levers and switches are inhibited. For the 10SXII and 10X owner, touch SEL under the 1st column that has FLAP in it until the little arrow is next to FLAP. Touch CLEAR to inhibit the FLAP lever. Touch SEL again and the arrow will be next to AUX2 ­ touch CLEAR again to inhibit the AUX2 switch. The arrow should already be next to AUX3 in the 2nd column so just touch CLEAR under the 2nd column to inhibit the AUX3 lever. c. Make sure that FLAP, AUX2 and AUX3 all have INH next to them before touching ENTER to exit the function.
By Len Alessi 2 All Rights Reserved © 5/24/02 5. Set Up A Mixer for Dual Elevator Channels/Servos At this point we will set up a mixer for the elevator channels/servos. For PCM 10SXII and 10X owners this involves only 1 setting because these transmitters have a built-in function to handle dual elevator servos. The PCM 10SX requires programming of a programmable mixer to control two elevator servos on separate channels. By the way, using a separate servo and channel for each control surface has the benefits of providing redundancy; ease of setting both servos to neutral; and the ability to remove any differential throw that may be inherent in the linkages. a. PCM 10SXII and 10X owners, return to the Wing Type function code 22 and touch SEL under TAIL until D/ELEV appears. The radio will now automatically use a built-in mixer to control channels 3 (Elevator) and Aux3 (channel 8) for the elevator servos. We are finished with this step so touch ENTER to exit. b. For PCM 10SX owners select the first programmable mixer using code 51 and continue with the steps in this topic. c. Touch number 3 to set the Elevator as the Master channel and then touch 8 to set channel 8 or Aux3 as the Slave channel. Then touch ENTER to get to the next display. If you make a mistake, touch CLEAR and touch 3 and 8 again before touching ENTER. d. Hold the elevator stick in the up-elevator position and touch and hold the + key until the percentage reads 100%. Now push and hold the elevator stick in the down-elevator position and touch and hold the + key until the percentage reads 100%. e. Touch the PAGE key to get to the next display. f. Touch SEL under MASTER until INLC appears indicating that INCLUDE mixing is activated. INCLUDE mixing tells the mixer to move the left elevator anytime the right elevator moves regardless of where the input is coming from (stick, snap button, another program mix etc.) Always activate INCLUDE mixing when mixing two channels for a primary flight control (Aileron, Elevator, Rudder). g. Now touch SEL under TRIM until ON appears so that the left elevator will move with the right elevator when the elevator trim lever is moved. Always activate TRIM when using multiple channels for a primary flight control. h. Programming of the dual elevator mixer is now complete. Touch ENTER to exit the mixer. 6. Set Up A Programmable Mixer for Dual Rudder Channels/Servos Now we'll set up a programmable mixer for the Dual Rudder channels/servos. a. Access the second programmable mixer using code 52. b. Touch number 4 to set the Rudder as the Master channel and then touch 7 to set channel 7 or Aux2 as the Slave channel. Then touch ENTER to get to the next display. If you make a mistake touch CLEAR and then touch 4 and 7 again before touching ENTER c. Hold the Rudder stick in the right-rudder position and touch and hold the + key until the percentage reads 100%. Now push and hold the rudder stick in the left-rudder position and touch and hold the + key until the other percentage reads 100%. d. Touch the PAGE key to get to the next display (10SXII & 10X owners touch PAGE twice). e. Touch SEL under MASTER until INLC appears indicating that INCLUDE mixing is activated. INCLUDE mixing tells the mixer to move the left rudder servo anytime the right rudder servo moves regardless of where the input is coming from (stick, snap button, another program mix etc.) Always activate INCLUDE mixing when mixing two channels for a primary flight control (Aileron, Elevator, Rudder). f. Touch SEL under TRIM until ON appears so that the left rudder servo will move with the right rudder servo when the rudder trim lever is moved. Always activate TRIM when using multiple channels for a primary flight control. g. Programming of the dual rudder servo mixer is now complete. Touch ENTER to exit the mixer.
