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HelicopterMain Discussion › How warm is your tail servo after a flight?
07-09-2008 10:11 PM  9 years agoPost 1
QuantumPSI

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Atlanta, GA

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I just got back from flying my Raven and I touched the tail servo and noticed that it was warm and if you left your finger there long enough, it'd feel pretty hot. I was just wondering if this is normal? I'm running a GY611 w/9256. Originally, the gain was at 41% but I dropped it down to 36% to protect the servo. It doesn't hold as well and so I'm going to move the ball out a little to make up for the drop in gain.

Another concern, my tail NEVER stays straight during flips. This actually happens on all of my machines. I know it's a setup issue, but I really don't know how to fix it. And to answer the obvious, yes I set it up in normal mode first but beyond that, the nose still turns when doing inverted loops and such. I find myself correcting all the time. Any and all advice is appreciated.

...now where was I, dh/dt = BS-dx/dt
I will fly you forever... till earth do us part

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07-09-2008 10:21 PM  9 years agoPost 2
nmrs

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Austin, TX

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Another concern, my tail NEVER stays straight during flips. This actually happens on all of my machines. I know it's a setup issue, but I really don't know how to fix it.
Does it happen on the sim as well? Since it happens on all of your helis, are you sure you're not accidentally giving a little rotor input when moving the collective during the flip? Should be easy to test out -- put a silly amount of expo (60, 70, 80, etc) on the rudder and see if the tail stays straighter when flipping... You could do the expo test on the sim if you were worried about flying your real heli with your controls that out of whack.

450 se v2

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07-09-2008 10:22 PM  9 years agoPost 3
QuantumPSI

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Atlanta, GA

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Perfectly straight on the sim. I actually spent some time a while back working on really basic things to ensure I don't give unwanted inputs. My loops and flips are as straight as an arrow on the sim except for when I try to move them around.

...now where was I, dh/dt = BS-dx/dt
I will fly you forever... till earth do us part

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07-10-2008 12:38 AM  9 years agoPost 4
Yug

rrMaster

UK. Herts

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It's normal for things to be warm after a flight, afterall, they've been working quite hard. There's a difference however between warm and HOT. Hot means something is not setup right and being over stressed.
I'm supprised you're having issues with the tail on simple flips, especially if it's a 611/9256. However, no gyro is impervious to vibes. Perhaps your gyro mounting technique needs redressing. I had similar problems with SL720s which were resolved by tuning the mounting. Too soft and you get a cyclically induced wobble on the gyro which leads to precession errors or drift which causes the tail to step out in a flip due to the 'hammer blows' through the airframe from the head. It's a bit like a destructive resonance is setup in the gyro. As the mounting becomes stiffer, the tail runs truer. However if the mounting gets really stiff, then you get the similar cyclic wobble in resonance with the engine vibes so you see the tail drifting in a simple hover.
An obvious thing to check is revo mixing or any other kind of mixing you may have inadvertently enabled.

Vegetable rights and Peace

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07-10-2008 01:04 AM  9 years agoPost 5
Yug

rrMaster

UK. Herts

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The other thing I forgot to mention was the tailblade setup. I did a load of work last year on chinese weights. Some grips/blade setups offer huge load forces to the tail servo, which, inevitably resulting in the tail servo being overworked with a result in a degredation in performance as well as excessive wear on tail pushrods etc. If you can be bothered, it's well worth tuning your tail grips & blades with chinese weights.

Vegetable rights and Peace

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07-10-2008 01:42 AM  9 years agoPost 6
tchavei

rrProfessor

Portugal

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Well if you had asked me last week, I would have told you that my tail servo (bls251) got warm enough to start being really unconfortable to hold your finger for more than 5-6 seconds. Since then I dropped the voltage to 4.8V (had 5.2V previously) and somehow the servo is mildy warm (if warm at all).

About the tail moving during flips. Its collective management. If you bang the sticks to do the flip, the "hammering" as Yug described it will happen and make the tail move. I had the 611 and it was clearly visible. With my spartan its almost non existent unless there is really heavy side wind and I'm stick banging through the flip.

When I stick bang during tic tocs (close to me) with my vibe 50, I can see the entire head and structure momentarily shake at the precise moment when I do a pitch reversal (ie 13 to -13). When I'm thinking about what I'm doing, I can do fast tic tocs and yet be smooth during pitch reversal so the hammering doesn't occur.

The best way for me to perfect a maneuver is to repeat it hundred of times changing pitch and cyclic until I reach the sweet spot ie where minimum input is required to do the maneuver. Think like you're leading the bird in a dance... it helps

Tony


--------------------
"Perfection and patience usually walk side by side..."

