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HomeRC & Power✈️Aircraft🚁HelicopterFlybarless Rotor Head SystemsFutaba CGY › Rate Mode Tail (Normal) setting
06-01-2011 02:40 PM  9 years ago
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mcoccia

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Rate Mode Tail (Normal) setting
Guys,

We should be setting the tail up in normal mode? I ask this because I know it's the right way or atleast it used to be. The problem I have is the manual tells you should have = throws on both ends but my Gaui X5 will not have this if I adjust her.

What is the right way? I'm leaning towards setting it. I did notice my tail servo get pretty hot and I am no 3D pilot

Thanks guys
Mark
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06-01-2011 03:31 PM  9 years ago
Wyorcflyer

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Cheyenne, Wyoming USA

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To set normal mode or not! Get the popcorn.

The manual provides a set up process. On page 63 of the CGY750 manual it provides "When Using AVCS mode the optimum setup is to have 0 degrees of pitch with the tail rotor servo centered and use all all of the available pitch range in the tail without binding" It concludes with "If you are going to fly AVCS Heading Hold mode exclusively, then the rudder gyro setup is now complete".

The manual further provides on page 69 for a 10 degree blade pitch with the servo centered if you want to fly normal mode.

Some say that you should use the normal mode setup even if you are going to fly exclusively in AVCS mode. Futaba does not seem to think so.

At any rate I don't use normal mode on the tail and I have set up my GY520s and my CGY750 per the instructions with 0 Degrees of pitch at center and they work great. Therefore the answer seems to me to be either will work so take your pick.

Maybe Dr. Ben can get a confirmation from Futaba!

Jack
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06-01-2011 04:25 PM  9 years ago
BisonFlyer

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Absolutely set the tail in normal mode so it does not drift at all at your normal flying headspeed.

If your endpoints aren't correct its because the geometry on the tail on that particular heli is incorrect. On any properly designed helicopter there should be around 6-8 degrees of right rudder with the bellcranks/linkages at 90 degrees.

Anyone that tells you setting it in normal mode isn't necessary (and there are a lot of them out there, haha) isn't able to push the tail hard enough to notice the differences. Its a huge difference in performance on every gyro i've ever flown when its mechanically correct in normal mode.
Art Hughes
SAB Heli Division~Byron Fuels~Mikado V-Team~Scorpion~Pulse~Xpert Servo~Kontronik Drives
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06-02-2011 02:20 AM  9 years ago
Wyorcflyer

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Anyone that tells you setting it in normal mode isn't necessary (and there are a lot of them out there, haha) isn't able to push the tail hard enough to notice the differences. Its a huge difference in performance on every gyro i've ever flown when its mechanically correct in normal mode.
Art:

It is Futaba right in their manual that says to set 0 degrees at center if you are only using AVCS. One would hope the designer of the unit would know how to set it up!

Oh and thanks for telling me I suck, but I already knew that.

Jack
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06-02-2011 07:23 AM  9 years ago
BisonFlyer

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lol.... I did not mean to imply that you suck Jack. After re-reading my post though I understand why you thought that after what you posted. That was not my intention though, and I apologize for it sounding the way it did.

I have no problem with what you wrote (just saying that the manual says one thing, some guys say the opposite, and you set it up per the manual and it works fine for you).

Unfortunately the manual isn't helping users get the maximum performance by outlining the tail setup the way it does. In heading hold it will work without being trimmed in normal mode. By work, I mean that it will fly around and track correctly without blowing out for moderate sport/3d flying. However, to get maximum tail holding power and piro consistency, trimming it in normal mode is very important. Without proper mechanical setup, the holding capability of the gyro is significantly limited. If you are flying advanced piro maneuvers or really pushing the tail with backwards/sideways flight, you will notice a significant difference between a proper mechanically trimmed tail, and one just set arbitrarily (or for 0 degrees at center stick).

If you are not having any tail issues, then by all means, just go with the current setup. If you'd like to know you are getting the most performance from your equipment however, i'd strongly recommend tracking the tail in normal mode and ensuring proper tail geometry between your servo and any bell-cranks that may be in the equation.

I wish the manuals for all the RC equipment we use gave the best setup advice to maximize performance for 3d flying, but unfortunately this is normally not the case.