By Len Alessi 3 All Rights Reserved © 5/24/02 7. Set Servo Directions For All Channels It is important that all servos move in the proper direction before proceeding with any other programming. Make sure all servos are mounted in their intended locations and plugged into the channels indicated at the beginning of these instructions. Temporarily install an output arm on each servo just for a visual reference ­ there is no need to install the output arm screws yet as they will be moved and repositioned in subsequent steps. The servo arms for both elevators should be pointing in the same direction (both up or down) and the servo arms for the rudder servos should be pointing in the same direction (both up or down). DO NOT ATTACH ANY LINKAGES TO THE SERVOS AT THIS TIME. a. Turn on the transmitter and receiver and access the Reverse Servo function code 11. b. Move the throttle stick from low to high and note the direction of travel relative to the throttle arm on the carburetor. If moving the throttle stick to high will cause the carb to open once the linkage is attached, then it is ok. Otherwise touch 1 on the bottom of the display to reverse the throttle servo direction. c. Move the aileron stick to the Right and note the movement of the Right aileron servo. If the servo movement will cause the Right aileron to deflect upward once the linkage is attached then the right aileron servo direction is ok, if not, touch the 2 at the bottom of the display to reverse the direction of the right aileron servo. Now observe the Left aileron servo when the aileron stick is moved to the Right. If its movement will cause the Left aileron to deflect downward it is ok, otherwise touch 6 at the bottom of the display to reverse the direction of the left aileron servo. d. Move the elevator stick to the Up-elevator position and observe the movement of the Right elevator servo. If its movement will cause the Right elevator half to deflect upward once the linkage is attached it is ok, otherwise touch 3 at the bottom of the display to reverse the direction of the right elevator servo. Move the elevator stick to the Up-elevator position again and observe the Left elevator servo. If its movement will cause the Left elevator to deflect upward then it is ok, otherwise touch 8 at the bottom of the display to reverse the direction of the left elevator servo. e. Move the rudder stick to the Right and note the movement of the Right rudder servo. If the servo movement will cause the rudder to move Right once the linkage is attached then it is ok, otherwise touch the 4 at the bottom of the display to reverse the direction of the right rudder servo. Now observe the Left rudder servo when the rudder stick is moved to the Right. If its movement will cause the rudder to deflect Right it is ok, otherwise touch 7 at the bottom of the display to reverse the direction of the left rudder servo. f. Touch ENTER to exit the servo reversing function. By Len Alessi 4 All Rights Reserved © 5/24/02 8. Set Up and Adjust the Throttle Linkage Now we will set up the throttle linkage and adjust the servo travel for full throttle and idle. Note: Use a non-conductive linkage such as a Ny-Rod if the engine has an ignition system! Using a nonconductive linkage greatly reduces the possibility of interference should the ignition develop a leak. Note: some carbs come equipped with a throttle-stop mechanism (usually an adjustable screw) that can keep the throttle from closing all the way. Either adjust the screw so the carb can be closed tight or remove it altogether as we want the throttle servo to be able to close the carb far enough to stop the engine. a. Turn on the transmitter and receiver and set the throttle stick at 1/2 throttle. b. Move the throttle trim lever to its center detent and install a medium-length servo arm on the throttle servo so that the arm is 90° or perpendicular to the throttle linkage. c. Install the throttle linkage attaching one end to the servo arm (use the hole furthest from the output shaft) and the other end to the carb lever that opens and closes the carb. Adjust the linkage so that the carb is halfway open to correspond to the throttle stick being midway between high and low throttle. Make sure there is no binding whatsoever in the linkage! d. Access the TRAVEL function using code 12. PCM 10X owners should touch the "S" at the top of the display to allow independent adjustment of the high- and low-end travel. e. Move the throttle stick to the full-throttle position and observe the carb and linkage. If the carb is fully open and the servo is buzzing and/or the throttle linkage is bending it is an indication that there is too much travel. If this is the case, touch the "­" key under THRO to decrease the servo travel until the servo stops buzzing and the linkage stops bending. If the carb is not fully open with the stick at high throttle then there is not enough throw. In this case touch the + key Under THRO to increase the travel until the carb is just fully open and no more. If the travel reaches 150% and the carb is still not fully open, then a longer servo arm is required or you must attach the linkage closer to the pivot point at the carb lever. f. Now move the throttle stick to the full-low position and observe the carb and linkage. If the carb is closed tight and the servo is buzzing there is too much throw in this direction. If this is the case, touch the "­" key under THRO until the servo stops buzzing and the carb just begins to open about 1/32". If the carb is not closed within about 1/32" then more throw is required and you must touch the + key under THRO until the carb is just barely open. If you reach 150% travel and the carb is still not within 1/32" of being closed there is probably differential built into the linkage. Try removing the servo arm and rotating it 1 spline towards the low-end travel and readjust the high-end again. If there just isn't enough travel, a longer servo arm is required or the linkage must be attached closer to the pivot point on the carb lever. g. Now move the throttle trim lever to the full-low position. It should completely close the throttle. If there is excessive servo buzzing with the throttle trim at full low, then touch the"­" key under THRO a few more times to reduce the throw a few more percentage points. Note: Once you have finished setting the throws look at the percentages for low- and high-end travel. If they are rather small (less than 60%) you may want to move the linkage inward on the servo arm and perform all adjustments again from the beginning to provide better resolution. h. Final adjustment of the throttle low-end travel should be performed with the engine running and a helper securely holding the aircraft. Start the engine and run it until it gets up to normal operating temperature. i. Access TRAVEL code 12 (10X owners touch S) and position the throttle trim lever in its center detent. If the engine idle gets too low and the engine quits when the trim lever is positioned in the center, touch the "­" key under THRO to reduce the low-end Travel until the engine does not die with the trim in its center detent. j. Making sure the engine stays up to temperature, adjust the low-end travel using the + and ­ keys under THRO until you get the lowest dependable idle with the throttle trim in it's center detent position. This completes the throttle servo adjustment so touch ENTER to exit.
