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HomeAircraftHelicopterRadio - Servo - Gyro - Gov - Batt › HH Gyro Question (Futaba)
11-18-2011 02:53 PM  6 years agoPost 1
iskoos

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Orlando, FL

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This is mainly for Futaba HH gyros because I have seen the same paragraph on every Futaba gyro manuals. This makes me think that this applies to Futaba gyros specifically but I believe I saw the same thing on Spartan gyro manual as well...

Anyways... The question is:

Why does the system have to be powered up at HH mode?

Why is that so important?

What's wrong powering the system at normal mode and then switching to HH mode and fly?

I have powered up my helis in the past in normal mode many times and then switched to HH mode and flew. They all flew just as good...

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11-18-2011 03:39 PM  6 years agoPost 2
Pistol Pete

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Seffner, FL

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If I had to guess (which I am), I would say it has something to do with learning the Tx center stick position as a reference starting point. Then again, I have been wrong "once" before.

I would follow manufacturers directions to be on the "safer than sorry" side.

~~Enjoying the hobby one flight at a time~~

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11-18-2011 05:16 PM  6 years agoPost 3
iskoos

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Orlando, FL

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Thank you Pete What the gyro reads from Tx during the power up is the neutral rudder signal. And as far as I know the rudder neutral signal from the Tx (as long as no trim or rudder input given) will be the same for both Normal (rate) or HH modes. So I cannot see this to be the reason. There is got to be another reason which I hope somebody could explain to me.

I follow manufacturers directions too (Most of the time) but I would also like to see good explanations. Futaba gyro manuals have some confusing paragraphs which I could never understand.

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11-18-2011 10:50 PM  6 years agoPost 4
GMPheli

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W. Bridgewater, MA USA

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I agree the software could be written so it does not matter what mode it is booted in. However, the manufacturer did not do it this way. It probably required more code, and they thought that booting in HH only is just not that big a deal. Older gyros (Arcamax for instance) did not memorize the neutral setting. They came through preset and I don't believe it mattered what mode you booted up in (I always booted in rate). On these gyros, you would trim for no drift in HH, and then adjust the pushrod for no drift in rate. Not that this really pertains to your question, just some trivia.

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11-19-2011 04:34 AM  6 years agoPost 5
Pistol Pete

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Seffner, FL

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There may be no difference, in some models, how its started but taking off in HH avoids a tail kick, specially if not trimmed correctly for Rate mode.

~~Enjoying the hobby one flight at a time~~

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11-19-2011 06:12 PM  6 years agoPost 6
iskoos

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Orlando, FL

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Well, actually taking off at HH mode might cause a tail kick if the helis yaw rotation has changed and gyro hasn't been reset...
That's why most of the time I either reset the gyro before spool up or I turn it on at non-HH mode and switch to HH right before take off...

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11-21-2011 12:23 PM  6 years agoPost 7
iskoos

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Orlando, FL

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I guess majority doesn't know the answer to my question.
Believe me if I knew I would get an answer by calling Futaba, I would do just so. But I know they won't be able to tell me anything more than what it says in their instruction manual...
Will keep searching...

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11-21-2011 12:45 PM  6 years agoPost 8
BarracudaHockey

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Jacksonville FL

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I'm surprised Ben hasn't chimed in.

A true answer would probably require detailed knowlege of the firmware on the gyro and I doubt too many people outside of Japan have it.

Andy
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11-21-2011 01:16 PM  6 years agoPost 9
z11355

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New England

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The code is written so the gyro 'learns' the mid-stick pulse width upon initialization. There can be slight variation unit-to-unit (tx) and brand to brand (isn't it 1.52 vs 1.50mS between Futaba and JR?)

As I recall, the JR5xx also had a fixed notion of center and it required rudder trim correction too.

I think you stand a better chance of getting an answer from Spartan since Angelos actually writes the code for the Quark/DS760

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11-21-2011 05:54 PM  6 years agoPost 10
GMPheli

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W. Bridgewater, MA USA

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It could be that if the gyro is not booted in HH, then it will just revert to the last center position. In any event, does it really matter? Why is having to boot it in HH an issue?

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11-21-2011 11:07 PM  6 years agoPost 11
iskoos

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Orlando, FL

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Hey guys...

Barracuda, A pm sent to Ben last week with a link to this thread requesting his input. I did search the older threads and found out Ben Minor is very knowledgeable on Futaba systems but I haven't gotten any reply so far...

z11355, What you are saying might be an answer to why HH gyros need to read the neutral signal at each bootup because as you said different brands might have slightly different neutral signal and this difference might cause a problem. But in my question I was asking why the gyro needs to bootup in HH mode instead of Normal (Rate). So neutral (mid-stick) signal in HH mode is same as the neutral signal in Normal mode (speaking of the same Tx unit). Good point though; thank you but not the answer I was after However, I might take your advice on contacting Angelos if I can't find an answer soon. Spartan gyro manual was like a cc of a Futaba gyro manual He might enlighten me...

