T-rex 500 Jr 770 Gyro and 8900 Problems

[n210rm]

Anybody have any setup suggestions for the Jr 770 and 8900, I'm unable to get the gyro to calm down and act lacked in, starting with the suggested settings it wags really Bad, 12 + inches in both directions..
Tried lower gain
Shorter arm
Checked everything twice

Any Help would Be greatly appreciated

Ray

T-rex 600N
T-rex 450
T-rex 600
T-rex 500 new to this one

[huskynox]

Little more info would help? Radio, Gain Setting, Arm Length, etc.

Why are you using a 8900G? 3400G works fine for Jason Chow......?

[n210rm]

we Bought the servo and Gyro Thogher and I thought it would work, I was thinking of trying the 3400.. the arm was at 11.5 than shortened to 8, tried lowering the atv and Gain, the atv from 70 to 150 Gain from 20 to 80. When the Gain is high it wags and when its low it seems to be too soft, won't lock in at all just seems to drift. I can go up an Gain and it starts to wag, Better than at first but not good if I get it to stop any rudder input makes it start again..

Ray

[huskynox]

we Bought the servo and Gyro Thogher and I thought it would work, I was thinking of trying the 3400.. the arm was at 11.5 than shortened to 8, tried lowering the atv and Gain, the atv from 70 to 150 Gain from 20 to 80. When the Gain is high it wags and when its low it seems to be too soft, won't lock in at all just seems to drift. I can go up an Gain and it starts to wag, Better than at first but not good if I get it to stop any rudder input makes it start again..

Ray

Ray,

Your arm should be between 9-10mm long. I'm still not sure what radio your using? If you're on a DX7 or 9303 you should have you end points maxed out at 150%, then set your gain channel to 30% for initial setup. Be sure your end point on the 770 gyro is setup for max-travel while setting up in "Normal Rate Mode" (30%) with NO BINDING of the pitch slider.

Make sure your pitch slider is as close to center as possible with your radio at center stick. I actually like to do this by plugging the servo directly into the receiver so there's absolutely no gyro interaction.

Make sure your frame rate switch on the 770 is set to "high" for the 8900G servo.

Now while in Flight Mode 1, and the gain set at 30% try to hover the Heli. If it spins to the left, shorten your control rod. If it spins to the right, lengthen your control rod. You're trying to get it set up to head-hold in "normal rate mode". Once you've accomplished this. Set your gain to 65% (Head Lock Mode) and see how it flys. You should be between 60% and 65%. 1% makes a big difference with the 770 Gyro and X9303 radio.

Again, this is for a DX7 or 9303.

[n210rm]

Thanks for the help Huskynox,
I'm sorry I should have stated that this is a 9303. I'm wondering if the problem is that I have been using 401's and maybe the 770 3D needs smaller adjustments ?
I wanted to try the 770 3D and maybe should have stuck with the old standby but it seemed like a good idea to try the Jr. new stuff

thanks again Ray

[terrabit]

How's that working out? I have that combo in my Logo 600 3d. I had to take the gain all the way down to 25% to calm the tail down. Can that possibly be right?

[heli-dan]

Terrabit,

I had the same problem with my Trex 500. I found two things that contributed to my tail wag. The location of the gyro and the length of the servo arm. I moved the gyro from the top of the tail bearing block to the base plate and shorten the servo arm from 11mm to 8mm. With my gain set at 53% the tail is very responsive and rock solid while doing 3D maneuvers.

I’ve only had three flights on my 500 (hope for more today), but I put it through ever possible trick I can do and I would have to say I really like the combo.

[nate735]

Terrabit,

I had the same problem with my Trex 500. I found two things that contributed to my tail wag. The location of the gyro and the length of the servo arm. I moved the gyro from the top of the tail bearing block to the base plate and shorten the servo arm from 11mm to 8mm. With my gain set at 53% the tail is very responsive and rock solid while doing 3D maneuvers.

I’ve only had three flights on my 500 (hope for more today), but I put it through ever possible trick I can do and I would have to say I really like the combo.

What tail servo are you running ?

[terrabit]

Hey thanks! I'm working on it.

[heli-dan]

8900g...

[WayneBrown]

you also need to look at the output of your esc, I've had some issues with voltages over 5.6v.
8mm may or may not be right, you need to determine the length out based on the lever moment of the bellcrank.
With the rod disconnected and limit at 100%, put the bellcrank to full left, and input full left on TX, mark the servo arm and repeat for full right. Mount the ball at the mark.
Mount the ball so you have 100% limit, and test fly the machine in rate mode and adjust for no drift. Switch to HH and adjust piroette rate/ gain to suit.
Works every time.