By Len Alessi 5 All Rights Reserved © 5/24/02 SUB TRIM AND MECHANICAL ADVANTAGE
Sub Trims are intended for relatively minor adjustments to servo linkages and not for major trim adjustments to the aircraft. Using excessive sub trim percentages can cause a loss in servo resolution where the servo reaches its travel limit and stops moving before the control stick is fully deflected. The diagram below illustrates an ideal servo/linkage setup when the servo is at neutral (no sub trim or trim offset and digital trims centered). Notice that the servo arm is positioned at 90° or perpendicular to the servo. Also note that the linkage or rod is attached at 90° to both the servo arm and the control surface horn. This setup will result in the same amount of throw in both directions (0 differential throw). If the servo cannot be mounted parallel to the linkage/rod then just make sure the servo arm is at 90° to the control rod when the servo is at neutral. Mechanical Advantage is a very important concept when dealing with larger aircraft. It refers to the leverage that the servo can exert on the control surface. Since the control surfaces are rather large it is important for the servo to have enough mechanical advantage or leverage to control them, regardless of the servo's rated torque. A large amount of torque is of little value if there is not enough leverage to use it. Insufficient leverage can lead to control surface flutter (usually a catastrophic event) and blow-back where the air flow pushes the control surface backwards resulting in mushy or no control at higher speeds. There are two ways to increase the mechanical advantage of the servo. One is to make sure that the control horn device, whether it be a horn as shown in the illustration above or a bolt with a Rocket Citytype fastener, is long enough. The horn is the lever that the servo uses to control the surface. The longer the horn, the more leverage the servo has. It's like a Lug Wrench ­ when you can't get a lug nut loose you put a piece of pipe over the end of the lug wrench to extend the handle and that gives you more leverage to break the lug nut free. It's the same thing - the lug nut is the control surface and you are the servo trying to move it. As a general rule-of-thumb, try to attach the linkage at the control surface so that it is at least 1" away from the surface ­ longer is better. The second way to increase the mechanical advantage for the servo is to attach the linkage at the servo arm as far inward (towards the servo arm retaining screw) as possible while still providing enough throw. It's the "lever thing" again, but in reverse, as we are trying to take leverage away from the control surface by providing it with a shorter lever to work against the servo. Ensure that the attach-point is the same distance from the hinge line for like surfaces (two ailerons, two elevators and two rudder horns). If the attach points are not the same distance from the hinge line there will be unequal throw and it will be more difficult to synchronize the surfaces for equal deflection. This is especially critical for the rudder where two servos are attached to the same surface ­ unequal throw will cause the servos to fight one another causing excessive battery drain, and in severe cases may cause servo damage. Always try to use the maximum amount of Travel (100%-150%) that the radio provides. If it is too much travel don't reduce the percentage of travel in the radio, instead, move the linkage further away from the hinge line at the control surface and/or move the linkage inward on the servo arm or use a shorter arm. If you use high percentages of travel you maintain resolution (fine movements of the stick result in fine positive movements of the control surface). When we decrease travel percentages we lose resolution.
