servo travel range is abt 90 degrees normal? GY401 & S9257

[kaon]

Hi all,
I'm a beginner setting up a MiniTitan.

Just want to check if the following is normal:

With power off, using my fingers to rotate the S9257 servo, the travel range feels normal, a bit more than 180 degrees.

However when the S9257 is powered up, thru the GY401, via the AR7000 Rx, full-rudder left and right command from the Tx makes a servo movement of only about 90-100 degrees, even when the "LIMIT" trimmer is set to 140 (max).
And I have not set any travel limits on the Tx yet.
Is this normal? Why?

BTW, I find that "LIMIT" trimmer set a bit under 80 makes the servo exercise the tail fully without binding. This is with the MiniTitan manual recommended horn length of 10.5mm.

Does all this sound correct?

According to the GY401 manual, I should issue full-left, full-right rudder stick to find the extents of movement and use the "LIMIT" trimmer to prevent binding. Implying that the GY401 itself will never command the gyro to travel even more than what the stick commands. This is what I understand...

[Murdanny]

Hi all,
I'm a beginner setting up a MiniTitan.

Just want to check if the following is normal:

With power off, using my fingers to rotate the S9257 servo, the travel range feels normal, a bit more than 180 degrees.

However when the S9257 is powered up, thru the GY401, via the AR7000 Rx, full-rudder left and right command from the Tx makes a servo movement of only about 90-100 degrees, even when the "LIMIT" trimmer is set to 140 (max).
And I have not set any travel limits on the Tx yet.
Is this normal? Why?

BTW, I find that "LIMIT" trimmer set a bit under 80 makes the servo exercise the tail fully without binding. This is with the MiniTitan manual recommended horn length of 10.5mm.

Does all this sound correct?

According to the GY401 manual, I should issue full-left, full-right rudder stick to find the extents of movement and use the "LIMIT" trimmer to prevent binding. Implying that the GY401 itself will never command the gyro to travel even more than what the stick commands. This is what I understand...

is your servo center?

[kaon]

is your servo center?

Approximately, yes.
Do you have GY401 & S9257?
Is what I described abnormal?

[remotemadness]

hi bro,

401 and 9257 is good.. so no worries..

i'm not sure if its normal for the servo to travel so much without power up..

in your set up the important thing is to have your servo set to dead center..

1. servo horn center to servo.. (plug in to channel 4 without going thru gyro.. or switch to rate mode to find center.. can use a bit of subtrim to do this)
2. adjust tail pitch slider center to rod..( you can adjust this by shifting the servo mount up and down the the boom)

3. you mention about the 10.5mm out of the servo arm..( this is to make use of the servo max effective travel range without binding) so that when you dial in your limit.. you dial in equal amount on both side of travel...

4. plug in servo to gyro.. gyro to rx and test the gyro sense.. make sure its sensing the correct side when you move your rudder stick.. here you have 2 place to adjust (from your tx SERVO REV function)(and on your gyro)

5. test hoover to set the gain... 401 advice is to set at 70%...

hope this help..

once you are familiar with it.. all gyro works the same.. just with different brand.... slight diff in setting

[nacar]

As long as your servo arm has been set 90 degree, and the tail pitch slider can travel it's full left and right range, it's OK.

[Murdanny]

hi bro,

401 and 9257 is good.. so no worries..

i'm not sure if its normal for the servo to travel so much without power up..

in your set up the important thing is to have your servo set to dead center..

1. servo horn center to servo.. (plug in to channel 4 without going thru gyro.. or switch to rate mode to find center.. can use a bit of subtrim to do this)
2. adjust tail pitch slider center to rod..( you can adjust this by shifting the servo mount up and down the the boom)

3. you mention about the 10.5mm out of the servo arm..( this is to make use of the servo max effective travel range without binding) so that when you dial in your limit.. you dial in equal amount on both side of travel...

4. plug in servo to gyro.. gyro to rx and test the gyro sense.. make sure its sensing the correct side when you move your rudder stick.. here you have 2 place to adjust (from your tx SERVO REV function)(and on your gyro)

5. test hoover to set the gain... 401 advice is to set at 70%...

hope this help..

once you are familiar with it.. all gyro works the same.. just with different brand.... slight diff in setting

i think 401 and 9257 you only need less than 40%. Im on 38% and my beam hunts like nothing. 70% is overdose unless flying big heli.

[kaon]

hi bro,
401 and 9257 is good.. so no worries..
i'm not sure if its normal for the servo to travel so much without power up..

Ok... well this is easy to verify by manually twisting the horns to the mechanical stops, with power off... Anyone?
For mine, it is the normal ~190 degrees of travel. And yet when powered, the travel is only about 90 degrees, centered around the center.
It is not causing problems, I just found it curious. It may be this way by design.

in your set up the important thing is to have your servo set to dead center..