[huskynox]

I'm running the 770 3D with the 3400G. 10mm arm with 58% gain on an X9303. The thing feels great!

I will say I orginally had a 12T pinion which sucked, but when I switched to the 13T everything came together.

I'm running the new Thunder Power 2200mAh 6S Extreme pack.

[biohazrd]

Ray,

Make sure your pitch slider is as close to center as possible with your radio at center stick. I actually like to do this by plugging the servo directly into the receiver so there's absolutely no gyro interaction.



Sorry if you have gotten multiple emails regarding my revision of this post, however I was interrupted several times in between getting my facts and dinner..... When you mean center the pitch slider, do you mean center as in no pitch in the blades or center is as in center the pitch slider on the tail shaft? Some tails are not symmetrical. On my Trex 600N, no tail rotor pitch (neutral) appears to be centering the pitch slider on the tail shaft.

I am confused on this subject as some people have told me to build the heli with the tail pitch control arm "L" (the part that connects to tail servo control rod) to where it is parallel to the tail shaft rod. This leaves it with slight right rudder input and more room to travel for left rudder. [All of this assuming that the length of the tail servo rod keeps it 90 degrees on the tail servo.]

Also I have heard 2 versions of getting it to hold in rate mode. One by using rudder trim, the other camp says rudder trim can and should be done mechanically with the tail servo push rod length. Even the JR 770 manual says it can be done with trim unless trim alone will not pull it straight. I am wondering your opinion on this.

I throw this out for general information as some people seem confused on the gyro gain settings. This gyro does operate with gain settings less than a 401 and is normal. If anyone is confused on the wide range of numbers people are posting on their gain settings, the difference is in what method they are using to control gain. I have found some are referring to gyro sense gain and others to ATV (+100/-100) values when using it tied to a switch on the TX.

Setting of 62% in gyro sense = setting of 24% when using ATV method.
(Sense Setting - 50 * 2) to calculate the equivalent in ATV for Head Holding.

On the Normal Rate side, that same ATV value of 24 = 38% on the gyro sense scale.
( 100 - Sense Setting for HH Mode )

[WiscHeli]

I have a 500Cf with G770-3D /DS3400g arm 8.6mm
JR 9303 PCM Syn
PCM 790Rx Syn
BEC 6v

Settings
ATV +-150
Gain rate 38%
Gain HH 62%
EXPO +50%
Dual Rate 60%

what am i doing wrong
:arggg:

[huskynox]

I have a 500Cf with G770-3D /DS3400g arm 8.6mm
JR 9303 PCM Syn
PCM 790Rx Syn
BEC 6v

Settings
ATV +-150
Gain rate 38%
Gain HH 62%
EXPO +50%
Dual Rate 60%

what am i doing wrong
:arggg:

What's the problem? Just initially looking at your specs, it looks like your arm is too short.

[WiscHeli]

Thanks
I moved the arm out to 10mm its holding better now :thumbup:

Danm this g770-3D is not plug and play ,, need to adjust so much in rate before going to HH .. i am getting it set closer now still a little wag

[huskynox]

Thanks
I moved the arm out to 10mm its holding better now :thumbup:

Danm this g770-3D is not plug and play ,, need to adjust so much in rate before going to HH .. i am getting it set closer now still a little wag

Try 57-58% gain (assuming you're using the 13T pinion?). 1% change makes a significant difference (believe it or not).

Yeah, the 770 is a bit strange as far as having to get the mechanical setup so close, but I haven't had a problem. Just get it close in Rate Mode (within 1 turn on the ball link) and you're good. A slight drift in Rate Mode is OK, but a lot of drift is bad.... when you switch to HH mode (you WILL get drift!)

[deanholmes]

Sorry if this is a bit basic and to hijack your thread but its related.

I have a 9303 radio with 770 gyro and 8900 servo on 600n.

I have a 401 gyro in my raptor 30. Normally I would put the sync lead of the 401 in channel 5 (gear) of the radio. The 770 manual (leaflet) says Aux 2 which is correct?.

With it in the gear channel I can turn on & off Gyro's HH mode with the gear switch on the 9303. When this is off is this what you call rate mode?

In the Gyro sens screen there is too settings, position 0 & 1. Which one is HH and Rate mode? and is it my gear switch that is changing the position.

Thanks
Dean

[Socal500]

Not familiar with that radio but it depends on what you have set on your INPUT SELECT screen. Im assuming that your radio will have more options than the DX7 but I would think some of the menus are alike.

Go to the Input Select Screen and you should whats below. Leave this as is if you want to use TRV ADJ instead of the GYRO SENS option.