By Len Alessi 6 All Rights Reserved © 5/24/02 9. Set Up and Adjust the Dual Elevator Servos and Linkages The two elevator servos and linkages will be set up so they match one another at center (neutral) and at full deflection up and down. The objective is to first get everything aligned as closely as possible from a mechanical perspective by installing the servo arms correctly and mechanically adjusting the linkages. Only then should the radio settings be adjusted to fine-tune everything. Remember, the excessive use of Sub Trims is to be avoided, as it will result in dead band and a loss in resolution. a. Turn on the transmitter and receiver and make sure the trim levers are centered. It is assumed that all Sub Trims and Trim Offsets are still set to zero as a result of performing the RESET operation at the beginning of these instructions. If you did not perform the RESET operation then set all sub trims to zero using code 15 and reset all Trim Offsets (PCM 10SX and 10SXII only) to zero using code 82 and touching CLEAR under AIL, ELEV and RUDD. b. Install servo arms on the 2 elevator servos so that the arms are at 90° or perpendicular to the servo cases (i.e. straight up or straight down). Rotate, swap and reinstall the arms or try different arms if necessary to get them as close to 90° as you can. It is not unusual for the arms to be tilted slightly and we will fine-tune them in a minute but get them as close as you can for now. c. Access the Sub Trim function code 15 and touch the + and ­ keys under ELEV to adjust the Right elevator servo so its arm is right at 90° to the case (straight up or straight down). d. Touch PAGE to get to the next display of channels and touch the + and ­ keys under AUX3 to adjust the Left elevator servo until its arm is right at 90° to the servo case. e. We now need to set the Right elevator half to 0° incidence in relation to the wing. This can best be accomplished by placing an incidence meter on the wing inboard of the ailerons and blockingup the tail until the wing incidence is at 0°. Now install the linkage for the Right elevator half. Put the incidence meter on the Right stab/elevator and adjust the Right elevator linkage to obtain 0° incidence (or as close to 0° as you can get). Now do the same for the Left stab/elevator and its linkage. f. If zero degrees incidence could not be obtained using the mechanical adjustments, use the SUB TRIM function (code 15) and touch the + and ­ keys under ELEV to adjust the Right elevator servo and touch the + and ­ keys under AUX3 (on the next PAGE) to adjust the Left elevator servo to get both elevator halves at 0°. When finished, both stab/elevator halves should be at 0° incidence relative to one another and to the wing. g. Now its time to adjust the overall travel (up and down) of the two elevator servos. The elevator travel should be set to the maximum that you ever intend to use for precision aerobatic flying. As a general guideline, use as high a percentage of travel as you can (100%-150%) in order to maintain maximum resolution. If a high percentage of travel results in too much throw do not decrease the travel of the servo. Instead, move the linkage outward (away from the hinge line) at the elevators or, move the linkage inward on the servo arm or use a shorter servo arm. This will decrease the throw while increasing resolution and the mechanical advantage of the servo! h. Access the TRAVEL function (code 12). (PCM 10X owners touch S). Hold the elevator stick in the up-elevator position and touch the + and ­ keys under ELEV to set your maximum deflection for the Right elevator half. Do the same while holding the elevator stick in the down-elevator position. Now adjust the travel of the Left elevator by touching PAGE and touching the + and ­ keys under AUX3 to exactly match the travel of the Right elevator in both directions. A degree gauge works well for matching deflections. Dual elevator set up is now complete! NOTE: Once the elevators have been adjusted as described above, use the TRACE RATE function (code 14) to make future adjustments to overall elevator travel. Using TRACE RATE eliminates the need to individually measure/adjust the throws of each servo when more than one channel is used for a primary flight control (Elevator, Aileron, Rudder). It is used to make adjustments only after the channels have been setup for equal throws.
