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HomeAircraftHelicopterRadio - Futaba FASST › tail drift and gy401
08-10-2010 12:07 AM  8 years agoPost 21
CX1

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Canada

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Will you please go out and hover for 60 seconds without touching the rudder and tell me the tail still points in exactly the same direction
ok it holds the heading (no drift) even with wind

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08-10-2010 12:43 AM  8 years agoPost 22
LonR

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Macomb,Mi

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Hamo
Will you please go out and hover for 60 seconds without touching the rudder and tell me the tail still points in exactly the same direction.
Hamo
If yours doesn't then you need to set it up right because a GY401 will hold like a rock all day long.

600LE,OS55,OS PowerBoost pipe,Align 610's,Spartan

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08-10-2010 01:00 AM  8 years agoPost 23
Aaron29

rrProfessor

USA

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Will you please go out and hover for 60 seconds without touching the rudder and tell me the tail still points in exactly the same direction
Really?...

https://rc.runryder.com/t522423p1/?highlight=401+hold

Hamo, we went through this before in the above thread like a year ago! Shall we repeat the experiments so you can challenge us again next year? You stubbornly didn't believe us then, so why would you now?

Please. Something is wrong with your gyro or setup or something. Stop making blanket statements about gyros based on yours. It'll just discourage the OP from working to get an optimal setup.

Drifting is not normal and is not something anyone should just accept.

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08-10-2010 02:42 AM  8 years agoPost 24
mlucia

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Essex Jct., Vermont

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You should go through everything because that gyro will not drift when setup right
+1

Chances are you have added trim or subtrim and now the gyro does not know center. Simply double check trim and subtrim, set to 0 if there is and then starting in HH mode toggle the switch that the gyro is on from HH to rate mode 3 times landing in HH mode. This will reset center.

The 401 will not drift at all when setup correctly.

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08-10-2010 09:05 AM  8 years agoPost 25
Hamo

rrVeteran

Ireland

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You stubbornly didn't believe us then, so why would you now?
Sorry but I believe my own eyes before I believe someone else's statements even if they are endorsed by 100 other people.

I am able to rotate the helicopter slowly on the table and after 90 degree rotation there is no change in the tail blade pitch. If I make any sudden moves, the gyro responds by changing the blade pitch.
That's all I am saying.

I have 2 friends who both told me their 401 held like a vice, I met them at the field and said OK, show me, hover without touching the rudder and they were both surprised they couldn't and didn't realize they had drift because they never hover for any length of time.

I will have to accept that there must be some differences in the 401s you guys are using. Maybe the one I have is a counterfeit, not a genuine 401, don't know, sorry if I annoyed anyone.

Hamo

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08-10-2010 02:59 PM  8 years agoPost 26
Aaron29

rrProfessor

USA

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I'm not offended. I just think you need to rethink what is normal for a gyro.
Sorry but I believe my own eyes before I believe someone else's statements even if they are endorsed by 100 other people.
But speaking of offense...If the above quote is your approach, no offense but why did you ask him to do the experiment if you are going to ignore the result?

For grins, I'll probably try a 60 seconds hover test next weekend. But if I post my results here, will you believe them? Because based on how you have run your experiment to date, I have no reason to believe you will accept whatever answer I give unless it coincides with your held belief!

And just how much until we call it drift? If I hover for a minute and it changes heading maybe 10 degrees can we call that vice hold? I would. That to me is pretty much solid and can be attributed to the tiny cyclic changes you make.

Yes, you can change heading with cyclic alone.

An extreme example to illustrate how cyclic can affect heading would be to pretend you put right cyclic until the heli is knife edge, and then you can change the heading with elevator, and put left cyclic until it is level again. Obviously you won't do this much bank while hovering, but it illustrates the effect. Use of elevator when the heli is banked will change heading, however slight.

So how many degrees per minute is considered drift for this experiment?

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08-10-2010 03:31 PM  8 years agoPost 27
BarracudaHockey

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Jacksonville FL

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Chances are you have added trim or subtrim and now the gyro does not know center. Simply double check trim and subtrim, set to 0 if there is and then starting in HH mode toggle the switch that the gyro is on from HH to rate mode 3 times landing in HH mode. This will reset center.
eh...not really

If you add trim or subtrim then flip the switch 3x or power cycle the gyro, then it accepts that as center including the trim or sub trim. Thats the main reason you dont have to fuss with subtrimming the drift out of Futaba gyros, because they know that all radio systems don't have the exact same center pulse width.

Now......adding trim and changing flight modes can cause a problem with radios that have trim per flight mode. But sub trimming a small amount to get the servo arm at 90 degrees won't hurt anything.

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

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08-10-2010 03:46 PM  8 years agoPost 28
Aaron29

rrProfessor

USA

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I recommend the rate mode mechanical setup. Some don't, but I do it and have always had good results. Besides, it's easy enough to do, so why would I stop?

You basically start out in rate mode with no rudder subtrim or trim of any kind.

Hover it. Set gain as high as you can go until you get a quick wag and then back off until the wag is gone.

Then hover it again, nose pointing into the wind. If it drifts, do not touch the trim. Note which direction you are having to hold on the rudder to keep it still. Land, and lengthen or shorten the control rod to mechanically alter the neutral pitch of the blades. Keep the trim centered.

You'll do this a few times, and get to a point where it stops drifting. Then you can really fine tune it by observing what happens when you put each side into the wind. If setup correctly, it should turn on its own into the wind, weathervaning, if you will.

If it seems to favor a side when you place it sideways to the wind, you can change the rod length until it doesn't favor a side. Then you know it is mechanically set.

Then set the limits so that there is no binding. Then set rudder ATV for your desired rotation speed.

Then switch to HH and it should hold like a vice.

