jetss
New User
Posts: 6
Reg: 02-27-08
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 02-27-08 01:22 AM - Post#86449
Hi all,
Doing OK with CX2 so trying the 400. Started with warranty replace main shaft and flybar: both tweaked.
Can,t seem to neutral centre rudder servo- creeps and never seems to stick centre same position twice. Is the gyro to blame?
Grateful for any help. Thanks.
Klaus
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Mike Mas
Full Time Senior Member
Posts: 4127
Loc: Roanoke VA USA
Reg: 02-20-00
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02-27-08 04:50 AM - Post#86450
In response to jetss
It's normal for the rudder servo to act unstable and for the most part, will not return to center unless your in the air. Until the machine is flying where the gyro can sense movement, it will act totally different than the other servos.
Welcome to the Rotory forum!
Mike Mas
"we know around here"
ROTORY ~ THE MOST TRUSTED NAME IN R/C HELICOPTERS
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http://www.rotory.com |
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GMRO
New Member
Posts: 22
Reg: 06-11-03
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02-27-08 06:31 PM - Post#86454
In response to Mike Mas
Hi Klaus,
Make sure you allow the gyro to complete its boot up. Don't move or bump the heli once you connect the battery pack up until you see the LED on the gyro light up. If you bump it just unplug and start over.
If you bump the gyro while it boots up you will see strange t/r servo movements. The t/r servo will go to full throw on its own rather quickly. No subtrim or rudder trim will fix that. So just reboot it and you will see a more neutralized slower creeping t/r servo.
As Mike pointed out with Heading Hold gyros it is normal for the servo to creep a little until it reaches the end of travel while you have the heli on the bench. It will not be this way in the air. The stock TX offers 2 different gain values as you flip the switch. From the factory both put the GYRO in HH mode so don't be alarmed if you see the t/r still creep no matter what position that switch is in. One is just a little less gain.
Hope this helps. Welcome and good luck!
_____________
Best Regards,
Ron Osinski
aka - GMRO
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jetss
New User
Posts: 6
Reg: 02-27-08
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 Re: servo creep
02-27-08 11:32 PM - Post#86456
In response to GMRO
First of, thanks for feed-back and warm welcome.
Seems I've commited an major OH OH. Had it all apart last night AFTER noticing t/r slider butting hard against t/r case and t/r hub making t/r pushrod bow. Not even sure servo arm is back on in correct position.
Adjusted t/r travel to 15% r/h and 40% l/h to avoid hard stops but r/h travel now dead slow.
Sohh; thinking I need to start from beginning but nothing in manual to help out. Is there some place to find this info? Thanks again for any help!
Klaus
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GMRO
New Member
Posts: 22
Reg: 06-11-03
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Re: servo creep
02-28-08 05:04 PM - Post#86460
In response to jetss
Here is a start.
With TX ON only:
Put TX rudder travel adjust at 60 on both left and right stick adjustments.
Gyro Menu shows gain at 64 on 1 switch position and maybe 60 or so on the other position as you flip the gear/gain switch. Next look at your rudder digital trim lever and make sure you are at ZERO with the hash mark in then center on the TX screen. Flip to ID stunt mode and check then HOLD as well. Make sure the hash mark is centered on the screen when you flip into these modes.
Next go into sub trim and make sure the rudder channel has NO sub trim number. Shut off TX.
Remove plug of t/r servo plug from the gyro. Go to channel 4 of your receiver and unplug gyro and plug in the rudder servo along. Now turn on TX and plug in heli. You may want to disconnect the motor to be safer...your choice. With the rudder stick centered look at servo horn on servo. Move the rudder stick to see servo move. You can check for binding this way and check for the center. I recommend that you put the servo horn on the servo with the horn facing SLIGHTLY forward. You could put it at perfect 12o'clock with the TX stick centered but you will likely see binding if you move the rudder stick. Advance the servo horn 1 tooth or slightly forward to put the horn say at 11o'clock vs. the 12 for perfect vertical. Now with TX still on and rudder servo horn at this slightly advanced location look at your t/r pitch slider at the rear of the heli. Adjust your t/r rod length so the SLIDER on the t/r output shaft is almost centered as it travels on the shaft. You may need to lengthen or shorten the rod. OK not a problem just remember to have the TX on and your servo horn in the slightly advanced position.
Now shut off the heli. Reconnect the gyro to channel 4 then the servo to the gyro.
Make sure to reconnect your motor if you disabled it.
You should be very close to now have a good flying tailrotor on the B400. You may need to adjust your gain a little but it should be very close. ALSO if you notice the t/r servo creeps a little you could NOW go into the sub trim for the rudder channel and add a few numbers to help stop it. I usually HOVER the heli and make this adjustment. IF you add a number and the servo moves faster you went the wrong way...remove the number and add some the other way. Same as if you hover...if it moves/yaws more...take the number off and go the other way.