By Len Alessi 7 All Rights Reserved © 5/24/02 10. Set Up and Adjust the Dual Rudder Servos and Linkages The two rudder servos and linkages will be set up so they match one another at center (neutral) and at full deflection left and right. The objective is to first get everything aligned mechanically and then make fine adjustments with the radio. The excessive use of Sub Trims is to be avoided, as it will result in significant dead band and a loss in resolution. It is very important that the servos don't "fight" one another as it may cause excessive battery drain and in severe instances may cause servo damage. a. Turn the transmitter and receiver ON and make sure the rudder trim lever is centered. b. Install servo arms on the 2 rudder servos so that the arms are at 90° or perpendicular to the servo cases (i.e. both straight up or both straight down). Rotate, swap and reinstall the arms or try different arms if necessary to get them as close to this position as you can. c. Access the Sub Trim function code 15 and touch the + and ­ keys under RUDD to adjust the Right rudder servo so its arm is right at 90° to the case. d. Touch PAGE to get to the next display of channels and touch the + and ­ keys under AUX2 to adjust the Left rudder servo until its arm is 90° to the servo case. e. We now need to set the Right rudder servo and linkage center point. Install the linkage for the Right rudder servo and adjust the linkage so that the rudder is straight. If you cannot get it deadon with the linkage, get it as close as you can and then use Sub Trim code 15 and touch + and under RUDD to get it straight. f. Now set the rudder throw in each direction by accessing TRAVEL code 12 (PCM 10X owners touch S) and touching the + and ­ keys under RUDD while holding the rudder stick to the right and then the left to establish the maximum desired throw in each direction. Make sure that the servo is not trying to move the rudder past the physical limitations of hinges and hinge line bevel. Excessive servo buzzing at the end points is an indication of binding and is undesirable. g. Attach the linkage for the Left rudder servo BUT DO NOT MOVE THE RUDDER STICK! Adjust the linkage so that it does not fight the Right rudder servo when the rudder stick is at neutral. Get it as close as you can by mechanically adjusting the linkage. If the servos are buzzing loudly it is an indication that they are fighting one another at neutral. If this is the case, access Sub Trim code 15 and touch PAGE to get to the 2nd page of channels where you can touch the + and ­ keys under AUX2 until the servos are no longer fighting each other ­ it should only take a few percentage points to get them to stop fighting. h. Disconnect the Left rudder servo linkage from the rudder but leave it attached to the servo. Access TRAVEL code 12 and touch PAGE to get to the 2nd page of channels (PCM 10X owners touch S). Now move the rudder stick all the way to the right and hold it there. Pick up the Left rudder servo linkage and hold it up to the attach point at the rudder to see if it needs more or less throw to properly attach and touch the + or ­ key under AUX2 until it looks like the linkage will attach properly. Next move the rudder stick to the Left and adjust AUX2 throw in this direction until it looks like the linkage will attach properly. Get these adjustments as close as you can! i. Attach the Left rudder servo linkage to the rudder. Move the rudder stick all the way to the Right and listen and look for signs of the servos fighting each other. Touch the + and ­ keys under AUX2 until servo buzzing is at a minimum and the servos are not fighting each other. Now move the rudder stick all the way to the Left and repeat the adjustment. Dual rudder servo set up and adjustment is now complete! NOTE: Once the rudder servos have been adjusted as described above, use the TRACE RATE function (code 14) to make future adjustments to overall rudder travel. Using TRACE RATE eliminates the need to individually measure/adjust the throws of each servo when more than one channel is used for the Elevator, Aileron, or Rudder. It is used to make adjustments only after the channels have been setup for equal throws.
By Len Alessi 8 All Rights Reserved © 5/24/02 11. Set Up and Adjust the Aileron Servos and Linkages The two aileron servos and linkages will be set up so they match one another at center (neutral) and at full deflection up and down. The objective is to first get everything aligned mechanically by installing the servo arms correctly and adjusting the linkages. Only then should the radio settings be adjusted to fine-tune everything. The excessive use of Sub Trims (high Sub Trim percentages) is to be avoided, as it will result in significant dead band and a loss in resolution. a. Make sure the aileron trim lever is centered. b. Install servo arms on the 2 aileron servos so that the arms are at 90° or perpendicular to the control rods. Rotate, swap and reinstall the arms or try different arms if necessary to get them as close to this position as you can. c. Access the Sub Trim function code 15 and touch the + and ­ keys under AILE to adjust the Right aileron servo so its arm is right at 90° to the linkage. d. Touch PAGE to get to the next display of channels and touch the + and ­ keys under FLAP to adjust the Left aileron servo until its arm is right at 90° to the linkage. e. Set the ailerons at neutral so that they are in line with the wing root trailing edges. Install the linkages for the both ailerons. Adjust the linkages so that the aileron trailing edges are in line with the trailing edges at the roots of the wings. Get them as close as you can. f. If exact alignment could not be obtained with the mechanical adjustments, use the Sub Trim function code 15 and touch the + and ­ keys under AILE to adjust the Right aileron servo and touch the + and ­ keys under FLAP (touch PAGE to get to the 2nd display) to adjust the Left aileron servo to get both aileron trailing edges aligned with the wing. g. Now its time to adjust the overall travel (up and down) of the two aileron servos. The aileron travel should be set to the maximum that you ever intend to use for precision aerobatics. As a general guideline, use as high a percentage of travel as you can (100%-150%) in order to maintain maximum resolution. If a high percentage of travel results in too much throw then move the linkage inward on the servo arm (closer to the servo arm screw) or use a shorter servo arm, and/or move the linkage outward (away from the hinge line) at the ailerons. Note: Ailerons are large long control surfaces and as such are more prone to flutter than elevators and rudder. It is therefore very important that the linkage set-up provide enough mechanical advantage for the servo to keep the ailerons under control. Mechanical advantage is increased when you attach the linkage closer to the servo screw on the servo arm and when you attach further away from the hinge line at the aileron. As a general rule-of-thumb, try to attach the linkage at the aileron at least 1" from the surface of the aileron and preferably more. If the horns/screws aren't long enough ­ get longer ones! h. Access the TRAVEL function (code 12). (PCM 10X owners touch S). Hold the aileron stick in the full Right-aileron position and touch the + and ­ keys under AILE to set your maximum deflection for the Right aileron. Do the same while holding the aileron stick in the full Leftaileron position. Make sure the deflection is the same in both directions. i. Now adjust the travel of the Left aileron by touching PAGE and touching the + and ­ keys under FLAP to exactly match the travel of the right aileron in both directions. A degree gauge works well for matching deflections. Dual aileron set up and adjustment is now complete! NOTE: Once the ailerons have been adjusted as described above, use the TRACE RATE function (code 14) to make future adjustments to overall aileron travel. Using TRACE RATE eliminates the need to individually measure/adjust the throws of each servo when more than one channel is used for the Elevator, Aileron, or Rudder. It is used to make adjustments only after the channels have been setup for equal throws.
