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Old Jul 22, 2012, 05:19 AM
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JDFiend's Avatar
Denver, CO
Joined Mar 2009
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Thanks Olli. I will do more testing and report back.

If the problem is gyro related, how would I correct that?
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Old Jul 22, 2012, 05:37 AM
OlliW
Joined Sep 2009
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Quote:
If the problem is gyro related, how would I correct that?
once we understand the issue we will know the solution... unfortunately we (at least I) do not yet understand the issue, so I can't tell what the solution would be
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Old Jul 23, 2012, 02:03 PM
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JDFiend, Your rudder stick to rotor turning as Olli mentioned is correct.

Here is my attempt to make clear what the problem that you are having is.

What you are saying is that with neutral rudder both top and bottom rotor blades spin ok with little or no left or right turning of the heli, as you increase the throttle, And that the problem occurs only when applying left or right rudder correct?

Could it be that your rudder stick movement is too sensitive and is producing more input (for motor speed up/slow down) than what is needed? Because the motor speed up/slow down is normal with the exception of the degree at which you say it is occurring.
What you seem to be saying is that the proportion of increase of one motor to the decrease of the other motor when applying rudder isn't what it should be, it is too uneven, unbalanced.
Try adding some rudder stick exponential and see if that helps to smooth it out.

Bern
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Old Jul 24, 2012, 12:21 AM
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Joined Mar 2009
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Bern,

I think you have described my problem fairly accurate.

I'll experiment with the exponential, and let you know what happens.

Thanks for that tip!

Joe
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Old Jul 24, 2012, 03:40 PM
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Denver, CO
Joined Mar 2009
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Well, I've experimented with several different dual rate and exponential settings on the rudder, but it doesn't seem to cure my problem.

Let me attempt to explain my exact problem a little better:

I apply light throttle at start up (10-15%) Both motors spin.
I give right rudder, A motor spins, B motor stops completely.

I return rudder stick to neutral (still at 10-15% throttle) A motor keeps spinning, B motor remains stopped.

I apply left rudder. A motor stops, B motor starts spinning.

I return rudder stick to neutral. A motor remains stopped, B motor keeps spinning.

Basically, both motors will never spin at the same time.

With rudder still at neutral, I increase throttle slowly. The one spinning motor speeds up.

Finally, when I reach somewhere between 50-70% throttle, the stopped motor begins to spin, and both motors now spin fast.

I am testing the heli on the bench without blades.

If I grab the tail and move the heli sharply at low throttle, there is no reaction.

If I grab the tail and move the heli sharply at high throttle (somewhere over 50%) it feels like the gyro action is kicking in.

I can't attempt a hover with the blades on, because any rudder stick input below 50-60% throttle will cause only one motor to spin, and the heli will go into a spin out of control in the corresponding rudder input direction.

I hope I have given you a clearer description of my problem.

Any advice?
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Old Jul 24, 2012, 05:22 PM
OlliW
Joined Sep 2009
1,770 Posts
Quote:
I apply light throttle at start up (10-15%) Both motors spin.
perfectly OK
Quote:
I give right rudder, A motor spins, B motor stops completely.
perfectly OK
Quote:
I return rudder stick to neutral (still at 10-15% throttle) A motor keeps spinning, B motor remains stopped.
perfectly OK
Quote:
I apply left rudder. A motor stops, B motor starts spinning.
perfectly OK
Quote:
I return rudder stick to neutral. A motor remains stopped, B motor keeps spinning.
perfectly OK
Quote:
Basically, both motors will never spin at the same time
have you ever attempted to move rudder just a very tiny bit to the left and right? I guess not, hence: perfectly OK.
Quote:
With rudder still at neutral, I increase throttle slowly. The one spinning motor speeds up.
perfectly OK (why not doing this without having moved the rudder widely around before )
Quote:
Finally, when I reach somewhere between 50-70% throttle, the stopped motor begins to spin, and both motors now spin fast.
perfectly OK
Quote:
I am testing the heli on the bench without blades.
good idea
Quote:
If I grab the tail and move the heli sharply at low throttle, there is no reaction.
what is low throttle? 10-15% as before? lower? higher?
Quote:
If I grab the tail and move the heli sharply at high throttle (somewhere over 50%) it feels like the gyro action is kicking in.
so many details on everything of little relevance, but finally reaching the point there things become interesting... nil... what should this "it feels like the gyro action is kicking in" tell us not very useful
Quote:
I can't attempt a hover with the blades on, because any rudder stick input below 50-60% throttle will cause only one motor to spin
with the heli at rest... this is a heading hold gyro, not a rate gyro!
Quote:
and the heli will go into a spin out of control in the corresponding rudder input direction
and as said a couple of times this is IMHO because of the gyro is acting in the wrong direction... and as also said a couple of times there is a simple test...
Quote:
I hope I have given you a clearer description of my problem
nice... a clear description of the results of the relevant test would be nice too
Quote:
Any advice?
my advices can be found in the above... it's up to you if you follow them or not...
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Old Jul 25, 2012, 02:12 AM
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JDFiend's Avatar
Denver, CO
Joined Mar 2009
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I'm sorry Olli. I was not trying to offend you.

