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HelicopterRadio - Servo - Gyro - Gov - Batt › JR 7703D tail bounce problem on 450
11-27-2007 03:27 PM  10 years agoPost 1
Jay1

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Colorado Springs

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I just installed a JR 7703D on my 450 V2 to replace a faulty 401 that gave out. After everything is set up, the thing holds like a vise but when I give L/R rudder quick inputs the tail overshoots and bounces back. Here is what I have set:

3180 HS
ATV L 150%
ATV R 150%
Exp 57%
D/R 80%
JR 3400G tail servo
Gain (Spectrum DX7) 54% where tail does not wag

I am happy that it holds great but I am afraid to do any piros as the tail does a quick overshoot bounce and locks the tail but not where I stopped it at. My 401 use to stop on a dime. What can I do to stop the tail from the whole bounce affect?
Thanks

Jay
Sooner or later, Gravity will win!

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11-27-2007 04:03 PM  10 years agoPost 2
baddynergy

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sierra madre, ca- usa

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lower your expo

**Unattended children will be givin a shot of espresso and a puppy**

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11-27-2007 04:10 PM  10 years agoPost 3
Jay1

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Colorado Springs

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lower your expo
I will do that. I was under the imppression that the expo helped with that issue in slowing it down but I guess I was wrong.

I was just following the directions on the instructions. My 401 was set at LIN. Can I ask why this gyro has this issue while the GY one doesent? Just trying to understand its characteristics.

Jay
Sooner or later, Gravity will win!

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11-27-2007 04:45 PM  10 years agoPost 4
baddynergy

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sierra madre, ca- usa

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Not sure on that gyro, but any expo on any gyro will slow down your response, hence the bounce. And if I read your post correctly you are at 57% expo. Bring it down to 20 to see if that stiffens up your input.

**Unattended children will be givin a shot of espresso and a puppy**

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11-27-2007 05:00 PM  10 years agoPost 5
Jay1

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Colorado Springs

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Yes you are correct, I have the expo at 57% right now.

I will try that when I get home from work.

I spoke to Horizon and the techs there said that this is not the characteristics of that gyro. They mentioned that it should lock and not have any bounce like its trying to re-center itself. They adviced me to send back in for warranty. I was really tring to avoid this as I have my 401 sent back for warranty and now this.

Jay
Sooner or later, Gravity will win!

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11-27-2007 05:01 PM  10 years agoPost 6
DS 8717

rrProfessor

Here wishing i was somewhere else

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Are you just letting the stick go so it can return to center,i have seen people do this.It will cause it to bounce with a good gyro like the 770. Also dont use trims or sub trim to center the TR,do it by adjusting the lenght of the rod so the tail holds without drifting to either side.

YOU ONLY LIVE ONCE..IF YOU LIVE IT RIGHT THATS ALL YOU NEED

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11-27-2007 07:13 PM  10 years agoPost 7
Jay1

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Colorado Springs

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Are you just letting the stick go so it can return to center,i have seen people do this.It will cause it to bounce with a good gyro like the 770.
Hummmm, you are right about that. I do do that when testing. I never had an issue with the 401 doing that with me quickly pushing to L/R and letting the stick go. It use to stop like I hit a brick wall.

I set up everything mechanically so it is dead center. All my electronical trims are at Zero. The head is lock solid with no drift. I was hoping to get this 770 to lock like my 401 did is all.

I test my 611 on my 600N the same way and it does not act like the 770 with a bounce back affect.

What do you suggest I can do to calm that bounce affect?

Jay
Sooner or later, Gravity will win!

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11-28-2007 02:05 AM  10 years agoPost 8
AeroSports

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NJ

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assuming that the linkage are setup correctly and you are using the gyro menu of the dx7, 57% translates into 14% of gain in heading hold. that is to low. what you described shows just that.

start with 65% and adjust accordingly.