By Len Alessi 9 All Rights Reserved © 5/24/02 12. Setting Dual Rates and Exponential Curves. Dual Rates and Exponential curves can be very effective in setting up an aircraft to "feel" the way you would like it to feel when performing different types of maneuvers. You can essentially change the aircraft's personality just by flipping a switch, causing the aircraft take on traits that make certain maneuvers easier for the pilot. At times you may want the aircraft to feel very crisp such as when performing point rolls and sided-loops and then feel softer for other maneuvers such as rolling circles and consecutive rolls and yet other times when you would like the aircraft to be very crisp but without a the tendency to be over-controlled like in performing snap rolls. Dual Rates and Exponential curves can be combined to produce these traits for most any aircraft. When programming a Dual Rate and Exponential curve always think about what kind of maneuver or flying style you plan to accomplish with it. Dual Rates (D/R) limit how far a control surface travels. Without dual rates your control surfaces deflect to their full travel ­ the travel that you previously established with the TRAVEL function and linkage set-up. When a D/R is programmed it limits the amount of deflection that occurs when the stick is moved to its extremes. For example if you set an elevator D/R to 75% the elevator will only deflect 75% or 3/4 of its full travel, if set to 50% it will be limited to ½ of its full travel and so forth. A D/R setting of 100% results in full travel again as though there were no D/R programmed at all. An example of programming a D/R for the ailerons would be to set up an aileron D/R for flying consecutive rolls by setting the aileron D/R to 25% (actual percentage will vary). At this setting moving the aileron stick full left or full right would result in a roll rate of about 1 roll per second. This allows you to deflect the aileron stick all the way and just hold it there while concentrating on elevator and rudder inputs ­ flying consecutive rolls just became easier. EXPONENTIAL (EXP) does not limit the total deflection of a servo/control surface ­ the surface still moves 100% of its travel. It does however determine how the surface reaches its full travel, or how the control surface moves relative to the stick. When Exponential is not used, the servo response is said to be linear. That is, every movement of the stick causes the same movement in the servo--if the stick moves 20%, the servo moves 20% and the control surface follows the stick throughout the entire travel range. When plotted on a graph where the X-axis (left and right) = stick movement and the Y-axis (up and down) = servo No Exponential movement, the result is a straight line that is at 45 degrees. When using Exponential, a positive (+) exponential percentage causes the servo to move less when the stick is close to the neutral point, and to move more as the stick moves further from the neutral point. For instance, the stick is moved from neutral to 20% and the servo only moves from neutral to 10%. As the stick is moved further from center (from 20% to 40%) the servo moves further and faster (from 10% to 35%) The further the stick is moved away from center, the higher the rate of servo movement. The larger the positive (+) Exponential percentage, the further the stick must be moved from center before the servo rate increases, and the faster the servo rate becomes when it gets close to the end of its travel. When stick travel (left and right) versus servo travel (up and down) is plotted on a graph, the result is a "curve". The curve stays close to the X-axis at the center (small servo movement) and moves away from the X-axis at a greater rate (more servo Exponential movement) as the stick is moved further off center. By Len Alessi 10 All Rights Reserved © 5/24/02 Exponential is typically used to reduce sensitivity or otherwise dampen movements around the neutral stick position without sacrificing full servo travel. This provides the pilot with very smooth and precise control of the aircraft while allowing relatively large movements in the control stick. It becomes easier to make very smooth and precise corrections that are difficult to detect. The PCM 10SX and SXII allow 3 D/R and EXP settings each for Aileron, Elevator and Rudder. The 10X allows 3 D/R & EXP settings when Flight Modes are not activated and up to 5 D/R & EXP settings if all Flight Modes are activated. In our example we will use the POS0 switch positions (switches in the UP position) for normal flying, POS1 (middle switch positions) for snap rolls and POS2 (switches all the way down) for consecutive rolls, slow rolls and rolling circles. If