You could use the rudder trim but that is not as fine an adjustment as sub trim. PLUS sub trim work in all flight modes where as rudder trim is separate...so you'd have to adjust your rudder trim lever in each mode...normal - id - hold. Your choice.
GOOD LUCK!
____________
Best Regards,
Ron Osinski
aka - GMRO
Edited by GMRO on 02-28-08 05:05 PM. Reason for edit: No reason given.
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jetss
New User
Posts: 6
Reg: 02-27-08
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 02-29-08 12:01 AM - Post#86463
In response to GMRO
Hello Ron,
Very grateful for your excellent reply! Very helpful. Not sure about the "normal-ID-hold" you make reference to; would that be the GEAR/F.MODE toggle on T/X?
Seems to have gone perfectly till gyro put back in setup. Servo still creeps; best overall with SUBTRIM set to 8 R/H rudder.
Is there a way to disable head hold and use basic gyro function just to see if that stops creep? Thinking to take to hobby shop and let owner try flying it.
Again Ron many many Thanks. Klaus
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GMRO
New Member
Posts: 22
Reg: 06-11-03
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02-29-08 02:36 PM - Post#86466
In response to jetss
Hi Klaus,
The modes I referred to are Normal mode...where no switch is active. On left side of the TX you have an IDLE UP mode switch. Not on face of TX it is on the surface of the TX where the antenna exits the TX. Left side...long lever switch. That is your Idle UP switch. If the switch is in the AWAY position you are in normal mode. So you have a rudder trim for that mode. If you flip the ID switch you now have another rudder trim you can set.
If you look at the right side of the TX...same surface as ID switch...you will see a HOLD switch. This shuts off the motor for autorotations. If you flip that switch the motor should not operate if you move the throttle/collective "T/C" stick. So flip that switch and you have a rudder trim there too. That is what I mean when I say the 3 modes...normal/ID/HOLD...3 separate rudder trims to set. If you use SUBTRIM it carries into ALL 3 of these flight modes. So you don't have to rudder trim separately. You can check this but leave the heli off as you flip the switches to check this or the motor may come alive.
The subtrim number you mention is fine. It is quite acceptable to have 2 to 10 as the number. Subtrim numbers are very small fine adjustments...vs. the rudder trim usage. So you are well within acceptable numbers.
You could put the gyro into standard rate mode...but that will cause yaw of the heli. That is IF you centered the t/r pitch slider with the linkage as I suggested above. This set up is for heading hold which is what the gyro and TX program is the set default. If you put the gyro into std mode the heli WILL yaw a bit. Servo will not creep but the heli t/r linkage will need adjusted for std mode.
You can go into your gyro menu and change the gyro values to lower numbers to change it. I've not played with the gyro in that mode so I cannot provide numbers. Check your manual for reference. Basically lower the gyro numbers in the gyro menu to put the gyro in standard rate mode. If at 60 now...go much lower. What you want to see is the servo go to the center position. BUT before you do that check you set up now. Move the rudder stick to full deflection then release it. You should see the t/r servo go to the full throw and not return to center. Once you get the gain number right for std mode you will see IF the rudder stick is moved to full throw and released that the servo springs back to the center position. It will do this each time consistently. This is how you will know you have the STD rate mode set up for the gyro. If the servo sort of stays at the full end throw position you are still in heading hold mode. SO you can adjust that menu number till you see the servo go to center...this would be the same position you saw when you removed the gyro from the servo in the previous post to check the servo horn location.
REMEMBER, if you try to fly in std rate mode your t/r linkage WILL need to be adjusted to keep the heli from yawing. This is because the gyro is NOT making the corrections and the t/r trim is off. So a mechanical rod length adjustment will be required for std rate mode…quite normal.
I'd say stay with heading hold. It is easier. Seeing the servo creep is not an issue. Hovering the heli will show it will be fine. Again I don't look at the bench activity of the servo much. Just for that basic servo horn set up. Past that hover the heli and use the subtrim to remove any yawing. It will work.
GOOD LUCK!
____________
Best Regards,
Ron Osinski
aka - GMRO
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Mike Mas
Full Time Senior Member
Posts: 4127
Loc: Roanoke VA USA
Reg: 02-20-00
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02-29-08 06:13 PM - Post#86467
In response to GMRO
As always Ron - thanks for some great posts!
Mike Mas
"we know around here"
ROTORY ~ THE MOST TRUSTED NAME IN R/C HELICOPTERS
Get Your Free Issue of Rotory
http://www.rotory.com |
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jetss
New User
Posts: 6
Reg: 02-27-08
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 03-01-08 02:06 AM - Post#86472
In response to Mike Mas
Ron,
THANK YOU for helping me get on track and educating my 25 watt lightbulb. She's now 100w and burning bright!
Not withstanding, still MUCH to learn but T/X manual "gyro" section making lots more sense now thanks to your willingness to answer my NEWBIE questions.
Can't wait to see Hobby shop owner take it for a spin after the repairs and re-rigging. Once again I really appreciate your time and help.
Klaus
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