AUX2______GEAR
__AUX2______GEAR

Change it to whats below if you want to plug the sens wire into the GEAR channel
AUX2______GEAR
__AUX2______ GYRO

Change it to whats below if you want to plug the sens wire into the AUX2 channel
AUX2______GEAR
__GYRO______ GEAR

Access the Gyro Sens and set it to AUTO and you get something like this.
RATE:_______NORM:0
0:72%_______STNT:1
1:68%_______HOLD:0

On the left you set two gains represented by 0 and 1. On the right you select which of those gains will be used by each flight mode. STNT 2 is not listed but is the same as STNT 1.
So from the settings above when the flight mode switch is in the NORM position, my gain is 72% but when I switch to FLIGHT MODE 1 or 2 it automatically changes to 68%. Hold would also be 68% since its assigned to the 0 value as well.

Neither of the above is RATE mode. In order to get into RATE mode you would set one of the values to 40 or below. I would set 0: to about 30 to start with and then assign 0: to NORM . After setup you can go back and change this number back to something above 60 to put it back to HH mode.

This is a basic representation of the settings using gyro sens.
http://www.socalsurfs.com/gyromenu.jpg


This is basic rep of using TRV ADJ.
http://www.socalsurfs.com/atvmenu.jpg

[biohazrd]

You can use the gear switch and channel 5 on your receiver to control gain. If I recall 0 is HH and 1 is rate mode. If you assigned rudder D/R to the gear switch flip it and move the rudder stick. If the servo holds in one position and does not return it is in HH mode. If it returns to center it is in rate mode. Using the rudder D/R switch is using the ATV method to set gain.

If you are going to use a governor with the 9303, it uses the gear channel and you setup the gyro sense on AUX2. In that method you assign the sensitivity by flight mode. (I found no way to AUX2 to the rudder D/R switch for just on or off) After installing my governor and playing with it in this fashion last night, I found anything under 49 is rate mode anything above 51 is HH mode for each flight mode.

Hope that helps.

[deanholmes]

Thanks that helps, yes I have the align governor which I had plugged into Aux 2, but I can swap these.

I agree under the 9303 you are limited in what you can assign switches too.

dean

[Socal500]

After reading all the posts about setting up mechanically I decided to try it. Adjust linkage so the tail held in rate mode with my gain setting about 28 (Gyro Sens Value) and just on the edge of wag. It actually held solid with no drift so Im thinking its all good. Well I set it down, unplug the battery, set my TX back to HH. Plug it all back in, lift and then adjust my gain to 67 (GSV), which was just under a wag. I end up with a drift.

So I reverted back to the 770 manual instructions, which do not instruct you to setup the tail to hold mechanically and I get a solid hold no drift. The only reference I find to setting up mechanically is after the HH instructions... IF you are going to use normal mode and even then they instruct to use trim.

Go figure... who would have ever thought that following the directions would work :)

[macsrgreat]

Morning, I am running the 7703D works great, here is how i set up.

BELT TIGHT but NOT to Tight (This is very important to loose and the tail will wag like crazy just like a 600 the belt should be tighter than 450!)

DX7 using the gear channel as gyro
All the normal rules almost just like a 401:
3400G servo
I set Heading Hold to 30 and Normal mode to 30, (this is where things are a little dif than a 401)

Travel adjust to 100% you don’t have to do 150

Then on the ground IN NORMAL MODE with the horn at 90 center the pitch slider and check for binding with the pot on the gyro, adjust this on the ground to be as much deflection as possible without binding, check the direction to make sure it doesn't need reversed or left to normal the switch for refresh rate to high for all JR digital servos when that is all good take off and hover in NORMAL MODE see which way the heli drifts if it goes RIGHT shorten the rod if LEFT lengthen the rod once holds in normal mode switch to heading hold and adjust gain mine is at 20 works great! you can use the Dual Rates with this gyro to how hard it stops to keep from stripping gears. Adjust the expo on the rudder channel to your comfort. Hope some of this helps.

Rus:)

[robmoney]

Rus,

What happened with the Solid-G?

[macsrgreat]

well my esc smoked itself and sent a charge through the system and the g-view and the amp were harmed. the amp would work but not update the with the g-view, i tried to other g-views so...any who i am using this gyro becasue i had never set up a 770 and thought i would give it a try, i will put the solid g back on at some point. I cant say enough nice things about the guys that work for Curtis, top notch. At the time i sent it a few days earlier Curtis was flying the 500, Brian said that they had it figured out on the numbers for the tail, but that the tail was not as strong as they hoped. Carbon blades and little bigger will help all of that i am sure but anywho long story short it will be back shortly and i hope:YeaBaby: with the numbers to adjust to have it be rock solid. I fly the solid G in my 600 and it rocks!


Giddy UP, Rus:lol: