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HomeRC & PowerAircraftHelicopterRadio - Futaba FASST › New 8fg owner, 3 quesitons
04-29-2010 07:26 PM  8 years agoPost 1
flyinfriend

rrApprentice

North American continent

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Hi,

Three quick questions:

How do the two functions of neutral point and sub-trim differ in their use? I have always used sub-trim to get the horn to 90 degrees. Are you supposed to use the neutral set function in the 8fg instead? It has both functions hence my confusion.

I usually use epa/atv to adjust out high and low swash leveling after setting up mid-stick as level using link adjusting. With the 8fg are you supposed to use the same method?

Last question, what is the difference between Servo travel adjustment and Limit point adjustment. I searched here and read the hits and I still don't understand when one is used versus the other.

Thank you for any help,

Tom

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04-30-2010 02:05 AM  8 years agoPost 2
hornet dave

rrKey Veteran

Cedar Rapids, IA USA

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Lets see...

I'm assuming you're talking about the neutral point function on the swash setup screen. It is used to tell the tx where exactly along the collective stick movement that you will be setting all your ccpm bellcranks at 90 degrees. Typically this is at mid stick and zero pitch, but if you choose something different you must tell the tx so it can make adjustments.

If you are doing a typical 0 degree setup at midstick, you will not adjust the neutral point, and you will mechanically get the servo arms as close to 90 degrees as you can and use subtrim to make any fine adjustments to get the servo horns correct.

For the CCPM setup, do NOT adjust the servo EPA's. Leave them all at 100%. Use the swash setup screens to mix out all your interactions.

Regarding servo travel adjustments, here's what happens. Mixes, dual rates, etc, can over-drive a servo so it goes past it's end point setting. However, the TX will never allow a servo to go past it's limit setting. It doesn't become an issue very much, but it's handy to use the limit setting to keep carburetors from hitting its stops, etc. So in most cases, adjust the end point as you usually would, and only worry about the limit if you absolutely don't want something to bind and you have some sort of crazy mixing or something that could cause it to over-drive the servo past it's end point.

I got a fever! The only prescription is MORE 6HV

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04-30-2010 02:59 AM  8 years agoPost 3
flyinfriend

rrApprentice

North American continent

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Thanks hornet dave!

Thank you for the neutral point explanation I understand that now!

Regarding the servo travel limit. On my gasser this should allow me to limit the servo travel on my throttle arm (the throw range on the gasser carb is much smaller than the throw range on the nitro )and leave the epa on that channel at 100-100 which is what the governor likes to see. Then I can set my throttle curve as I normally would 0-10-12-18-65 for my gasser normal throttle curve and 65-18-12-18-65 for idle up(I set back-up throttle curves in case of gov failure).

Thanks again,

Tom

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04-30-2010 03:36 AM  8 years agoPost 4
alexf1852

rrApprentice

Inverness, FL - U.S.

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I'm not familiar with all the swash mix settings. So I just leveled my swash at mid stick using sub-trim. And leveled at high and low stick using the end points. My servo arms were not near 90 so I had to use a significant amount of sub-trim.

Anyone have a good tutorial on how to use the swash mix settings to level the swash at all 3 positions?

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04-30-2010 03:51 AM  8 years agoPost 5
hornet dave

rrKey Veteran

Cedar Rapids, IA USA

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Copied from here on RR:

<<Works for the 12FG as well; some info may be on the second "page" of a given screen, but it's all there.>>

eCCPM/Swash Detail Set Up with the 14 MZ - Step by step guide
Courtesy of Ben Minor

Preface: Before any of the advantages that the 14MZ radio affords the modeler with an eCCPM model can be realized, a sound mechanical set up must first be obtained. The radii of all servo wheels must be identical. All servos driving the swashplate must be of the same type. It is preferable to start with either new servos or at least a set with relatively low and equal time on them. This practice ensures a reasonable degree of matching between each of the servos driving the swashplate and thus helps to minimize control interactions.

Set Up Steps:

1.Enter the SERVO MONITOR menu under LINKAGE. Select NEUTRAL TEST and turn it on. This locks the model's servo in exact neutral, which is vital to eCCPM set up. Under the ATV and Subtrim menus, all values for the servos/channels driving the swashplate should be set to 100% (ATV), 155% (LIMIT for ATV), and ZERO for Subtrim.

2.Locate the mounting point for each ball link on the servo driving the swashplate at EXACTLY ninety degrees relatively to horizontal. Theoretically, this should be ninety degrees to the long axis of the servo's case. In achieving this geometry, the use of subtrim should be avoided if at all possible.
3.Adjust the pushrods going from the swashplate control servos to the bellcranks (if present on the model) so that the bellcranks are exactly square and perpendicular.

4.Adjust the pushrods going from the bellcranks to the swashplate so the swashplate is EXACTLY level and square to the models mainshaft from all orientations. At this point, set the desired half stick collective pitch in the rotor blades. For a 3D model, this will be ZERO degrees. For a contest model, the center stick position may be plus a few degrees depending on pilot preference.