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11-28-2007 02:56 AM  10 years agoPost 9
artimus

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Buckley WA

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Also make sure that the Expo is going the right way ..... Neg expo vs pos expo...I had mine backwards and it would get bouncy at zero stick

Fly Hard......Team Viagra

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11-28-2007 03:57 PM  10 years agoPost 10
Jay1

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Colorado Springs

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gyro menu of the dx7, 57% translates into 14% of gain in heading hold. that is to low. what you described shows just that.

start with 65% and adjust accordingly.
I spoke to Eco8gator about this issue and he mentioned that I needed to increase the gain by reducing the linkage size. I have reduced it down to about 7mm from ball link to center of servo horn. I was able to increase to 60% but I still get a wag/bounce when moving L/R without letting the stick go and it slowly creeps back the opposite direction. Anything above that I get the "high gain wagg".

Horizon suggested that I send it in as they said that should not be doing that but I wanted to eliminate any part on my side that I could fix first.

I have worked with the expo in both +/- and no luck.

Jay
Sooner or later, Gravity will win!

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11-29-2007 01:00 AM  10 years agoPost 11
fiveoboy01

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Waunakee, WI - USA

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assuming that the linkage are setup correctly and you are using the gyro menu of the dx7, 57% translates into 14% of gain in heading hold. that is to low. what you described shows just that.
Um, rudder expo doesn't have anything to do with gyro gain

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12-03-2007 04:10 PM  10 years agoPost 12
Jay1

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Colorado Springs

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Thanks guys for all the input on trying to resolve this issue.
I was almost there but I could not get the gain high enough to stop bounce even after moving the ling 7mm to the servo arm. That was the closest I could get it without binding. The 770 might not be the 450's preffered gyro. People in the 600 class seem to have better luck.

I just decided I am going to go with the Spartan DS760 instead.

Jay
Sooner or later, Gravity will win!

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12-03-2007 04:16 PM  10 years agoPost 13
artimus

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Buckley WA

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Get a 401 and your problems will go away......

Fly Hard......Team Viagra

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12-03-2007 04:34 PM  10 years agoPost 14
DS 8717

rrProfessor

Here wishing i was somewhere else

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using the 770 on a 450 is like trying to fill a glass with a fire hose,use some thing less effeciant like a 401.

YOU ONLY LIVE ONCE..IF YOU LIVE IT RIGHT THATS ALL YOU NEED

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12-03-2007 05:38 PM  10 years agoPost 15
Jay1

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Colorado Springs

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using the 770 on a 450 is like trying to fill a glass with a fire hose,use some thing less effeciant like a 401.
Good one! Ah, I had to give it a try. Lesson learned.

Jay
Sooner or later, Gravity will win!

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12-09-2007 10:37 PM  10 years agoPost 16
KevinB

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Saskatoon, Saskatchewan, Canada

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Hi Jay.

I had the exact same issue. Trex 450V2, 770, and a 3400G.

It all started when I wanted to get better tail hold in backwards flight. I actually tried putting a 601 gyro/servo combo on the Trex to see if the heli was capable or not before I spent the money. The 601 held the tail like a vise no matter which way it was flying or how bad a screwed up manoeuvers. So...after hearing everyone saying how the 770 was finally the first JR gyro to equal a 601, I bought one.
I started with the recommended settings including the servo arm length, and as soon as I broke ground the wag nearly tore the tail off. I decreased the gain down to 65% before the wag went away...but at this setting it had the annoying bounce you spoke of and didn't hold near as good as the 601....perhaps not even the 401.

I'm going to try the 770 with an 8700G on my evo50 next spring to see if it works any better there. For now, it just joins the other JR heading hold gyros on my workbench shelf.

Could you PM me with your results with the Spartan DS760 once you get it ? I'd be interested what you thought of it.

Thanks,

KevinB

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12-09-2007 11:05 PM  10 years agoPost 17
george0079

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USA

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using the 770 on a 450 is like trying to fill a glass with a fire hose,
Or maybe.. Trying to swat a fly with a sledge hammer.

Hell... I can fix that.
Uh oh..
Nope.
It's ***ked!!!
RE-KIT!!!!!

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HelicopterRadio - Servo - Gyro - Gov - Batt › JR 7703D tail bounce problem on 450
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