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HomeAircraftHelicopterAlignT-REX 700N › Trex 700LE Maiden - 2 Issues with GY520 Gyro - UPDATE
04-08-2010 06:25 AM  8 years agoPost 1
Rockohaulic

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Canyon Country, CA, USA, 3rd Rock from the Sun

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So the maiden went really well, but there is room for improvement with the tail/gyro.

1. The tail just wasn't solid. It was not a high gain wag, and it was not a low gain drift. And this engine is from my old 700N, so I was not breaking in a new engine. But the tail just was not rock solid.

What tips and tricks have you guys with GY520 gyros and Trex 700s done to get a solid tail? What gain are you using? Did you use the stock foam mounting tape? What thickness did you use? Did you instead try other foam tape like the 3M stuff?

2. There was noticable bounce back in piros. I set parameters up with the basic defaults. To attempt to fix the bounceback issue, I set Parameter 5: Gyro Response Rate from Standard to Slow Response. This did not help.

Is there anything else I can do with the standard settings??? Right now I do not have the cable to allow me to set it up with a laptop.

If and when I do get a cable to allow programming from a computer (God I miss using a simple G-View!), what parameters should I adjust to lock this thing in???

Thx guys.

Saturday morning I flew my helicopter in my pajamas
How it got in my pajamas I'll never know

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04-08-2010 07:12 AM  8 years agoPost 2
outhouse

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auburn ca

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Im using the thick foam tape and the metal plate and another thick piece of foam on mine and its rock solid no pc cord either.

I used all standard settings but i do run it on a 9256 servo

im using 45 on gear channel DX7

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04-08-2010 12:45 PM  8 years agoPost 3
Pulento

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CHILE

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Set your tail link to have no drift in rate mode then go back to HH mode.

I'm using thin foam, then the metal plate and finally gel tape as Zeal or Blue Align.

Check Bobby Watts site for tips.

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04-08-2010 04:44 PM  8 years agoPost 4
Rockohaulic

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Canyon Country, CA, USA, 3rd Rock from the Sun

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Check Bobby Watts site for tips.
Sounds interesting.

What is his website address?

Saturday morning I flew my helicopter in my pajamas
How it got in my pajamas I'll never know

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04-08-2010 04:45 PM  8 years agoPost 5
Rockohaulic

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Canyon Country, CA, USA, 3rd Rock from the Sun

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BTW - I'm using a BLS251 tail servo.

Saturday morning I flew my helicopter in my pajamas
How it got in my pajamas I'll never know

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04-08-2010 08:31 PM  8 years agoPost 6
ckd

rrApprentice

Saugus CA

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I loved the 520 before I went FBL. I used the stock thin tape plate and thin again. I was using the 8900G servo. Its been a while but I think I was around 25-27 on gain. I did set up in rate mode first like Bobby talks about. Fast inverted backwards with it was never a problem. The bounce back was talked about a while ago and I forget what setting worked best. You can also pick up the usb link to play with all settings.

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04-08-2010 09:20 PM  8 years agoPost 7
BLUETHUNDER

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Glass City

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Use the FAI setting to help with bounce back.

http://www.bobbywatts.com/site

http://www.youtube.com/watch?v=_qri...feature=related

Watch at YouTube

Gyros FAQ
Do you have any tips for mounting the GY520?
Due to the high performance of the gyro, it is sensitive to any harmonics and/or vibrations. As such, the mounting methodology is very critical. The user needs to experiment with the isolation tape and the location of the gyro itself.

To determine if a problem exists, the modeler should bring the helicopter into a hover and observe the tail for any unintentional movement. If any exists, the modeler should change the tape configuration. To start with, the modeler should use a single 2mm piece of tape. Next, add the second piece of 2mm tape with the metal plate between them for added stability.

It is also important to observe the 'drift' of the gyro when in the heading hold mode. If the helicopter drifts, rotate the gyro by 90-degrees. This allows the gyro to 'see' the helicopter on a different axis.

And last if problems are noted and the above suggestions do not resolve the issue, the modeler should change the location of the gyro itself within the helicopter.

Gyros FAQ
Do I trim my GY520 in the gyro's heading hold setting?
When using the GY520, it is imperative for the modeler to trim the helicopter in the Normal mode and not using the gyro's heading hold settings. All Futaba gyros have some amount of AVCS gain pre-programmed from the factory. If the model is trimmed while compensating for this, the model would exhibit poor tendencies in certain flight conditions.

Gyros FAQ
My tail bounces a lot during hard tail moves, have I set up my GY520 incorrectly?
Bouncing will take place when the gyro operation speed and the heli's operational speed do not match.

If you are having "bouncing" during hard tail stops, it may be because the response of the gyro is faster than the heli tail movement caused by too fast of a response setting.

Different brands of helicopters use different gear ratios. In order to get the optimum performance between the GY520 and all brands of helicopter, you can either adjust the rudder delay in your transmitter, or change the servo response setting to a slower speed to help resolve any issues. (Example: From Fast>Reference>Slow)

The CIU-2 parameter setting option will offer a more detailed setting with the AVCS response setting menu.

In other circumstances, if your heli has too hard of a stop, and there is no bounce. You can use the methods above also. The pirouette consistency menu on the CIU-2 programming can be set to a value lower than 7 also, for more moderate operation of the rudder control. You may also adjust the AVCS Right Out and Left Out if your transmitter does not have rudder delay.