I'm just having a difficult time trying to explain my problems clearly.

"When I return the rudder to neutral position, one motor continues to spin, and the other motor remains stopped."

This is not perfectly OK.

If both motors are not spinning with rudder at neutral, the heli will always spin in the opposite direction of the spinning blades because there is no counter torque.
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Old Jul 25, 2012, 02:29 AM
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Denver, CO
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Quote:
Originally Posted by OlliW View Post
Hey JDFiend,


I only can repeat myself and ask for this info
1) confirm and tell that your transmitter doesn't do any mixing
2) check out that you can identify all states and respective LED signals, and please confirm and tell that you got all signals...
3) please confirm explicitly that Motor A plug goes to motor A and analogously for B
4) if the heli is at rest and throttle is pulled down, the red led should be on. If you now move the throttle a little bit up, the red led should go off, and the blades should start. They don't have start exactly identically, but eventually both blades should spin at significant speed. Now, grab the tail and move it to the left and right and report back what the blades are doing.
Tests 1-3 I have done with proper results.

Test #4 result) (I retested again tonight.) I move the throttle up a little, say 5-10% estimated, both motors start slowly. I allow them to spin for a few seconds, and motor A stops spinning. Motor B continues to spin. I grab the tail and jerk it back and forth, right and left, and there is no change. Motor B continues to spin, and motor A remains stopped.

I believe that the motors should be alternating spinning speed as the tail is moved left to right, and vice versa in order to keep the heli straight in a "headlock." Am I correct in stating this?

Is it possible that my receiver could be bad? (Its an AR6100e)

Sorry Olli. I wasn't trying to insult your knowledge. I have a pretty good understanding of how coaxials work mechanically, and I can just tell that my setup "feels" completely screwed up somewhere, and I can't seem to narrow down the problem.

Could a bad receiver be the cause of my troubles?

Joe
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Old Jul 25, 2012, 12:01 PM
OlliW
Joined Sep 2009
1,770 Posts
Thx a lot for the new info. :-)

I am a bit confused about these two bits of information
Quote:
I apply light throttle at start up (10-15%) Both motors spin.
Quote:
I move the throttle up a little, say 5-10% estimated, both motors start slowly. I allow them to spin for a few seconds, and motor A stops spinning. Motor B continues to spin.
they seem to contradict

What is the difference between these two experiments/findings?

If its essentially always as stated in the second statement, this too me sounds as if the rudder signal drifts or - by whatever reason - is not centered. Could this be a strange setting in the DX7, or an unexpected mixing between signals, or something like that?

Maybe you could forward your DX7 settings to Luv for him to have a look at (I don't have a DX7, and the DX6i seems t be significantly different in some points).

The gyromixer calibrates rudder mid and gyro mid every time it transitions from the red led to no led (states Thro Low to Thro up). That is, if you pull down throttle and wait for ca 2 sec the red led will go on. The blades should not rotate in this condition. If you now push up throttle such that the red led goes off the gyromixer recalibrates and only then feeds a new signal to the motor outputs. So, whenever you get the red led you so to say reset the gyromixer and you should observe always the same behavior after you push up the throttle stick. What happens when you push up throttle (without touching rudder)? Both blades first start more or less similarily and then the system drifts such that one motor stops and the other runs fast? If you repeat do you get the same behavior?

Quote:
I believe that the motors should be alternating spinning speed as the tail is moved left to right, and vice versa in order to keep the heli straight in a "headlock." Am I correct in stating this?
yes, you're absolutely right, this is what should happen. Additionally you have to look at the rotation directions of the blades and which ones are getting faster and slower ... the induced torque must be such that the tail returns back, otherwise you also would get an uncontrolled spin very similar to what you describe (and this was actually what I was speculating about).

Quote:
"When I return the rudder to neutral position, one motor continues to spin, and the other motor remains stopped." This is not perfectly OK.
This behavior is IMHO perfectly OK because it's heading hold (and I actually tested it yesterday on my system before I answered). By pushing the rudder to one side you told the heli to yaw in this direction but it can't because it is at rest. If you now return rudder to zero you just tell the gyro that it should stop at the commanded new position but since it still hasn't reached this new position it still will try to catch up. Maybe its useful to think about it in terms of angles. If you push the rudder for let's say 1 sec to the left you commanded the heli to yaw by let's say 90. So, you pushed rudder and returned rudder to center, and the heli wants to go 90 degree. But it can't. So the stick is at center but the heli is still trying to move by 90...

So, in test (4) you actually don't have to "jerk" the tail, you just have to grab it and moving it gently to the left or right !!!

Consider that all these are effects are happening because the heli is at rest and not responding! So, your argument "If both motors are not spinning with rudder at neutral, the heli will always spin in the opposite direction of the spinning blades because there is no counter torque." doesn't hold since in flight the heli would respond and level at 90(in the above example).