Again I apologize for the way my original response sounded after your reply

Hope that helps!
Art Hughes
SAB Heli Division~Byron Fuels~Mikado V-Team~Scorpion~Pulse~Xpert Servo~Kontronik Drives
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06-02-2011 04:29 PM  9 years ago
Wyorcflyer

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Art:

No problem mate! I commend your professional response.

This is an issue that can only be resolved by knowing the programming code. It is quite possible that the code in the unit is written so that the unit functions properly using either of the setup processes provided in the instructions. Hence the instructions may in fact be correct. I don't know the code and therefore don't know the answer.

It would be helpful if Futaba would stick a fork in this issue by chiming in with a response. If their instructions are not providing the optimal setup they should be revised or they should note that method B provides a better result than method A.

There is a practical issue here for many of us that live in cold climates. The setup process provided for AVCS only, setting center at 0 degress, can be done in the comfort of the man cave on a cold day. Many of us have lots of cold days to do that. Since most of us use only AVCS mode that would take care of setup. Trimming for normal mode flight cuts into our limited and precious flight time. There is therefore a significant benefit to many of us if the instructions are correct and a 0 degree center setup is as good as triming in normal mode.

Just my 2c.

Jack
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06-02-2011 04:44 PM  9 years ago
BisonFlyer

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I can assure you that setting it up in normal mode yields significant benefits when flying in AVCS mode exclusively. This is confirmed by the rest of the Team Futaba pilots that actually do the testing on the unit before it is released. It only takes a minute or two at the field to do it so again, i'd encourage you try it. If the helicopter has correct tail geometry, setting the bellcranks up at 90 degrees should yield the proper 7ish degrees of right rudder so it would be good directly from the bench setup.Art Hughes
SAB Heli Division~Byron Fuels~Mikado V-Team~Scorpion~Pulse~Xpert Servo~Kontronik Drives
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06-02-2011 05:08 PM  9 years ago
Wyorcflyer

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Art:

I am not an advocate here. I don't know the answer. I have set up GY520s both ways and could not tell but that may because I am not as proficient as you are.

lets do a blind test. I will offer my Fury 55FBL with CGY750 as a test bed. We will test fly with a 0 degree center on the tail, per the instructions, and with an offset center trimmed for normal mode, per the instructions. We can both fly it each way but of course only in AVCS mode.

The trick of course will be that we will need a third party to do the setup so we won't know which setup is which. Then we can see if either of us can tell the difference and whether we can see the difference in flight performance.

Are you up for it?

Maybe at the Heliproz Funfly?

Jack
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06-02-2011 06:03 PM  9 years ago
Dr.Ben

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Here's the deal.

Dating back to the time of the 611/401 and even back to the GY501, guys had gotten pretty lazy with tail set up. Anyting remotely close to anything in center of travel for t/r position in AVCS for the most produced tolerable results. Understand too that these earlier products have nowhere near the piro consistency or hold of the 520 and later gyros both single and three axis. It was amazing enough in the early days to have the tail just stay put in a long and fast tail slide.

Now fast forward to the release of the 520. The manual did/does indeed say to center the system arounf 0 degrees of t/r pitch. During the pre release testing of the 520, it became apparent that the 520 was not pirouetting or holding as well as everyone thought it should or could. So, the recommendation came from Japan to make sure to have the tail rotor first trimmed out in rate mode at your approximate flying headspeed. With this change, the piro consistency and hold of the gyro improved markedly. I personally never felt the difference from one set up method versus the other because I've never done anything but first trim out in rate mode knowing full well that a poorly trimmed tail just isn't ever a good thing. That said, it's not a hard argument to explain that flying a tail that is out of mechanical trim makes work harder for the gyro as it compensates for the trim error and differential offset in the servo arm that that error creates. I've described this in exhaustive detail in posts in the past when this question has come up. I would agree that it would be clearer if the manual were revised to reflect this most current information. All theory and practice for t/r set up that proved to be applicable for the 520 has been carried over to the 701 and 750. And BTW, it applies to the cyclic control gyros as well.

