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Raptor E325 › Pirouetting when hitting throttle hard.
07-09-2008 06:56 PM  9 years agoPost 1
Friday_2008

rrApprentice

Athens, Greece

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Hi guys

My Titan is pirouetting when i hit the throttle. I am at a hover and when going on full throttle (Not smooth) tail starts doing pirouettes.

This is happening both on HH and Rate. Everything seems to be ok, i don't have any wobble when i fly smooth and tail holds perfect when i fly normal.

Also when i switch from HH to rate it seems that tail turns right making the nose turning left.

I am trying to counteract it by moving the servo. It correct it a bit, but didn't eliminate it.

Any thoughts would be welcome

Thanks

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07-10-2008 12:12 AM  9 years agoPost 2
fenderstrat

rrProfessor

Aston,Pa

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what gyro and servo?
what are your gain settings?did you set it up in rate mode first?

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07-10-2008 12:21 AM  9 years agoPost 3
redvtr1000

rrVeteran

covington, GA

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you didn't mention if this is in normal or idle up.

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07-10-2008 06:51 AM  9 years agoPost 4
GPyan

rrNovice

Brunei Darussalam

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Hi Friday_2008

Could i know what is you max pitch??

i did encounter this problem with my trex 450 and the reason was my pitch was too high (14 degrees) which cause the headspeed to drop and as a result the tail swing. reducing the pitch down to 10 degrees seems cure the problem.

good luck n hope its works with you as well..

GPYan

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07-10-2008 07:35 AM  9 years agoPost 5
Friday_2008

rrApprentice

Athens, Greece

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Ohhhh guys one by one !

Gyro is Futaba GY401 and tail servo s9257. Gain settings are HH : 80% and Rate : 25% and yes i set it up on rate. I have only normal mode. I don't use any idle up at the moment.

I have to say here that heli flown and still flies good while tail holds good. This pirouetting problem comes only when i go hard on throttle. If i go smooth there is no problem.

Also when i hover at HH when i switch to rate nose start to turn left.

@Gpyan

My pitch range is -2 +5 +10 but it might has to do with headspead. You are leading me to believe that motor bogs down when i go hard and headspeed drops resulting the tail to pirouette. I might also check my pitch range again.

Thanks

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07-10-2008 10:38 AM  9 years agoPost 6
Yeldcat87

rrNovice

Pretoria - South Africa

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Hi there

I have the same problem with my MT, I've tried reducing the gain because I thought it was maybe overcompensating but it doesn't seem to change and mine also only does it when I rapidly open the throttle. I'm using a GY401 with 65% gain and a GWS HPF-X tail servo.My pitch ranges from -10 to +10

As for your tail drifting in rate mode that you must set with the linkage rod to the tail pitch, just see which way the tail servo moves when you give it right rudder( which will compensate for your drift to the left) and then either shorten or lengthen the rod accordingly, I think you have to do this mechanically as close as possible because one can't use the trim or sub-trim on the radio to stop it because then when you switch back to AVCS(HH mode) the gyro will take the sub-trim/trim as the center and then the heli may even drift in HH mode so try get it 100% setting it mechanically then there should be no drift in either mode.

BTW what throttle response on the ESC are you using? Quick,Standard or Soft? I have a feeling changing that might help...maybe the gyro can't keep up with the quick acceleration and therefore make it pirouette...just a possiblity I haven't checked mine I think it may be in Quick response mode but I'll let you know if I sort mine out,, it just hasn't really bothered me too much

Good Luck anyway!

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07-10-2008 10:50 AM  9 years agoPost 7
Yeldcat87

rrNovice

Pretoria - South Africa

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Oh I forgot and I doubt it could be the headspeed because I fly in Idle-Up 1 and the throttle curve is a V from 90% 75% 90% throttle and the throttle was calibrated when I set the ESC up and it still does it but only when I rapidly open the throttle else it doesn't happen...

But go look at [url=http://www.raptortechnique.com] if you haven't yet there's a lot on Gyro set-ups as well as problems, maybe that will help although its based on the nitro raptors it still may help.

Cheers...

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07-10-2008 12:07 PM  9 years agoPost 8
Friday_2008

rrApprentice

Athens, Greece

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BTW what throttle response on the ESC are you using? Quick,Standard or Soft?
I am using the stock esc setup. I haven't changed anything on the esc. If you have any news after playing with the esc let me know pls. As i won't fly until Monday.

Thanks

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07-10-2008 01:10 PM  9 years agoPost 9
fenderstrat

rrProfessor

Aston,Pa

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Also when i hover at HH when i switch to rate nose start to turn left.
then it is not yet quite 100% set up.try to get it so there is NO drift when in rate mode.you will need to slide the servo forward slightly.then fine tune using the linkage(if its slight drift then use linkage only).no trim or sub trim on ch4.after this adjust your gain .a 401/9257 should hold that tail solid as a rock,also where is the ball on the servo horn located?