Quote:
I move the throttle up a little, say 5-10% estimated,
I am not sure, but it could be that 5-10% is to less. There is a throttle threshold for the gyro/heading hold to set in. This is a security feature, since it prevents that if you handle the heli with throttle low that all of the sudden one of the blades start spinning. I can't recall from scratch what this threshold was. Maybe you have to spin the blades up a bit more and then do test (4).

I must admit that your case seems to be particularly tricky. Maybe I'll find time to post a video with the supposed behavior, not sure though.

One never can rule out the reciever (or any other piece of electronics), but I think you can test it by plugging servos at the respective ports.
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Old Jul 25, 2012, 02:55 PM
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JDFiend, I have just tried doing what you have been, with my BOL and I get the same results as you. While holding the heli down on the floor when I increase the throttle about 15 % and apply right or left rudder and let the rudder stick return to neutral the one rotor remains spinning and the other remains stopped.
However when I let the heli rise up into a hover then apply rudder and let the stick return to neutral I don't get that problem, and both rotors will spin to keep the heli in the air.

Perhaps you just have to try hovering it first without any rudder input and then when a few feet off the ground try applying a small amount of rudder to confirm this.
Bern
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Old Jul 28, 2012, 03:33 PM
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United States, WA, Spokane
Joined Oct 2010
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Agreed. All the OlliW gyromixers I use do the same thing while the heli is grounded. It is not until you spin them up high enough to get the heli airborne that both motors spin equally. It all has to do with gyro output. Even if and when you move the stick to get the other motor/blades spinning all you have done is given the gyro a command. It will slow down one set and spin up the others until the heli itself responds. Even to the point of the first set completely stalling. To get any of the helis to fly that I use with the OlliW gyromixer I have to give the throttle a quick stab to roughly 50 to 70% throttle to get the heli airborne. Or it will continue to set on the ground/table, whatever with one set fully spinning and the other seemingly lagging or not even moving. The second I get them up in the air I quickly reduce throttle to 1/2 or whatever is needed to keep it aloft in the enviornment.

Now what happens is the gyro itself is giving equal commands to each motor to countercommand any real axis movement. You can hold the heli in your hand with the blades free to spin and test this at low throttle settings just slightly below where the blades will spin up. Turn the nose left and the top blades spin to counteract the axis change, turn right and the lower blades spin to do the same thing. This is also how we test to see if the gyro itself is setup properly with the blade direction moving correctly also.

Top blades must spin counter-clockwise and the lower set spins clockwise. When the nose of the heli is moved in a left direction the upper blades spin (counter CW) and when the nose is turned to the right the lower blade set will engage and spin (clockwise). This is the easy no nonsense way to see if the gyro and motors are setup correctly.

Every heli I build, whether it be a vtail gyro setup or one of Olli's more advanced gyromixers, I do this test. But without blades. If anything varies from these results I always know the gyromixer L or R response needs to be reversed or my OlliW gyromixer output leads are connected to the wrong motor sides depending on how the heli responds. Easy!
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Old Jul 31, 2012, 12:19 PM
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Canada, ON, East Gwillimbury
Joined May 2012
7 Posts
Hey JD

You are having the exact same problems i had.

Reading this thread , it seems you are like I was , spending days trying to figure this out through questions and reading this forum and getting nowhere.

Also in youre case , it looks like the creator of this gyro Is taking offense that something could have gone wrong, and what we bought (i am assuming you bought yours like i did) doesnt damn well work.

The box I got with my gyro and usb cable in it said "2x gyro, 2x usb" so i am wondering if you bought yours from sven, and got the other gyro that originally came with mine from the source , and something along the way has happend to them.

Sven was great as he always is, and I got a refund for the cost plus the donation.
I was not happy that I am out $30 in shipping , here , then back, but I would be less happy if Sven was out that money as he didnt make the gyro and is only the middle man.

I put a dionysus mixer and a turnigy 302 gyro in , and my BOL is running great.

That ruled out any possibilities that something was wrong with the other components of my set up , and that I wasn't capable of setting things up right.
As when i started to report problems with mine here , I think it was immediately assumed that I had no idea what I was doing, if you go back and look through the posts.

This is a great invention by olli, but the possibility does exist I am sure that we may have found a couple that do not work, for whatever the reason may be
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Old Aug 01, 2012, 05:58 AM
OlliW
Joined Sep 2009
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Last edited by OlliW; Aug 01, 2012 at 01:39 PM.
Old Aug 01, 2012, 12:56 PM
Registered User
United States, PA, Clarks Summit
Joined Oct 2005
168 Posts
If I may I would like to make a statement to all involved with the GA250 Gyromixer problem.
As can be seen it is a frustration to each of you, JDFiend, The Saurus, OlliW and Erdnuckle2 alike, that this cannot easily be resolved.
What makes it so difficult is that where the fault lies, be it with the gyromixer or the user cannot be established for certain just by what has been posted in this forum. In all fairness the blame cannot be placed directly on the gyromixer or the user without further testing by someone familiar with the gyromixer and the involved helicopter.
I would hope that further comments about this matter which are directed to an individual and are not helpful or informational should be done in a Private Message.
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Old Aug 01, 2012, 01:40 PM
OlliW
Joined Sep 2009
1,770 Posts
thread closed
have fun
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