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04-08-2010 09:23 PM  8 years agoPost 8
Rockohaulic

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Canyon Country, CA, USA, 3rd Rock from the Sun

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Use the FAI setting to help with bounce back.
I forgot to mention - it is on the FAI setting.....

Saturday morning I flew my helicopter in my pajamas
How it got in my pajamas I'll never know

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04-09-2010 02:34 AM  8 years agoPost 9
Pulento

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CHILE

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What is the length of your tail servo arm ?

Usually increasing it can help with bouncing. I had bouncing in my Vibe 50 so I double checked with the CIU-2 that my limits where near 100 which mean that you are maximizing servo resolution and then played with stop gain (don't remember exact name).

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04-09-2010 03:30 AM  8 years agoPost 10
jschenck

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La Vista, NE.

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520 on my 700 is 'rock solid' with a Hitec 6965 servo. Ball is 14.5mm out on the servo. I use 4 push rod guides, I think that helps. 520 is mounted with two pads and the metal plate in the middle. My 520 is turned 90º and I supported the cable without making it tight. This is the best, most solid tail I have, though my Predator is a close 2nd.

9303 gain in idle-2 is 67 in the gyro menu.

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04-09-2010 03:41 AM  8 years agoPost 11
jschenck

rrProfessor

La Vista, NE.

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04-09-2010 04:14 AM  8 years agoPost 12
TMoore

rrMaster

Cookeville, TN

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I run the 3D mode, fast response and run the AVCS response(right/out and left/out) to 10. This will reduce the bounce on stops.

TM

Delayed Response Operator Not Engaged
AMA SECTION 336 = Good
Drones = EVIL

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04-09-2010 05:00 AM  8 years agoPost 13
outhouse

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auburn ca

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mine is mounted just like the one above

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04-10-2010 09:58 PM  8 years agoPost 14
Rockohaulic

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Canyon Country, CA, USA, 3rd Rock from the Sun

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Update:

Woo Hoooooooooooooo! What a difference a weekend makes!

Yes I leaned the engine a bit, so that might have helped smooth out things a bit. But I made some changes to the GY520 gyro that really made a big difference.

First, I checked the length of the servo horn, and it was at the recommended 14.5mm. So I didn't touch it. So I noticed that the tail blades had very little offset, so I set up rate mode in Idle 1, and brought it up into a hover and set the tail in rate mode. Even though I adjusted more offset on the bench (about 2 turns on the tail rod ball link), it still drifted quickly to the left. It took a couple more turns to stop the drift.

This made a big difference.

Second, last night I decided to change out the way the gyro is mounted. Now bare with me here...... I had 2mm foam, plate, and 2mm foam. In theory, you are trying to suspend/damp the gyro like a car is suspended by the suspension. The gyro is the sprung mass. The higher the sprung mass - the better. Also, I believe that having a thick piece of foam between the plate and the gyro is defeating the purpose. My theory is that the 2 should act as a mass together. So I was going to place some thin tape between the plate and gyro.

So as I was cleaning the old foam off, I noticed how thin and light the plate was. The plate for the Spartan 760 is much thicker and heavier. So I decided not to use the thin plate, and to buy a Spartan plate. With this plan in mind, I decided to just mount the Gyro on 3mm tape temporarily for this weekend, and I would redo the whole thing once the thick plate arrived.

But to my surprise the Heli was unbelievably steady today!!!

I do this one maneuver where I put her up high and put her into a tail slide, then I pull out inverted tail first and hold elevater for 180 deg until she is now tail to the sky. Well today that tail was perfectly straight in the air - I did not have to correct at all with rudder - the gyro held that thing solid! I did it several times, and each time that tail was at 12:00. Beautiful!

She was also solid in a hover. In the end, the guys all said don't touch a thing! They convinced me not to touch it because I might break it. Even though I desparately want to prove my theory, I think they are right - that tail was solid today!

Anyway, I am really happy with this Trex 700LE and the 520.

I even did some awesome tic tocs on my last flight - I normally suck at tic tocs. One of my buddies was wondering where the hell did I pull that out of!!! I can do them great on the sim, but until today I have never had my helicopter behave so closely to the sim. It was great!

Saturday morning I flew my helicopter in my pajamas
How it got in my pajamas I'll never know

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04-11-2010 04:49 AM  8 years agoPost 15
jschenck

rrProfessor

La Vista, NE.

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So 3mm foam and nothing else? - proof is in the flying! My tic-toc's suck too but the 700 makes 'em look good. Need a lot less collective than you think you do.

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04-12-2010 03:02 AM  8 years agoPost 16
marc8090

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Long Island, N.Y.

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I'm using Zeal tape with no metal plate and it's been working great.

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04-12-2010 03:43 AM  8 years agoPost 17
ckd

rrApprentice

Saugus CA

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dont forget to check travel limits after setting up in rate mode.

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04-12-2010 09:26 PM  8 years agoPost 18
Randog

rrApprentice

Santa Clarita,California,U SA

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Man alive,I am going to rip off my Spartan and Install a GY 520. There I was talking to a friend when I looked up in the sky and saw a 700 doing some Tic Tocks.

Much to my surprise it was Rock at the Wheel. They were very nice and I was surprised because he never does them. Keep it up and before long you will be doing them right on the deck!

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