5.Going back to the SERVO MONITOR menu, turn off the NEUTRAL test function. Within LINKAGE screen, enter the SWASH menu. There you will see NEUTRAL POINT and SWASH AFR.

Under usual circumstances, the NEUTRAL POINT menu will not need to be manipulated. Per your model manufacturer's recommendations or your own preferences, set the AILERON SWASH AFR for the MAXIMUM desired amount of aileron cyclic (roll) pitch. 6-7 degrees is a good starting point. Repeat this for the ELEVATOR SWASH AFR. 6-7 degrees is a good starting point here as well. The PITCH AFR sets the TOTAL number of degrees of collective pitch range that the model has. For most models, the total range should be between 20-22 degrees of total pitch.

6.Touch the SWASH DETAIL button in the top right-hand corner of the screen. Move the collective stick up and down and note how the boxes on the various mixing function alternately become highlighted. When a box goes white, it is open for adjustment.

7.Place the collective stick at maximum pitch. Adjust the highlighted box under PIT to AIL until the swash sits level WHEN VIEWED FROM THE FRONT OR BACK OF THE MODEL. Lower the collective stick fully. Using the now highlighted box next to the one that you just adjusted, repeat the procedure once again viewing the model from either the front or rear.

8.Return the collective stick to maximum. Adjust the highlighted PIT to ELE box until the swash sits perfectly level WHEN VIEWED FROM EITHER SIDE OF THE MODEL. Lower the collective stick fully as before and repeat this procedure for the now highlighted box, once again adjusting for a level swash when viewed from the side of the model.

9.Position the collective stick to half. Move the elevator back and forth and watch as the ELE to PIT adjustment boxes in the MIXING RATE area flash back and forth. Also note the center pivot ball of the swashplate is likely moving up and down a bit as you apply the fore and aft elevator command. Adjust the highlighted box in the ELE to PIT menu so the fore and aft elevator commands do NOT cause the swashplate's center pivot ball to move up and down.

The AIL to PIT adjustments can be found to flash back and forth as left or right aileron commands are input. The collective stick should still be at half. Similar to the way the swashplate's center pivot ball moved up and down with elevator commands, left and right aileron commands may cause the same movement. After determining which adjustment box corresponds to left and right, adjust each as needed until the swashplate's center pivot ball no long rises and/or falls with an aileron command.

After adjusting the ELE to PIT and AIL to PIT functions, the swashplate's center ball should remain more or less still when aileron or elevator commands are input at the half collective stick position.

10.The final MIXING RATE function to adjust is the ELE to AIL. With the collective stick still at half, move the elevator stick back and forth while viewing the model from the front or rear. The goal here is to have the swash remain level as to tilts back and forth with the elevator command. By nature, it is more difficult to tell if the swash is tilting left or right with the elevator commands. Here is a tip to help make the tilt, if present, more visible. Rotate your model's rotorhead so the flybar is oriented EXACTLY parallel to the tail boom. Repeat the up and down elevator commands. If you note the flybar paddles moving as the elevator commands are input, then the swashplate is also tilting left and right. Adjust either one or both of the ELE to AIL adjustment boxes until the flybar paddles remain more or less motionless while elevator commands are input. Again, it is VERY important that the flybar be oriented exactly parallel to the tail boom for procedure to be accurate.

In simplest terms, the LINKAGE COMPENSATION functions are used to adjust out interactions that occur at high and low collective ranges. Place the collective stick at maximum. Move the aileron control left and right and note the way the swashplate's center pivot ball moves up and down. Adjust the boxes corresponding to left and right aileron commands under AILERON until the swashplate's center pivot ball sits more or less motionless when left and right aileron commands are input. Repeat this same procedure for the aileron commands when the collective stick is at full low. You may need to play around with the values in multiples greater than one until you get things close, then go one percent at a time until you get it just right. The radio will allow you to get things just about perfect, so be patient.

The ELEVATOR adjustments under LINKAGE COMPENSATION work exactly as they did for aileron, except here you adjust the highlighted boxes as needed until your swashplate's center pivot ball sits more or less motionless at full high or low collective stick positions when elevator commands are input. When the AILERON and ELEVATOR commands under LINKAGE COMPENSATION are correctly adjusted, your swashplate's center pivot ball will remain basically still at high or low collective positions as you apply aileron and/or elevator commands.

The last swashplate tuning feature to adjust is the SPEED COMPENSATION. This feature adjusts out interactions inherent to 120 degree eCCPM when RAPID elevator commands are input. A good starting value is 15%. Adjust this percentage up or down until your swashplate's center pivot ball stays more or less still as you cycle the elevator stick back and forth. Try to move the stick back and forth at some reasonably realistic and consistent rate to most accurately fine tune this adjustment.

Ben Minor

MRC Hirobo Helicopters Team Futaba Castle Creations
Morgan Fuels Esprit Models ProgressiveRC

I got a fever! The only prescription is MORE 6HV

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