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11-28-2007 10:22 PM  9 years agoPost 41
Sam2b

rrElite Veteran

Seattle, WA

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Here's the answer. While in non-head holding mode, you can sub-trim the tail to a stationary hover at the desired RPM. Then, when switched to head holding mode for the next flight, the gyro uses that servo position as center.

The reasoning: when you are not giving rudder stick input, the tail stays put without the gyro working to keep the tail stationary. This is desirable for optimized performance of the gyro. (my opinion)

I too did not understand this concept for many months, and was against the theory. But later learned the value. It is best to talk in person about this subject. Reading text can wear you out!

AceBird is correct.

_Sam B_
Team MSH USA * Protos Max * Xpert servos * Cyclone Blades * ProgressiveRC * VoltMagic * Ecalc

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11-28-2007 10:29 PM  9 years agoPost 42
jschenck

rrProfessor

La Vista, NE.

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While in non-head holding mode, you can sub-trim the tail to a stationary hover at the desired RPM. Then, when switched to head holding mode, the gyro uses that servo position as center.
try that - I think you'll find that the tail will drift in HH mode unless you reset the gyro to relearn center from the trim adjustments.

You can use the trim (not sub-trim) to get the heli to stop drifting in non-HH mode, land, then adjust the mechanical linkages to the same slider position without any trim. Now you will have a tail that should not drift in non-HH and HH mode - performs great.

This is my method for a 401 setup.

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11-28-2007 11:19 PM  9 years agoPost 43
Avi

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Israel

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You don't have to adjust the links. you can simply reset the gyro either by turning it off and on again, or by alternating switch positions rapidly a few times.

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11-29-2007 12:30 AM  9 years agoPost 44
AceBird

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Utica, NY USA

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I think you'll find that the tail will drift in HH mode unless you reset the gyro
Yes, of course, you have to initialize the gyro to the new center. As far as the servo is concerned sub-trim and trim are the same. The only difference is sub-trim affects all four flight modes and trim only affects the mode you are in at that time. So you can have different trim values for different flight modes. If these flight modes are HH modes then you must initilize to that mode you intend to use or they have to be the same if you flip between them.

As I said before if your idle up headspeed is different than your normal headspeed you can adjust the TRIM in the non HH mode (NORMAL) so the tail doesn't drift. And the 401 will be happy.
Why would you want to use sub-trim on a 401?
I am a perfectionist, whether I need it or not that is what I will do. You can only get so close mechanically. Electrically (program wise)you can get bang on. Second you cannot mechanically adjust for two different headspeeds IMPOSSIBLE.

Ace
What could be more fun?

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11-29-2007 01:23 AM  9 years agoPost 45
lperagallo

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Westfield, Indiana, USA

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Ace,
Second you cannot mechanically adjust for two different headspeeds IMPOSSIBLE
What does headspeed have to do with a HH Gyro? It holds the tail electronically. It does it's job regardless of tail blade speed. It may give more command at a slower tail speed, but I've never heard anyone ever use headspeed as a parameter for setting a Gyro. Where have you ever seen anything in a Mfg manual that talks about headspeed and Gyro together
You can only get so close mechanically.
Oh and by the way.....When you buy a quality heli you will be able to adjust the tail mechanically to get it spot on. My Bergen has adjustments within the tail for set up. I set the mechanical linkage with the pitch slider dead center. I then adjust the tail links to get the proper hover position and tail blade tracking.

Sam2B Says
Here's the answer. While in non-head holding mode, you can sub-trim the tail to a stationary hover at the desired RPM. Then, when switched to head holding mode, the gyro uses that servo position as center.

The reasoning: when you are not giving rudder stick input, the tail stays put without the gyro working to keep the tail stationary. This is desirable for optimized performance of the gyro.
Sam2b must be the brother of Ace. Again if this is proper procedure why isn't it documented on the Futaba site. I'm amazed at all the secret information being passed around. i feel privileged to be reading it.

And for the record.....the original post is about a 601 not a 401.

Lou

Twin Bergen 44Magnums FBL Wren NW44s - Kero start

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11-29-2007 02:42 AM  9 years agoPost 46
Chopper Man100

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Canton GA.

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I have not read through all these postings and don't want to. Just sticking my two cents in, don't forget to make sure revolutionary mix is inhibited in the radio for the tail rotor controls.

Well maybe three cents.. every gyro I have set up, the instructions say to mechanically adjust the tail rotor linkage so the tail holds steady when in nomral mode (non head holding) before using head holding mode. However, I have skipped that step temporarly on some heli's and the tail rotor seems to hold fine, but I always go back later and set it up.