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07-10-2008 06:42 AM  9 years agoPost 7
QuantumPSI

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Atlanta, GA

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Thanks for all the great advice everyone. I'm curious to know, what kind of mounting tape are you using with your GY611s?

...now where was I, dh/dt = BS-dx/dt
I will fly you forever... till earth do us part

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07-10-2008 07:32 AM  9 years agoPost 8
buburub

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Bayside, NY

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Hey QuantumPSI,
Your issue is probably with the gyro setup and not with collective management because you are not experiencing it on the sim. The best mounting tape for the gyro is the Kyosho zeal green tape. This can solve a whole bunch of gyro related issues in one shot including (tails drifting, tail shakes).

611 Setup (According to a few pros)

1) Make sure it's on 3D Mode, not F3C
2) Keep AVS at 100 (gain)
3) Put some delay on starting and stopping (10% start, 50% stop)
4) When setting up the tail go to non heading hold mode (normal mode)
5) Make sure the end points (on gyro and radio)for right and left is at 100
6) Keep Exponential and Dual Rates linear on the radio for now.
6) Adjust the linkage going from the servo to the tail so that the travel going to the right or left for the pitch slider is the same and when you let go of the stick, the pitch slider goes into the center of the tail shaft. You do NOT want binding on either end.
7) Your end points (on gyro not radio)should be close to 100/100 if it's off then your using the wrong hole on the servo horn.
8) Change the end point (on the gyro not radio) so that your get full range without binding. Ideally it would look like 100/100, but you might end up with 95/95 or 105/105 or something similar. The end point must NEVER be different 105/95, 110/90 this is a big no no.
9) Now you can put your gyro back into heading hold mode.
10) Use the end points (on your radio) to set the desired piro rate

If your servo is getting hot then it's probably because it's on the wrong hole, gyro is not setup correctly or the gain is too high. Typical gain on a stratus is 35-37% and on a Trex 600 is 28-32%. 40% gain or higher seems too high for a 611.

Best Regards,
Bub

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07-10-2008 07:58 AM  9 years agoPost 9
w.pasman

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Netherlands

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I'm using a CSM560 with 9254 and I never noticed it getting hot or warm. I will check again as I recently modified the gyro settings to give a tighter control
Another concern, my tail NEVER stays straight during flips.
Is your gyro mounted perfectly straight?

Most sims are not 100% accurate in simulating a real world. I'm using reflex and I noticed several deviations from 'reality'. One is that the tail responds instantly and the piro speed is there also instantly. Real machines need some time to reach the target piro speed.

Also if you have side wind (in practice you always have some) a real heli will tend to roll a bit. During longer maneuvers like large loops, the heli therefore never will keep perfect in track. With flips this should not be an issue though.

Finally, if the heli does not keep the tail straight during a flip, your elevator input will effectively be translated into partial aileron input.

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07-10-2008 12:16 PM  9 years agoPost 10
tchavei

rrProfessor

Portugal

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Well maybe its just me but when I do a dirty flip (read as bang pitch up, bang cyclic backwards, bang pitch down) then damm me if the heli stays strait (doesn't matter if vibe, evo or 600N).

Tony


--------------------
"Perfection and patience usually walk side by side..."

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07-10-2008 01:04 PM  9 years agoPost 11
buburub

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Bayside, NY

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Side wind or bad collective management can cause tail torque. But other than that you should be able to flip without any tail yaw. This is why we spend so much money for the new gyros. Haven't you seen people do statinary flips?. How is this accomplished without a rock solid tail? Me and my friends have been able do these flips with no tail yaw for as long as I can remember. One test you can do to test if you've setup your tail correctly: Get your bird into an upright hover and punch it up (positive collective) then punch it down (negative collective). If the tail torqued going up or down, then the tail was setup incorrectly. Check your setup.
Best Regards,
Bub

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07-10-2008 02:19 PM  9 years agoPost 12
tchavei

rrProfessor

Portugal

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Side wind or bad collective management can cause tail torque.
Thats what I was trying to say. In these conditions it can happen. Not on a low wind day with a realistic pitch control (ie not slapping from -14 to 14).

Tony


--------------------
"Perfection and patience usually walk side by side..."

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07-10-2008 04:46 PM  9 years agoPost 13
QuantumPSI

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Atlanta, GA

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WoW thanks for the advice guys. That really helps out. I've been using CSM gyro mounting tape. Since I started doing mild aerobatics, I've gone through about 3 or 4 different mounting setups and none has worked perfectly, but the CSM stuff has worked the best for me so far. In any case, where can I find this zeal stuff?