1. servo horn center to servo.. (plug in to channel 4 without going thru gyro.. or switch to rate mode to find center.. can use a bit of subtrim to do this)
2. adjust tail pitch slider center to rod..( you can adjust this by shifting the servo mount up and down the the boom)

3. you mention about the 10.5mm out of the servo arm..( this is to make use of the servo max effective travel range without binding) so that when you dial in your limit.. you dial in equal amount on both side of travel...

4. plug in servo to gyro.. gyro to rx and test the gyro sense.. make sure its sensing the correct side when you move your rudder stick.. here you have 2 place to adjust (from your tx SERVO REV function)(and on your gyro)

5. test hoover to set the gain... 401 advice is to set at 70%...

hope this help..

once you are familiar with it.. all gyro works the same.. just with different brand.... slight diff in setting

OK thanks for the tips.

I read something about quickly toggling between rate-mode and HH-mode (3 times in 1 second) to make tell the gyro to command center position, for set up purposes.

[remotemadness]

i think 401 and 9257 you only need less than 40%. Im on 38% and my beam hunts like nothing. 70% is overdose unless flying big heli.

i suppost... its maybe I'm using a 6 channel rx.. no gear switch.. from the 401gain swtich its close to 70%..

[kaon]

I read something about quickly toggling between rate-mode and HH-mode (3 times in 1 second) to make tell the gyro to command center position, for set up purposes.

Correction, the above makes tells the gyro to update its memory of neutral rudder stick signal.
Left-Right rudder stick 3 times quickly in HH mode makes the servo go to neutral, but it doesn't seem to work for me... better to just switch to rate mode (aka "normal" mode).

Two other things I have noticed:

1. When in rate mode, rudder stick at only half-left and half-right causes the gyro to go to the ends of its travel. Maybe this has something to do with the model being stationery.

2. I tried connecting the S9257 directly to the AR7000, and its travel is still only about 90 degrees, with no subtrims or limits on my Tx. Again, this may not be a problem... just weird, wondering if someone can confirm this is normal.

[remotemadness]

i think its normal to only have that amount of travel.. give and take a few degree EPA.. i think its just a cussion they make servo mechanical travel to have 180 degree.. but normally you dont need that amount of travel.. it will start to bind the head.. you'll find that you have to dial down servo travel..

Correction, the above makes tells the gyro to update its memory of neutral rudder stick signal.
Left-Right rudder stick 3 times quickly in HH mode makes the servo go to neutral, but it doesn't seem to work for me... better to just switch to rate mode (aka "normal" mode).

Two other things I have noticed:

1. When in rate mode, rudder stick at only half-left and half-right causes the gyro to go to the ends of its travel. Maybe this has something to do with the model being stationery.

2. I tried connecting the S9257 directly to the AR7000, and its travel is still only about 90 degrees, with no subtrims or limits on my Tx. Again, this may not be a problem... just weird, wondering if someone can confirm this is normal.

[khatiban]

2. I tried connecting the S9257 directly to the AR7000, and its travel is still only about 90 degrees, with no subtrims or limits on my Tx. Again, this may not be a problem... just weird, wondering if someone can confirm this is normal.

Most servo travel are mechanically limited to about 180deg (plus-minus
20deg?)

Analog servos will follow Tx command blindly until they hit
mechanical limits and probably overheat and burn its circuits eventually.

Digital servos, on the other hand, usually have its own
pre-programmed end point. These software-controlled limits are programmed
right into the servo itself and they are independent of the Rx commands
coming from the Tx.

For example, if a digital servo is programmed to limit its travel between
-45deg and +45deg, the servo will stop moving further once it reaches the
limit (in this case, + or -45deg) even if your Tx commands the servo
to move further (e.g. +50deg)

NOTE:
This technology is not available in all brands/models of digital servos.
Do not assume. Be sure. Always check.

[kaon]

Analog servos will follow Tx command blindly until they hit
mechanical limits and probably overheat and burn its circuits eventually.

Digital servos, on the other hand, usually have its own
pre-programmed end point. These software-controlled limits are programmed
right into the servo itself and they are independent of the Rx commands
coming from the Tx.

For example, if a digital servo is programmed to limit its travel between
-45deg and +45deg, the servo will stop moving further once it reaches the
limit (in this case, + or -45deg) even if your Tx commands the servo
to move further (e.g. +50deg)

I see. Thanks.

[kaon]

update

Brought my MiniTitan to RCS today for general assembly check. Lots to learn from Ken.
For the tail servo, he moved the ball from the recommended 10.5mm horn position, inwards to the innermost hole, 8.5mm.
Seems to work OK.

I am using Spektrum DX7, and I currently use AUX2 with "Travel Adjust", for choosing gyro mode and sensitivity. I slowly increased gain up to the max with not much difference, "+150%" for HH and "-150%" for rate.

In HH mode, there is a very slow counter-clockwise yaw. Even at max gain, mostly no hunting except just before it takes off, not sure if that's vibration or caused by gyro. Sudden increase in collective dues cause tail to yaw clockwise by abt 30 degrees before gyro catches up.

In rate mode, I'm happy to have adjusted servo-on-boom position till quite perfect.