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08-10-2010 04:52 PM  8 years agoPost 29
Hamo

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Ireland

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So how many degrees per minute is considered drift for this experiment?
My point is, based on my experiments on the table top, I can rotate the helicopter 90 degrees in one minute and the gyro does not see it.
If this rotation was caused by a light breeze, the effect would be the same.

Aaron29, I agree with you 100% on the need for mechanical setup. This is more or less what I do. I hover in rate mode and keep adjusting the rod length till there's no drift, then switch to HH. I will take your advice on putting each side to the wind during setup. Thanks

Hamo

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08-10-2010 05:15 PM  8 years agoPost 30
BarracudaHockey

rrMaster

Jacksonville FL

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I wont drag this into another debate other than to say, center the servo, center the tail pitch slider works just as well. The rate mode setup only works for that exact RPM. Change the power requirment, even slightly, and the tail rotor compensation requirement changes.

Either way works though, and there's always more than one way to skin a cat.

Hamo, put your finger on the tail pitch change mechanisim, I suspect the gyro is compensating you're just not seeing it.

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

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08-10-2010 05:18 PM  8 years agoPost 31
Aaron29

rrProfessor

USA

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Change the power requirment, even slightly, and the tail rotor compensation requirement changes
Yup, so really you are only optimizing it for the headspeed you did the setup at. Still, I've had great results doing this, so I do believe it is more effective than a rain dance.
My point is, based on my experiments on the table top, I can rotate the helicopter 90 degrees in one minute and the gyro does not see it.
If this rotation was caused by a light breeze, the effect would be the same.
Except by your experiment, it would suggest that the heli will rotate 90 degrees per minute in flight. And it doesn't.

I can get way more into the scientific method, but setting up an experiment as close as possible to actual conditions will yeild a more valid result. In our case, as close as possible to actual conditions is a flight test.

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08-10-2010 08:01 PM  8 years agoPost 32
BarracudaHockey

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Jacksonville FL

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Rain dance! LOL Awesome!

My point is, that rate mode setup gets you "close" to where the thing will spend much of its time, well so does centering the servo, which btw I've had plenty of success with as well.

As I say, they both work.

The funny part about that rate mode setup is about only 1 out of 5 people that insist its the "right" way to setup a gyro even know why. The other 4 are just parroting what they read somewhere.

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

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08-10-2010 08:37 PM  8 years agoPost 33
LonR

rrElite Veteran

Macomb,Mi

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I will always set my tail up in rate mode while hovering around 1900 rpms and the reason for that is its easyer on the tail servo and it will last longer.The tail is pretty much dead nuts centered so its not fighting to keep it centered.
Setting the tail up in HH works but its more wear and tare on the tail servo because it fighting/working harder to keep the tail centered.When setup in rate mode its close to center so the servo isn't working as hard to stay centered which is easyer on the servo.

I guess do what works for ya but its clear as day that Hamo isn't doing something right because hes the only one with drift while everyone else doesn't.

600LE,OS55,OS PowerBoost pipe,Align 610's,Spartan

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08-10-2010 08:39 PM  8 years agoPost 34
BarracudaHockey

rrMaster

Jacksonville FL

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You're one of the 4

Edit, but you're on the right track

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

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08-10-2010 09:20 PM  8 years agoPost 35
Heli_KV

rrKey Veteran

Ottawa, Canada

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Just to put some for debates for rate mode setup. When it is setup dead on in rate in upright mode, try to flip inverted and hover and you'll see that tail drifts. A little bit, but still. Downwash from main rotor influences in upright and it does not in inverted.

PS. I setup in rate mode first for the reason of flipping accasionally switch and to avoid surprises. At least I test in rate mode to see if it is acceptable.

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08-10-2010 09:52 PM  8 years agoPost 36
mustang67ford

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Central Pennsylvania

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Ok, so I have concluded that tail drift is not normal and that it is adjusted by the pushrod and not the gain. This answered my question.

However, I do need to disagree with those who say not to adjust the pushrod using the trim. I had actually talked to futaba on the matter. They noted you can us the trims to adjust the center. If you are in normal mode and use the trims to adjust center and land, power down then power back up in HH mode, the new position of the servo will be recognized by the gyro as center. The servo can be to the full right or the full left and if the heli is powered up in this position in HH mode, then that is what the gyro recognizes as center.

Somebody mentioned about the electrical pules to the servo if not centered, this makes some sence on how the gyro would know it off center,interesting.

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08-10-2010 09:55 PM  8 years agoPost 37
Aaron29

rrProfessor

USA

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You want to mess with trim, go for it.

I just thought I'd share my method, which has served me well.

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08-10-2010 10:06 PM  8 years agoPost 38
BarracudaHockey

rrMaster

Jacksonville FL

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The problem with using transmitter trim vice sub trim is that many transmitters store the trim per flight mode, so if you trim it in normal, and reset the gyro, then flip to idle up, then the trim position will change and the gyro will take that as a stick input and start "drifting" though its actually doing what its told.

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

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08-10-2010 10:10 PM  8 years agoPost 39
Ronald Thomas

rrMaster

Gainesville, Fl, USA

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Mechanical adjustment is always best with a 401. Typically vibration and large temp changes will only cause a drift.........Ron

Team MikadoUSA 480XXTreme, 550SX, 600SX, 700XXTreme, 800XXTreme!!

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08-10-2010 10:11 PM  8 years agoPost 40
Aaron29

rrProfessor

USA

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Last thing...

Without trying to sound like a jerk, I really could care less what Futaba has to say on the matter. My setup works for me and everyone I have done the setup for.

Whether or not someone wants to agree with me, disagree with me, take my advice, or dork with trims isn't going to change the way my heli flies one bit.

Have at it.

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HomeAircraftHelicopterRadio - Futaba FASST › tail drift and gy401
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