...now where was I, dh/dt = BS-dx/dt
I will fly you forever... till earth do us part

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07-10-2008 04:49 PM  9 years agoPost 14
tchavei

rrProfessor

Portugal

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Bergen RC carries the stuff. I would put a strap over the gyro though as it feels too soft and you loose precision if you use it without a strap.

Tony


--------------------
"Perfection and patience usually walk side by side..."

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07-10-2008 05:42 PM  9 years agoPost 15
MattJen

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UK

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I'm using a CSM560 with 9254

The servo's are compeltely different,

First question i would ask is what is your gain set to ?

As prev poster said anything above 40% is too much and the servo will get too warm and there has been cases when these first came out that the servo's were failing cos they had been set with too high gain, what happend was some pilots swapped over from the 9254 and started to use the better 611 gyro, they set the gaint oo high 75% ( which is what the 401 was around) and of course burnt the servo out..
cos the movement of this servo was undetectable due to being much faster..

Matt

All The Best

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07-11-2008 08:00 PM  9 years agoPost 16
w.pasman

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Netherlands

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First question i would ask is what is your gain set to ?
I have 92% gain in idle-up. Again this is a CSM560 not a 611.

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07-11-2008 08:47 PM  9 years agoPost 17
Riq

rrKey Veteran

ND

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Ok, maybe simple q's, but I gotta know.

611 gain at 100%? Ive heard to keep mine at 37-39%

AND

Ive been led to believe just eying 3-4 degrees is enough on a 601/611....(ASJ)

This sounds like issues ive encountered, but always think its vibrations, or this or that.....

Im open, so enlighten me, PLEASE!!!

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07-11-2008 08:51 PM  9 years agoPost 18
QuantumPSI

rrElite Veteran

Atlanta, GA

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Ok, so I just got back from flying. I moved the tail control ball out a hole and dropped the gain. The tail actually flies much better now, but still not perfect. I did everything that was mentioned by buburub except the delay. I don't know exactly where my manual is and didn't want to look for it (just being lazy and wanted to fly ). What exactly does delay do?

Also, I need to mention that it was pretty windy today, I wanna say about 10mph consistently. Perhaps this is more of the cause of my problem than anything else. I really can't tell.

Question, after a flight, does the 9256 drift when it's sitting on the ground? When I power up, it's dead still but after a flight, it continues to drift when the engine is off and it's sitting still. The funny part is, if I flip into normal mode, the servo doesn't drift anymore. This behavior actually appears on my 600N as well and Stratus. Neither the 600N or Stratus has been crashed and the gains are not too high (37% on stratus and I think 30% on 600N). The GY611 on the Raven has been crashed but it was sent back to Hobby Services and they said it was fine. So I'm just wondering if it's normal or not. I've always thought it was because it's on all 3 of my nitro machines.

...now where was I, dh/dt = BS-dx/dt
I will fly you forever... till earth do us part

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07-11-2008 10:25 PM  9 years agoPost 19
buburub

rrApprentice

Bayside, NY

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In regards to delay: (according to bobby)

DIIA - 15% (initial start of piroette delay)
DIDA - 50% (stopping of the tail in the middle of a piroette delay)

Delay is used to save the tail gears from stripping out from hard start and stop tail inputs.

The drifting is normal in heading hold mode and when you switch it to normal it should center again with no drifting.

Make sure your limits on the gyro going to the left and right are the same (100/100, 98/98, 102/102, etc.). When you give full right and left tail inputs make sure there are no binding and that the travel is full. A second way to dialing in the tail is to go to the field and run the gyro in normal mode (not heading hold mode). Adjust the linkage until the tail does not drift. This would get it very close to the other method.

Bub

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07-12-2008 01:44 AM  9 years agoPost 20
Wyn

rrApprentice

Oregon, USA

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Question, after a flight, does the 9256 drift when it's sitting on the ground? When I power up, it's dead still but after a flight, it continues to drift when the engine is off and it's sitting still.
Drift in AVCS while sitting still on the ground with the engine off is not normal, unless it's really-really slow. It shouldn't drift before the flight (after initialization), and if it drifts afterwards the problem is likely with the gyro sensor, the pot for the rudder stick on the TX, or something else in the RX or TX that would shift the rudder signal slightly. It could be temperature related. The speed that it drifts represents the magnitude of the problem.

If you have a meter to measure the pulse width from the RX, it's pretty easy to determine whether the problem is on the radio side or the gyro side. Just measure the pulse initially, then measure later when it's drifting. The pulse width should be the same; if so, it's the gyro causing the drift. If not, it's radio related.

Wyn
VoltMagic

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HelicopterMain Discussion › How warm is your tail servo after a flight?
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