you are already familiar with Dual Rates and Exponential curves and have you own settings in mind, then please feel free to substitute your own settings. It is recommended however that you set rates and curves for each of the 3 switch positions for each control surface. It is also recommended that you use POS0 (switches in the upper position) for normal flying because of some Flight Mode considerations that will be introduced later. NOTE: The percentages provided below are only starting points and serve mostly to convey the concept of Dual Rate and Exponential curves. You will need to test-fly the aircraft using the various switch settings to determine if percentages need to be increased or decreased. a. AILERON D/R & EXP. Access the DR/EXP function 13. The Aileron D/R EXP display appears. If you move the Aileron D/R switch through its 3 positions you will notice the display changing to POS0, POS1 and POS2. b. Position the Aileron D/R switch in its upper position (POS0). We will use this position for normal flying. Decrease the D/R percentage to 75% by touching ­ under D/R. This will limit aileron deflection to ¾ of full travel and set a moderate amount of exponential by touching + under EXP until it is +30%. Touch SEL under TYPE until NORMAL appears to select a normal exponential curve. c. Now put the Aileron switch in the POS1 or middle position. We'll use this position for snap rolls where we want full Aileron deflection and perhaps less exponential so the Ailerons will be more responsive around neutral. Leave the D/R percentage at 100% and set the EXP percentage to +20 by touching + under EXP. Now touch SEL under TYPE until NORMAL appears. d. To set the 3rd Aileron D/R EXP combination for consecutive rolls, slow rolls and rolling circles, set the Aileron D/R switch to its lower or POS2 position. Reduce the Aileron D/R percentage to 25% by touching ­ under D/R to give us a nice slow roll rate. Lets also set the EXP to +30% and set the TYPE to NORMAL. You now have 3 aileron rates/curves defined ­ POS0 (upper position) gives ¾ Aileron travel and moderate exponential for normal flying, POS1 (middle position) provides full Aileron travel and has less Exponential for snap rolls, and POS2 (lower position) has significantly reduced aileron deflection for consecutive rolls and slow rolls. After test flying them, you can come back into D/R EXP code 13 and adjust them by PAGING to the Aileron display, moving the aileron D/R switch in the desired position (POS0, POS1, POS2), and adjusting the D/R and EXP percentages. e. ELEVATOR D/R & EXP. Touch PAGE until the Elevator D/R EXP settings are displayed. Position the Elevator D/R switch in its upper position (POS0). We will use this position for normal flying. Lets leave the D/R percentage at 100% to provide full Elevator travel and set a moderate amount of exponential by touching + under EXP until +30% is obtained. Touch SEL under TYPE until NORMAL appears to select a normal exponential curve.
By Len Alessi 11 All Rights Reserved © 5/24/02 f. Now put the Elevator D/R switch in the POS1 or middle position. We'll use this position for snap rolls where we want to reduce Elevator deflection to help us avoid "burying" the snaps. We also want less exponential so the Elevators will move off center quickly. Decrease the D/R percentage to 50% by touching ­ under D/R. This will limit Elevator deflection to ½ of full travel. Lets also set the EXP percentage to +20 by touching + under EXP. Now touch SEL under TYPE until NORMAL appears. g. To set the 3rd Elevator D/R EXP combination, set the Elevator D/R switch to its lower or POS2 position. Reduce the Elevator D/R percentage to 75% by touching ­ under D/R to give us enough Elevator authority, and lets set the EXP to +45% to give us ultra-smooth control for Elevator input during rolling maneuvers. Touch SEL under TYPE until NORMAL appears to obtain a normal exponential curve. You now have 3 Elevator rates/curves defined ­ POS0 gives full Elevator travel and moderate exponential for normal flying, POS1 has the Elevator travel reduced by ½ and has less Exponential for snap rolls, and POS2 has ¾ deflection and increased exponential for smooth inputs during rolling maneuvers such as consecutive rolls, slow rolls and rolling circles. After test flying them, come back into D/R EXP code 13 and adjust them by PAGING to the Elevator display, moving the Elevator D/R switch in the desired position (POS0, POS1, POS2), and adjusting the D/R and EXP percentages. h. RUDDER D/R & EXP. Touch PAGE until the Rudder D/R EXP settings are displayed. Position the Rudder D/R switch in its upper position (POS0). We will use this position for normal flying. Lets leave the D/R percentage at 100% to provide full