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07-10-2008 03:24 PM  9 years agoPost 10
stocky

rrKey Veteran

Taxachusetts

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My Titan is pirouetting when i hit the throttle. I am at a hover and when going on full throttle (Not smooth) tail starts doing pirouettes.
Complete piroettes ? or does the tail just go to about 90 degrees and then comes back?

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07-10-2008 05:57 PM  9 years agoPost 11
Friday_2008

rrApprentice

Athens, Greece

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Complete piroettes ? or does the tail just go to about 90 degrees and then comes back?
Complete. It stop doing that, when i come back on throttle. When i back off on throttle it stays in the last position of pirouette.
where is the ball on the servo horn located?
Servo has 4 holes, i have the ball in #2 from the inside. I tried in every hole. In the 2 outer, i got a bad tail wag even with 52% of gain. In #1 it holds it, but not so good and #2 seems to be the correct one. It stills drift, but much less.

I know that when i get drift in rate, it has to do with a bad mechanical tail setup. And this is something i can fix, but what concerns me most is doing pirouettes in full throttle.

I almost crashed when i tried to make my first loop. Thank god i was at a high altitude. When heli got vertical tail went crazy and was pirouetting. I got back to hover and did a hard kick on throttle and found this problem.

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07-10-2008 08:47 PM  9 years agoPost 12
RMG2

rrApprentice

Oregon, USA

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What fenderstrat said! You need to setup the tail servo/linkage to zero yaw in rate mode mechanically before you can expect the gyro to hold properly.

Other issue might be binding in the tail mechanics, or belt tension issues, or a slipping one-way bearing??? Something that is not allowing the tail blades rpm to keep sync. with the main blades speed???

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07-10-2008 09:04 PM  9 years agoPost 13
gmcullan

rrKey Veteran

Southbridge, MA

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Depending upon your LiPo pack, connectors, ESC BEC circuit, mechanical friction even, you might be having a monentary voltage drop when you nail full throttle that the BEC isn't compensating for. That could destabilize the gyro and allow the piro. Then when you back off the throttle to a lower setting, the system voltage stabilizes and the gyro comes back on line.

Just a thought!

Gerry Cullan,
Gaui 200, 255; T-Rex 250, 450 SE & SA, Mini-Titan, Blade 450

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07-11-2008 09:01 AM  9 years agoPost 14
Friday_2008

rrApprentice

Athens, Greece

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You need to setup the tail servo/linkage to zero yaw in rate mode mechanically before you can expect the gyro to hold properly
This is something that it must be done and checked at field. Actually i ve made some mechanical changes when the problem occured and it seemed to got better, but didn't vanish.
you might be having a monentary voltage drop when you nail full throttle that the BEC isn't compensating for. That could destabilize the gyro and allow the piro
I just ordered an Eagle Tree system and when i ll put it on, things will show and i would be able to clear things out.

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07-11-2008 02:07 PM  9 years agoPost 15
fenderstrat

rrProfessor

Aston,Pa

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This is something that it must be done and checked at field
WHY?you can test hover in your yard or small area to check for drift.you only need to get the heli into a stable hover
Servo has 4 holes, i have the ball in #2 from the inside. I tried in every hole. In the 2 outer, i got a bad tail wag even with 52% of gain. In #1 it holds it, but not so good and #2 seems to be the correct one. It stills drift, but much less.
sounds like you need to use one of the first 2 holes and up the gain.I think many people with your set up are in the 70-80% range.everyone's set up numbers will be different but that should get you in the ballpark

also, is this new equipment?is there any chance the servo is on its way out?

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Mini Titan/SE
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07-11-2008 02:28 PM  9 years agoPost 16
Friday_2008

rrApprentice

Athens, Greece

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WHY?you can test hover in your yard or small area to check for drift.you only need to get the heli into a stable hover
I have to go to the park. I can't hover inside my apartment

As for your second statement i am at 70-80% range too. In this gain range heli seems to feel good.

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07-31-2008 03:42 PM  9 years agoPost 17
Richardmid1

rrProfessor

Leeds, England

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The problem is that you are hitting the throttle in normal flight mode and the motor is speeding up fast creating too much torque for the tail to handle. You need to increase the second and third points in your throttle curve and back off the high point to about 80% so that your throttle curve increases sharply up to mid stick then tails off. You should have about -4 degrees pitch at low stick, 0 degrees at mid stick and about +9 degrees at high stick.

60% of the time, it works every time!

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Raptor E325 › Pirouetting when hitting throttle hard.
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