Art had mentioned that these techniques are critical the best performance in 3D. I would submit that a well set up tail works the best for ANY style of flying just as a powerful and smooth running engine is the best fit for anyone's needs. Regardless of discipline, we're all after a vice like grip of the gyro on the tail and a consistent piro rate.

Ben Minor
Peak Aircraft/Team Minicopter Team Futaba Team Kontronik USA
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06-02-2011 07:10 PM  9 years ago
BisonFlyer

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Thanks for chiming in Ben. And Jack i'd be happy to join you on your test if I am able to make it to the Heliproz FF . I have accidentally flown my machines without trimmed tails after rebuilds etc, so I already know the results . Not realizing it wasn't trimmed I did my normal flying and was immediately thrown off by how bad the tail was... brought it back into a hover and clicked into normal on the gyro to find that it was out of trim. My info wasn't just based on theory, but in flight differences that are dramatic. I've been caught by it as well on my setups when not resetting correctly.

Unfortunately though, as Ben stated... the manuals have not been updated to reflect the proper setup. This seems to happen a lot in the hobby . Thats why the forums are great though so guys can get updated information on the correct methods that might be missing from product manuals.

And as Ben stated, proper mechanical setups should be performed for any style of flying, even if the differences might not be dramatic for normal sport flying.
Art Hughes
SAB Heli Division~Byron Fuels~Mikado V-Team~Scorpion~Pulse~Xpert Servo~Kontronik Drives
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06-02-2011 07:54 PM  9 years ago
Wyorcflyer

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Thanks Ben and Art.

As both of you note it is important to have the tail properly set up. The question is what is a proper set up? Manual protocol A or B? You both say B and I will accept your word for that.

I will trim out my Fury 55 CGY750 in normal mode and see if I can tell the difference. I am probably not far off. I have to confess I set my Fury 55 up so that it was mechanically neutral at center so it is closer to 7 degrees at center than to 0 degrees at neutral since the tail slider geometry is not symetrical. Since the tails are set up for more right pitch than left 0 degrees at center would result in a significantly different resolution to the right and left.

Jack
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06-02-2011 07:59 PM  9 years ago
BisonFlyer

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Yep the 55 has a properly designed tail geometry so if you set it with your bellcrank at 90 degrees, you have roughly 7 degrees right rudder already. My guess is you are no more than a turn or 2 off from perfect mechanical trim already. Get it trimmed perfecly, fly it around, then set it to 0 degrees at center, and fly it around again (if you really want to see the difference). My guess is you'll notice the difference fairly quickly with a bad mechanical setup.Art Hughes
SAB Heli Division~Byron Fuels~Mikado V-Team~Scorpion~Pulse~Xpert Servo~Kontronik Drives
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06-02-2011 08:56 PM  9 years ago
wbplomp

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For me it is simple. I always try to get an equal tail pitch limit like 100/100. By the way, according the manual everything between 90-110/90-110 is considered to be ok. If the geometry on the heli already has a bit of throw at center, that is fine. But when it doesn't I am not going to change that. I don't want to much unequal limits. And your tail servo arm should not pass a 45 degree angle. Ofcourse I frefer a bit throw already present on the pitch slider. But all my models just don't have that.

In the past I have tried both on a lot of T-Rex setups. It did not make much difference on most models/setups. And sometimes if I did it it introduced another issue in flight. I onced e-mailed Angelos from Spartan about it. He mentioned it is not neccesary when you only fly in AVCS mode (for the ds760 though). It is even written in their FAQ. I know some 3D pilots (e.g. Bert Kammerer) trim it mechanically.

If you want to apply it. Then may I advice to use trim. You then keep equal limits and don't pass the 45 degree angle on your tail servo arm.

I have one excuse right now. The trim on my Tx for rudder is broke.
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06-02-2011 09:14 PM  9 years ago
BisonFlyer

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Yep Spartan claimed it wasnt necessary either which was also misleading. Take a 760 or a quark, have the normal mode trim off by a significant amount, then take it into a hover in heading hold and the model will actually slowly piro while stationary in heading hold. If the claims that the mechanical center doesn't matter for AVCS were true, that would not be the case.Art Hughes
SAB Heli Division~Byron Fuels~Mikado V-Team~Scorpion~Pulse~Xpert Servo~Kontronik Drives
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06-02-2011 09:17 PM  9 years ago
wbplomp

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I don't say it ain't true. It just say it does not make very much difference on most recent gyro's. Keep in mind it is software as well.