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11-29-2007 02:51 AM  9 years agoPost 47
sla

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wasilla,ak,99654

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ok so i adjusted tail slider a little out of 90. now it went the other way a tad bit. so i will go back a little bit. as far as buying a quality heli that has a adgustment to trim the tail mechanically perfect, i thought miniature air was one of the best for quality. and the 601 is mounted proper.

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11-29-2007 06:44 AM  9 years agoPost 48
Avi

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Israel

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sla, I am saying it agin: It would be hard to go VERY wrong mechanically if you go by your manual. What is more important, is that the behavior that you describe does not match HH!
You might have just been mistaken, and thought it was supposed to be HH. Then it's ok. Otherwise, if it really was supposed to be HH, then your gyro is not working correctly!
Make sure your gyro works properly before trying anything!

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11-29-2007 01:47 PM  9 years agoPost 49
FCM

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Surrey, England

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I agree with Avi. These modern gyros will normally fly fine with minimal set up required. If you have all of your transmitter trims set to zero and have followed the Min Air tail linkage instructions, the heli should at the very least, hover with a locked tail in heading hold mode. If it will not then something else is wrong. The mechanical tail trim is not critical to achieve this.

Paul.

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11-29-2007 05:38 PM  9 years agoPost 50
AceBird

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Utica, NY USA

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Where have you ever seen anything in a Mfg manual that talks about headspeed and Gyro together
I haven’t.

Its logic or common sense to some people. If you don’t pay attention to headspeed then the control is biased to one side always making up for a torque that shouldn’t be there. Probably the only place that you will witness the ill effects is on spool up when some helis will kick in one direction or the other just before lift off and then come back to where the gyro was initialized. If you are happy with that behavior then I guess it doesn’t matter.
My Bergen has adjustments within the tail for set up. I set the mechanical linkage with the pitch slider dead center.
What adjustments does your Bergen have for compensating mechanically for the non linearity of the pitch blade link? If there is no adjustment than having the pitch slider dead center means nothing.
And for the record.....the original post is about a 601 not a 401.
>
>
Why would mechanical a out of trim condition affect heading hold mode? Does the 601 gyro work differently to say a 401?
Paul brought it up. And the question has been answered. Because you don’t like the answer you start insulting people on this forum. Now there is one more person who has your number.

Ace
What could be more fun?

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11-29-2007 06:14 PM  9 years agoPost 51
lperagallo

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Westfield, Indiana, USA

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What adjustments does your Bergen have for compensating mechanically for the non linearity of the pitch blade link? If there is no adjustment than having the pitch slider dead center means nothing.
Ace,

Please reread my last post. I DO HAVE adjustments in my tail. First you center the tail pitch slider, next you adjust the tail links that attach to the slider to set the tail to the proper pitch so when you hover it holds in normal mode. Also each tail blade is individually adjustable so you can also adjust tracking.
Its logic or common sense to some people. If you don’t pay attention to headspeed then the control is biased to one side always making up for a torque that shouldn’t be there. Probably the only place that you will witness the ill effects is on spool up when some helis will kick in one direction or the other just before lift off and then come back to where the gyro was initialized. If you are happy with that behavior then I guess it doesn’t matter
It may make common sense to you. Again what you say makes no sense. Assuming you have your Gryo turned on, it compensates for torque load. When you lift off torque changes based on weight, wind and the amount of lift off pitch given. Torque load is different every time you take off. Headspeed isn't a factor in Gryo control unless you are running a headspeed so slow your tail doesn't have enough authority to hold position. If you are in HH mode there will be no kick in either direction upon lift off because it will control it (that's the purpose in the first place) So let's not come up with something that has nothing to do with setting up a Gyro correctly.

Lou

Twin Bergen 44Magnums FBL Wren NW44s - Kero start

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11-29-2007 09:07 PM  9 years agoPost 52
AceBird

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Utica, NY USA

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Lou you told me you were an Engineer and now I am beginning to wonder. This is not that difficult a concept to grasp for an engineer so I will leave it to those that understand and you can do whatever.

Ace
What could be more fun?

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11-29-2007 09:38 PM  9 years agoPost 53
lperagallo

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Westfield, Indiana, USA

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Ace,

I've said I am NOT an engineer. I think you have me confused with Excaliber.

lou

Twin Bergen 44Magnums FBL Wren NW44s - Kero start

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11-30-2007 02:40 AM  9 years agoPost 54
Chopper Man100

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Canton GA.

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I agree with ACE on the head speed issue from experience. All the guys I help, I always inform them to get your head speed right before finalizing their tail rotor setup in normal mode. I don't know how many of you have set up heli's back when we had nothing but mechanical gyro's. If you set up some older machines with the older gyro's, you should be familar with this concept. It always took a little more patience to get it setup right by first getting the head speed correct. If you changed your head speed around, there was always some readjusting on the tail rotor setup (slight). The new head holding gyro's cover up this problem. On the none head holding gyro's, after you get the hovering setup, they you get to adjust your revolutionary mix to get it right, oh what fun they use to be.