GMPheli, I doubt that HH gyros that are setup to read neutral signal at each bootup will remember the previously used neutral signal if they don't receive a valid one.
And your question "why does it really matter?" The simple answer is that I would like to know why. That's pretty much all... There is nothing more to it. Due to some challenges I had to face with recently while setting up different gyros, I wanted to learn exactly how they function. That's all...

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11-21-2011 11:27 PM  6 years agoPost 12
Phaedrus

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S. Orange County, California

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Not sure about that, and if it is true (must be powered up in HH (AVCS) mode) then I have been doing it wrong.

Here is what the GY-520 manual says:
• The GY520 requires 5-10 seconds to initialize when the power is turned on. Do not move the helicopter and do not move the tail rotor stick during this initialization or the gyro may not initialize properly. Once the initialization process is complete, the tail rotor servo will move to the left extent and then to the right extent. This will occur twice. The indicator light will change to solid blue for AVCS Mode or solid red for Normal Mode.
Where have you seen that Futaba HH gyros must be turned on in HH (AVCS) mode?

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11-22-2011 12:42 AM  6 years agoPost 13
iskoos

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Orlando, FL

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Well this is great. I do not have any recent Futaba gyros like 520 or 701 but I used many of the previous ones like 401, 502, 601 and 611. I was so sure that it would be in each of these manuals. So I started looking for it. You know whenever you are looking for something you can't never find it. And you don't look for it, it appears every moment... I checked different manuals for about 30 minutes and I couldn't find where the heck I saw that. But the funny thing is that while searching for it, I found something else which could almost be an answer to my question. The page 30 of GY 611 manual says (Under the paragraph tittled as [At Power ON]):

- When the power was turned on in the Normal mode, the rudder neutral position already memorized in the GY611 is not updated.
- When the power was turned on in the AVSC mode, the rudder signal at that point is memorized and updated.

This technically a perfect answer to what I am asking but it brings another question: If I am kind of a pilot who always flies in Normal mode and makes a trim change on the Tx before powering up my gyro unit (in Normal mode), then the gyro will not see the recent trim change!..

Well anyways, I am sorry guys if I confused you but I did see what I said somewhere more than ONCE. I will find it and when I do, I will reference it. I am thinking now maybe I saw it in some online articles about HH gyro setup and I thought it was said by Futaba. If so, my apologies go to Futaba but I still do think that I saw this on some official Futaba prints somewhere... I will look more...

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11-22-2011 12:47 AM  6 years agoPost 14
Phaedrus

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S. Orange County, California

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I have a couple of 611 gyros. If you power up in rate mode (normal) and then switch to HH you have to allow the gyro to recenter. See page 31 of the 611 manual for details.

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11-22-2011 12:57 AM  6 years agoPost 15
BarracudaHockey

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Jacksonville FL

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z is 100 percent correct. During initialization of Futaba gyros they memorize the center pulse because it can differ between brands and sometimes between transmitters of the same brand slightly. This is why gyros like the 770 usually need some subtrim tweaking.

Andy
AMA 77227
http://www.jaxrc.com

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11-22-2011 02:22 AM  6 years agoPost 16
iskoos

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Orlando, FL

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Phaedrus, I guess pretty much all previous HH gyros like 401, 601, 502 have the same function that you were refering to at page 31.
I did power up my 611 at Normal mode and then switched to HH and flew. I didn't notice any difference. I did NOT do the rereading of the rudder neutral position because I did NOT do any rudder trim change.

Barracuda, I didn't say z11355 (if that's what you mean by "z" ) was wrong. I just said that what he said would be a good explanation to why the rudder neutral signal needs to be read at each power up. And I aggree with that... If 1.52ms programmed to gyro as a fixed rudder neutral and if the Tx transmits 1.50ms instead of 1.52ms, then the gyro might see that small pulse difference as a rudder input and this might cause a problem. I have no objection to that.
My issue was why the gyro needs to be powered up at HH instead of Normal and as I stated in my previous post, that page 30 of the manual GY611 answers it. It looks like whoever wrote the code made it so that if the gyro powers up in HH, it would update the neutral rudder signal but if it powers up in Normal mode, it would NOT.

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11-22-2011 05:29 AM  6 years agoPost 17
PilotPin

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Indiana -- USA

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I have a Futaba GY401 an remembered the same thing about it. Under the (Monitor LED display) intermittent flash -- Alarm display when the power was turned on in the normal gyro mode. For the rudder neutral signal to be read correctly, set the transmitter to the AVCS mode and turn on the gyro power again.

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11-22-2011 07:12 AM  6 years agoPost 18
Phaedrus

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S. Orange County, California

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That may well be for the 401 and older. From the 401 manual:
When turning on the power, set the transmitter switch to the AVCS position and turn on the transmitter power switch, then turn on the gyro power.
This is not the case for the 611, 520, 701 and 750. Those can all be turned on in either rate/normal or HH/AVCS

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11-22-2011 11:37 PM  6 years agoPost 19
iskoos

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Orlando, FL

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Thanks and yep... I saw it in 401 manual and more than once. it says again at end of page 2 under "Flight Adjustment" under Step (4)...

It has been a long time since I read 401 manual. I read "Flight Adjustment" section again and it made lots of sense this time.

I still think that I will find similar paragraphs in 502, 601 and 611 manuals...

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