By the way, almost every T-Rex has a semetric tail pitch slider. The manual states center. Nobody at our club has what you discribe. What you are saying isn't a fact. No fence.
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06-03-2011 02:32 AM  9 years ago
mcoccia

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Looks as I opened a can of worms...LOL!!!

Thanks for the posts. I am going to trim her out in Rate mode, from past experience that appears to be the right way.
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06-03-2011 04:22 AM  9 years ago
Wyorcflyer

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Art and Ben:

You asked for it you got it. I tested the Fury 55 with CGY750 this evening with the tail configured using both of the methods described in the manual.

Conditions
Altitude: 6200’ msl; 9000’ density altitude. (Really!)
Temp 84°
Wind W10-15 first flight, 8-10 second flight.

Setups:
1. AVCS only mode. This is the setup from page 63 of the CGY750 manual. It took 6 turns on the linkage to get from this setup to the Normal mode setup below. That will vary from heli to heli.
-----a. Tail blades at 0° with the rudder servo centered and servo arm dead perpendicular to the control rod.
-----b. CGY750 servo limits in rudder basic A (Left) 87%; B (Right)137%.

2. Normal mode. This is the setup from page 69 of the manual. I flight tested the heli and adjusted the rudder linkage until the model hovered without pirouetting at center stick in normal mode. No trim or sub trim. The setup I had originally was closer to this setup but did not have quite the same differential between left and right servo limits. I think the difference was 8 points instead of 15. I think I only turned 1 turn to get from my previous setup to flying in dead center normal mode.
-----a. Resulting blade pitch at center 7°-8°. Tail bell crank exactly perpendicular to the boom.
-----b. CGY750 servo limits in rudder basic A (Left) 115%; B (Right) 100%.

Flight test:

I did everything I can do with both setups. Piro flips, fast straight line piros both upright and inverted, Piro circles, hurricanes, flips, rolls, stationary pirouettes fast and slow, funnels, tail slides, rolling tail slides, tic tocs, autos, ok you get it.
I could not tell a bit of difference. The tail acted the same both ways. Piro rate was consistent whether stationary or moving or into the wind or down wind. The tail always did exactly what I commanded it to do. No hint of blow out or failure to hold even in a 300’ tail slide.

One surprise was that I did switch to normal mode with the AVCS only setup. The heli did pirouette with neutral stick but not nearly as fast as I expected. It was easily controllable, not that I would ever want to fly in normal mode again.

Conclusion:
About all I can say is that this thing is about as idiot proof as it could be. About the only thing I could see to judge between the two is the servo limit differential. 87% to 137% is a lot of difference. At some point you would think the programming may struggle to make up for too much differential. The normal mode setup supported by Art and Ben is going to be much closer to having equal limits in most helicopters.

The good news – Either setup seems to work. There is no obvious difference, to me anyway. The bad news – Without really seeing the code and having it explained it is difficult to know if it really matters. Having said that, I will personally not accept a setup that has a huge differential between left and right servo limits. That may change what you setup for center pitch if you have a mechanically symmetrical bell crank like the T700 that at center bell crank has 0° of pitch. For classic tail pitch setups the normal mode approach should give pretty similar left right servo limit settings with a bell crank that at neutral provides about 7° of pitch like the Fury55, T600, SDX etc.

The really bad news: I am becoming a convert. This is my first FBL and I already prefer it to the Fury 55 before I converted it and to my two best flying current FB helis, the T700 and the SDX. Dang, it is sure expensive to convert and you end up with a bunch of orphaned parts and electronics. Anybody want to buy a FB heli? Mac and Cheese here we come.

Yes, Art, if you are around for the HP Funfly I will take you up on doing a blind test of both setups. Should be interesting. Reminds me of my college days and blind tests of Coke, Pepsi, RC Cola etc.

Jack
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06-03-2011 08:08 AM  9 years ago
wbplomp

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Thanks Jack! Good testing and great explanation. Actually, just as what I expected. I think I was quite close to your conclusion. Of course different setups may vary.
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