Gy401/S9257 - tail swinging

[hfl]

Due to having 4 new Turnigy 2650 20/30C-lipos, getting trouble with my tail.
It´s swinging during figures like flips or loops, even more during climbs.
Always when power is needed.
With my 2x3s zippyHs I didn´t have that. Maybe the lipos are stronger than my older 2 x 3s packages.
Decreasing sense doesn´t help a little, but the tail becomes sluggish then.

Some people guess to changing tail servo to 9254 instead of 9257.
But the 9257 normally is a servo for 500 class helis. As Trex 500 came out it was THAT servo for the tail.

The servo arm distance is 13,5mm, changing it to 10,5mm and looking for a new try.

Does anyone make similair expierience with that combi mentioned above ?



hfl

[Tail boom]

Hi,

Which gyro are you using?

I had quite some challenges getting the Spartan and 3500G working without occassional tail wags or shudders.

Found out that the default deceleration setting on the Spartan is too high for 500 class helis.

Right now I am at:

Spartan w/ 3500G, ball on 13 mm
Gear channel setting at 33% (true gyro gain is around 23% +/-, need to check again)
Deceleration at 60%
Head speed around 2750 rpm
Stock motor with 14T

Works now.

Best,
Frank

[JustPlaneChris]

Title says he's using a GY401.

Decreasing 'sense' (gain?) is the opposite of what you want to do. Increase the gain, and the tail swings with power should lessen. If you get a fast wagging, the gain is too high.

[hfl]

Onto My Radio (Spectrum Dx6i) the % with gyro setup menu runs from 0 to 100.
0-50% is Normal Mode of the gyro, 51-100 is HH mode.
I am only using HH mode. the percentage is set to 73%.
Lowering that value makes the tail become somewhat unexact, but wagging gets less or disappears. No good setup to me. Increasing that value makes the tail more wagging or swinging, not a goog choice, too.

I tried out the setup with 10,5mm ball- to- center of the screw-distance, former 13,5mm as said by the Protos manual and its better now.
With the value of 75% it seems to be ok. This 10,5mm are also advised in the Gy401-manual as the largest distance to use.

Head speed is somewhat about 2500 rpms. The complete setup is not easy to handle due to using different lipos with diff. age and power.

I am using that lipos described at the beginning of the thread.



hfl

[Tail boom]

Hi,

Try the following:

On the DX6i set the rudder end points left and right to maximum (I think 125%). Set rudder dual rate to 100%. All rudder trims and sub-trims to 0. Set the rudder ball back to 13.5 mm. Set the delay on the gyro to 0. Set the servo mode on the gyro to digital. Set the travel range on the gyro to 100 initially. Switch to rate mode and adjust the tail linkage so that the tail pitch slider/fork is 90 deg to the tail shaft (in that position your tail blades should have approx. 8 deg of pitch, i.e., the slider/fork should sit rather a little bit to the left of the middle of the tail shaft). Make sure your servo horn sits in a 90 deg angle to the tail push rod when in the rudder neutral position (i.e., tail pitch at 8 deg). Then adjust the travel on your gyro so that the slider does not bind in the farmost left position.

Switch to heading hold and fly, and go up with your gain until you have a wagging tail (e.g., upon hard and short tail rudder inputs). Then back off a few gain points.

Should work.

Let us know.

P.S.: Make sure there is no binding in the tail linkage while you have the tail push rod off the servo.

Best,
Frank

[mosh1]

I had tail blow out issues on very windy or fast backwards hard flying until I totally reamed all ball links in the tail. I thought it was smooth enough but apparently not. There has to be NO binding or stickiness at all pushing on the pushrod when disconnected from the servo. Once that was done, the tail held awesome. Using a Spartan gyro with stock settings.

[hfl]

I´ve tried out the suggestions tailboom made refering to the tail setup.
There is no success at all. The tail is wagging during stronger pitch inputs and coming out of loops the tail shatters mostly. The only I can doing is decreasing my gain.
But the tail becomes sluggish then. Head speed is about 2650 rpm.
With weaker lipos this setup does work, but the head speed is about more than 200rpms smaller. I cannot take that as my basics.
All that with a ball distance of 13,5mm. Switching back a hole (10,5mm) it´s seems quite good.


So my resume can be that
1. the Gy401 is not able to handle that 13,5mm arm.
2. the tail servo S9257 is too weak or too slow or both.


Should I try a stronger servo like the Futaba 9254 ?


hfl

[dizzymarkus]

Im far from a pro and all I can do is tell you my side what i did to get rid of the same issues. I am all stock includeing the 13.5 with a 9257 and a 3400g -- the tail wouldnt hold -- i went to a 9254 and man holds rock solid. I dont think theother two can cope with the torque put out by the Protos :0) The camera guy is new as well as the camera but at 1:20 theres 3 loops back to back and around 2:18 theres some pitch pumps -- holds without a worry ;0)

Markus


ROF sorry forgot to add the link ;0)

http://www.youtube.com/watch?v=bxtI_...e=channel_page

[nyc863]

I have S9257/spartan and it seems good at 13.5mm. It holds during full positive pitch climb, which must be about the most torque it has to do? Can't say what it does in tic-tocs or other more crazy moves. But I did spend quite a bit of time making sure the tail rod could be moved with my finger very easily, and there was no slop.

[dswitkin]

I had a very frustrating experience this morning. I had been increasing gain on my 401 to eliminate the yaw during fast climb problem. For this flight I set it to 90% AVCS on my 12FG. Took off with 13T/6S/90% throttle curve and flew for a couple minutes - no problems, no wag. I'm using the very flexible stock tail blades.

Then all of a sudden in gentle forward flight I got a bad shake, mostly in the yaw axis. I bled off some altitude then hit throttle hold, and managed to only bend the flybar. The tail looks fine, and so does the belt. I can't figure out what happened, and now I don't trust it. Any ideas?

Daniel

[dswitkin]

I think I had the gain way too high. I cut the tail guide off and used a new ball and link on the pushrod to get everything moving really smoothly. Now with the gain back at 50 AVCS is flies fine and didn't yaw in a strong climb.

Daniel