Haven't you noticed, if you run a higher head speed, the tail rotor is much more sensitive and powerful, and sometimes you have to decrease your gain because of it. This is kind of an off subject and not totally related to the point of what ACE is trying to get across, but it does play a factor in it. We could get really deep with this subject but I don't have an hour to type it all out. The bottom line is, the tail rotor reactions and actions are related and effected by head speed. Again, the facts that I am bring up are not exactly what ACE is trying to say but maybe it will help some people understand that head speed does effect the tail rotor and its setups.

Just to be clear, all the above information is more relivant to a conventional gyro, not HH. All the gyro's I have setup, the instructions state to get it setup as best as possible in conventional mode first before using HH mode.

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11-30-2007 03:38 AM  9 years agoPost 55
sla

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wasilla,ak,99654

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still not exactly right. i have done everything right. the gears in the tail might be a little to loose. the gears are supposed to be pretty snug if i am not mistaken. right now there is actulaly a little slop. so i ordered new ones. i think they could definatley cause the drift im sure. i am sure i was in hh but just for fun tomorrow i will check it, you never know.

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11-30-2007 03:58 AM  9 years agoPost 56
FCM

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Surrey, England

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The modern solid state tail gyros is effectively two gyros together. It will serve everybody well to remember this as trimming in normal (rate) mode is seperate to heading hold (AVCS)mode.

A change in head speed will make a difference in normal mode but unless the change is very large (very high or very low) it will not affect the heading hold mode.

Paul.

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11-30-2007 05:11 PM  9 years agoPost 57
AceBird

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Utica, NY USA

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I've said I am NOT an engineer.
I stand corrected, I did confuse you with Excal.
i am sure i was in hh but just for fun tomorrow i will check it, you never know.
Sla, does the 601 display what gain level you are at? You could be in HH but if at a very low gain it might drift. My only other guess would be vibration problems and how the sensor is mounted as unexplained phenomena. I think for you one of the problems with the 601 is how many features that this gyro control has. None of those other features have been discussed here either because people are not familiar with them or no one that is using this gyro has commented.
All the gyro's I have setup, the instructions state to get it setup as best as possible in conventional mode first before using HH mode.
I interpret that these instructions make an assumption that when you do this the headspeeds are the same for both, otherwise why do it. You are trying to find the center position of the servo that results in equilibrium and that changes with changes in headspeed.
but unless the change is very large (very high or very low) it will not affect the heading hold mode.
Paul, if it affects it, it affects it. You are only talking the degree of influence. You could cop the same attitude about the whole mechanical set up if you are going to let the gyro compensate for any imperfections. Heck, throw the servo and linkages on were ever they end up and let the gyro fix it. Isn’t this the same logic? Just worry about getting the directions right and you’re good to go. That’s not for me.

Ace
What could be more fun?

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12-01-2007 01:52 AM  9 years agoPost 58
FCM

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Surrey, England

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Paul, if it affects it, it affects it. You are only talking the degree of influence. You could cop the same attitude about the whole mechanical set up if you are going to let the gyro compensate for any imperfections. Heck, throw the servo and linkages on were ever they end up and let the gyro fix it. Isn’t this the same logic? Just worry about getting the directions right and you’re good to go. That’s not for me.
Read the whole of my post. The only way that a change of head speed can affect AVCS mode is if the tail rotor is running too slow to counteract the torque. If it is too fast and I am talking way too fast here, it may induce enough vibrations to affect the gyro sensor.

Trimming the normal mode will not fix any issue with AVCS mode. This is another way of putting it. If you are not getting a tail lock in the hover in AVCS mode then you have an issue probably one of the following:

Gyro reversed.
Tail servo failing.
Gyro sensor failing or failed.
Grossly out of mechanical trim i.e. pitch slider unable to move sufficiently to cope with demanded pitch.
Vibration affecting the gyro sensor.

Paul.

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12-01-2007 05:28 AM  9 years agoPost 59
sla

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wasilla,ak,99654

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another set of eyes looked at the tail gears and we think in a hover they vibrate just enough.

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12-01-2007 02:13 PM  9 years agoPost 60
AceBird

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Utica, NY USA

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Trimming the normal mode will not fix any issue with AVCS mode.
If I said this or implied this I didn't mean to.

Trimming in normal mode AFTER the HH mode has been balanced is to make up for the slight variation in torque (assuming different headspeeds) going from HH to normal.

Trimming in normal mode FIRST is to find the balance point of the HH mode. In this first exercise both headspeeds are the SAME.

You missed a hugh one Paul:

Not understanding the programming of the gyro and the radio that you are using. I think this happens most often.

Ace
What could be more fun?

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