Rudder travel and set a moderate amount of exponential by touching + under EXP until +35% is obtained. Touch SEL under TYPE until NORMAL appears to select a normal exponential curve. i. Now put the Rudder D/R switch in the POS1 or middle position. We'll use this position for snap rolls where we want to reduce Rudder deflection to help us avoid "burying" the snaps. We also want less exponential so the Rudder will respond quickly around neutral. Decrease the D/R percentage to 45% by touching ­ under D/R. This will limit Rudder deflection to less than ½ travel. Lets also set the EXP percentage to +25 by touching + under EXP. Now touch SEL under TYPE until NORMAL appears. j. To set the 3rd Rudder D/R EXP combination, set the Rudder D/R switch to its lower or POS2 position. Keep the Rudder D/R percentage at 100% and lets set the EXP to +50% to give us ultra-smooth control for Rudder input during rolling maneuvers. Touch SEL under TYPE until NORMAL appears to obtain a normal exponential curve. You now have 3 Rudder rates/curves defined ­ POS0 (upper position) gives full Rudder travel and moderate exponential for normal flying; POS1 (middle position) has the Rudder travel reduced by more than ½ and has less Exponential for snap rolls; and POS2 (lower position) has full deflection and increased Exponential for smooth inputs during rolling maneuvers such as consecutive rolls, slow rolls and rolling circles. After test flying them, come back into D/R EXP code 13 and adjust them by PAGING to the Rudder display, putting the Rudder D/R switch in the desired position (POS0, POS1, POS2), and adjusting the D/R and EXP percentages. k. D/R EXP Notes. As you touch SEL under TYPE you will notice that there are a number of Exponential types available--NORMAL, EXP/LIN, LIN/EXP, and VTR%. Repeatedly touching SEL under TYPE will cycle through all of the available types. EXP/LIN results in the servo following the stick in an exponential fashion for the first ½ of stick movement and then it switches to a linear progression (straight line) from ½ stick to full stick deflection.
By Len Alessi 12 All Rights Reserved © 5/24/02 LIN/EXP results in the servo following the stick in a linear fashion for the first ½ of stick movement and then it switches to an exponential progression (curved line) from ½ stick to full stick deflection. VTR (Variable Trace Rate) is used in conjunction with Dual Rate and acts like a Double Dual Rate. When VTR is active, servo response follows the Dual Rate response line (smaller percentage gives a flatter line and less movement like a high EXP percentage) until the VTR point is reached (VTR point can be set at 50%, 60%, 70%, 80%, 90%). When the VTR point is reached, the servo rate increases, and the servo follows a higher linear rate. VTR is selected by touching SEL under TYPE until the desired VTR percentage appears. VTR can be used to produce a very versatile response curve. If for instance, an aileron Dual Rate is set relatively low (30%-60%) and the VTR point is set at 70%-90% the resulting response is moderately flat for the majority of travel and then increases dramatically toward the end of the travel. With this type of curve the response is docile around center for slow rolling; crisp in the middle for point rolls; and full at the ends for vertical rolls or crisp rolls at low speed. PCM 10SXII owners have the ability to program 1 customized response curve for each control (Aileron, Elevator, Rudder). The curve is established by setting and moving points just like in programming a multi-point mixer. This feature allows you to tailor the response for both sides of neutral (i.e. one response for up-elevator and a different response for downelevator). If you need a customized response curve and you are not familiar with programming multi-point mixers then wait until you cover multi-point mixing and then return to this section to program a custom response curve. PCM 10X owners have the ability to set different D/R and EXP values in both directions for all 3 switch positions of each control (5 positions if 5 Flight Modes are activated). I.e. different D/R and EXP settings for up-elevator and down-elevator, right- and left-aileron, and right-and left-rudder. Just hold the stick in the desired direction while setting D/R and EXP values for POS0, POS1 and POS2 (and optionally POS3 & POS4) By Len Alessi 13 All Rights Reserved © 5/24/02 13. Set Up Exponential for the Throttle The larger engines typically employ a carburetor such as Walbro, Tillitson and Delorto. In many instances these carbs do not produce a linear throttle response where ¼ throttle stick movement results in ¼ engine RPM. Instead, they will cause engine RPM to increase very rapidly from low thrott