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Old Jan 23, 2010, 04:15 PM
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Well, I was just finished putting the heli back together and test flying after the tail rotor mishap last week. I hovered it and trimmed it for 5 mins and then re-charged the battery. I took it out and did 4-5 flips and rolls, stall turns, and sor forward flight and then the rudder trim started to go again and it was starting to piroutte on its own again. It would do one then stop, then another. I immediately flipped to normal mode and noticed the pirouttes getting more rapid. Luckily I got it down this time.

Any ideas fellas? Its like the gyro stops working all of the sudden.

Brian
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Old Jan 23, 2010, 05:06 PM
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Tumbler -

Is your Gyro sensitive enough where just a few more clicks of gain would cause tail wagging? Make sure the sensitivity is as high as it can go before wagging would kick in. Some cheaper gyro's will hold better in certain throttle ranges, so sometimes it's just a matter of finding that ideal throttle range and staying with it.
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Old Jan 23, 2010, 08:52 PM
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Yeah it is tured up around 70% and can;t go any higher or it starts to hunt. Remember I am flying this thing for 2-3 minutes and it is fine. I can slam full collective and it holds like a rock. I can flip in inverted and its no problem. However after a few minutes it looses its center gradually and then will eventually start piroutting it again.

Brian

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Originally Posted by rcnewb View Post
Tumbler -

Is your Gyro sensitive enough where just a few more clicks of gain would cause tail wagging? Make sure the sensitivity is as high as it can go before wagging would kick in. Some cheaper gyro's will hold better in certain throttle ranges, so sometimes it's just a matter of finding that ideal throttle range and staying with it.
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Old Jan 23, 2010, 08:57 PM
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I started a thread asking for help and some guys suggested there may be binding and the servo may be overheating. I will have to check but maybe the TY servo isn't up to the job even though it holds the tail ok.

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Originally Posted by rcnewb View Post
Tumbler -

Is your Gyro sensitive enough where just a few more clicks of gain would cause tail wagging? Make sure the sensitivity is as high as it can go before wagging would kick in. Some cheaper gyro's will hold better in certain throttle ranges, so sometimes it's just a matter of finding that ideal throttle range and staying with it.
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Old Jan 23, 2010, 09:03 PM
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Hmm, it could be the Gyro also, I guess the servo overheating makes sense, though I've never encountered that. Some Gyro's lose centering (just slightly) as the RPMs start to drop (battery pack is going flat), I've noticed this behavior with my 401b Gyro's, especially in colder weather. Even the more expensive Gyro's do this to some extent, but I've never had one go into an all-out piro, just gradual drift that can be easily trimmed out with a few rudder clicks. The drift is generally really minor, 2-3 clicks of rudder trim corrects it. If yours is going into an all-out piro, that is definitely reason for concern - you might want to double-check that issue in a warmer environment to see if the drift/piro can be reproduced there also, I'm assuming you're flying outdoors in the cold (like I am here out in WNY). If you think the problem is temperature-related, it could be the Gyro acting up on you, and you may want to consider swapping it out for a new one.
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Old Jan 23, 2010, 09:13 PM
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I just checked for binding and everything is smooth so thats not it. I wish I could try in a warmer environment haha. It doesn;t happen when just overing so its not a good test to bother doing it inside. Its only when it is flying around it happens. Tomorrow I am going to leave the heli outside for 15 minutes and then fly it and see what happens.

Yeah I know what you are saying about the rudder getting out of trim as the battery drops, that I have had happen too.

I think I may have to try another gyro like you said. Any suggestions for something on the cheaper side.....but something that still works well of course.

Brian

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Originally Posted by rcnewb View Post
Hmm, it could be the Gyro also, I guess the servo overheating makes sense, though I've never encountered that. Some Gyro's lose centering (just slightly) as the RPMs start to drop (battery pack is going flat), I've noticed this behavior with my 401b Gyro's, especially in colder weather. Even the more expensive Gyro's do this to some extent, but I've never had one go into an all-out piro, just gradual drift that can be easily trimmed out with a few rudder clicks. The drift is generally really minor, 2-3 clicks of rudder trim corrects it. If yours is going into an all-out piro, that is definitely reason for concern - you might want to double-check that issue in a warmer environment to see if the drift/piro can be reproduced there also, I'm assuming you're flying outdoors in the cold (like I am here out in WNY). If you think the problem is temperature-related, it could be the Gyro acting up on you, and you may want to consider swapping it out for a new one.
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Old Jan 23, 2010, 09:28 PM
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I started a thread asking for help and some guys suggested there may be binding and the servo may be overheating. I will have to check but maybe the TY servo isn't up to the job even though it holds the tail ok.
If the problem is overloading of the tail servo you might want to try using the Chinese weight mod to reduce the force required to move the tail grips. The guy mentioned in the Helifreak thread below makes units for both the standard and metal tails of the Trex500.

http://helifreak.com/showthread.php?t=105189
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Old Jan 23, 2010, 09:35 PM
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Interesting. I'll look into that thanks. How far out on the servo are do you guys have the ball on your TR servo. I am on the innermost hole which means the servo has to move the farthest to achieve the desired defection. That might a possible cause as well.

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If the problem is overloading of the tail servo you might want to try using the Chinese weight mod to reduce the force required to move the tail grips. The guy mentioned in the Helifreak thread below makes units for both the standard and metal tails of the Trex500.

http://helifreak.com/showthread.php?t=105189
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Old Jan 23, 2010, 09:52 PM
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I think I'm using the 2nd hole out on my TowerPro MG930 one-sided arm, I went by the measurements in the T-Rex 500 build manual to figure out where to place the ball link. You want as much movement of that servo arm as possible while avoiding binding, this will give you the highest resolution and the most precise tail control, so the further you can set your ball link toward the center of the servo arm, the better. If your ball link is too far out, you will run into binding issues unless you dial down the limit for servo arm travel on the Gyro, technically you want this value as close to 100% (full) as possible. The Chinese weight mod will reduce load on the tail servo but the video on helifreak has been questioned many times for its accuracy and integrity, it was a bit over-done and exaggerated.

Tumbler - the reason I wanted to verify that you were flying in the cold is that I think the overheating servo theory is not the problem, though perhaps remotely possible that it's causing issues. I'd suspect the Gyro first, and I am betting the cold temps have something to do with it...
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Old Jan 23, 2010, 10:39 PM
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I just moved out toi the second hole and will try that. I may have had the travel on the gyro set too high and maybe had some binding issues. I'll try it out again tomorrow with the finger on the throttle hold ready for an auto at any second.

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Originally Posted by rcnewb View Post
I think I'm using the 2nd hole out on my TowerPro MG930 one-sided arm, I went by the measurements in the T-Rex 500 build manual to figure out where to place the ball link. You want as much movement of that servo arm as possible while avoiding binding, this will give you the highest resolution and the most precise tail control, so the further you can set your ball link toward the center of the servo arm, the better. If your ball link is too far out, you will run into binding issues unless you dial down the limit for servo arm travel on the Gyro, technically you want this value as close to 100% (full) as possible. The Chinese weight mod will reduce load on the tail servo but the video on helifreak has been questioned many times for its accuracy and integrity, it was a bit over-done and exaggerated.

Tumbler - the reason I wanted to verify that you were flying in the cold is that I think the overheating servo theory is not the problem, though perhaps remotely possible that it's causing issues. I'd suspect the Gyro first, and I am betting the cold temps have something to do with it...
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Old Jan 23, 2010, 10:53 PM
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Another question for you guys. Can somone spin their blades by hand with your hand on the boom. Do you feel anything. It doesn't feel so much like a vibration, but you I feel something through the boom when I spin the blades. Just wondering if that is normal.

Thanks,

Brian
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Old Jan 24, 2010, 01:16 AM
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I myself am also experiencing notchy blade grips at this time,
i considered buying the Align thrust bearings and washer spares but decided to take somebodys advice and first buy the Align black dampeners and try and see if they can make the grips smoother, wanting to replace as little as possible before flying.

I have also bought the metal mixing arms and washout arms in the one kit as the ball link will hold much better in the metal than the plastic arm.
Later i will let you know if i the dampeners work better,

Cheers Michael
please share your experience with us.
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Old Jan 24, 2010, 01:20 AM
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[QUOTE=kctrading;14148800]
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Originally Posted by markos51 View Post

What are the pros and cons of upgrading to a CF main frame? I am running a AR7000 with dual RX's

Thanks,
if you ask me ,i do not know.I still wait for my metal kit.
When i am ready i will write my comments
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Old Jan 24, 2010, 01:41 AM
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markos -

Within the DX7 (not sure about other radios), end point adjustment will actually change the rate of travel of your rudder servo. The Gryo controls the throw distance, but the EPA adjustment in the radio controls the speed. Check the EPA of the "gear" channel (if that's what you're using), it often defaults to 50, so bump it up to 70-80 and you should see a difference. If your end points are already at max, your tail servo is probably just slow or does not have enough torque.

I should add that head speed also affects piro rate, the slower your head speed, the slower your piro rate. If your blade RPMs are on the low end (< 2200 RPMs), your piro rate won't be all that impressive.
Thank you very much for your help.
I have dx6i .
Rudder travel (is this ETA ?)ajustment is at his limit.
Throtle curve is in third position (Hovering) 70 % engine power.
In gear chanell i conect the sesivity of the gyro (it is 62%)
The only thing i can do is to move last hole close to servo center.
So the servo will have more torqe.
Otherwise i will change the servo.
Thank you once more
Markos
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Old Jan 24, 2010, 02:02 AM
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Quote:
Originally Posted by rcnewb View Post
markos -

Within the DX7 (not sure about other radios), end point adjustment will actually change the rate of travel of your rudder servo. The Gryo controls the throw distance, but the EPA adjustment in the radio controls the speed. Check the EPA of the "gear" channel (if that's what you're using), it often defaults to 50, so bump it up to 70-80 and you should see a difference. If your end points are already at max, your tail servo is probably just slow or does not have enough torque.

I should add that head speed also affects piro rate, the slower your head speed, the slower your piro rate. If your blade RPMs are on the low end (< 2200 RPMs), your piro rate won't be all that impressive.
Thank you very much for your help.
I have dx6i .
Rudder travel (is this ETA ?)ajustment is at his limit.
Throtle curve is in third position (Hovering) 70 % engine power.
In gear chanell i conect the sesivity of the gyro (it is 62%)
The only thing i can do is to move last hole close to servo center.
So the servo will have more torqe.
Otherwise i will change the servo.


Edit >Finally i moved in the last whole close to the servo center and in my case worked.
Now i can increase servo travel, the servo is stronger now and i cane increase gyro sensivity from 60% to 66.Tail wagging (in hover) disapered.
Thank you once more
Markos
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