RunRyder RC
WATCH
 1 page 1425 views POST REPLY
HomeRC & PowerAircraftHelicopterRadio - Servo - Gyro - Gov - Batt › tail bounce - any ideas to fix
10-11-2011 10:38 AM  7 years agoPost 1
imf

rrNovice

UK

My Posts: All  Forum  Topic

I have a Mini Titan with a GY520. Does not matter where I set the gain percentage 20% or 70% the tail still bounces when I stop a pirouette and that not a fast pirouette.

Servo ball is set to 7.5mm centre, gyro mounted on one piece of 2mm foam pad (as recommended in instructions, rudder endpoint set to 100%, Gyro set to F3c mode and fast response (but was the same when set to standard response). Absolutely no tail mechanism binding.

Any ideas?

PM  EMAIL  Attn:RR  Quote
10-11-2011 02:55 PM  7 years agoPost 2
gouki

rrVeteran

philippines

My Posts: All  Forum  Topic

are you using plastic tailblades? did you check for slop on your tail?

PM  EMAIL  GALLERY  Attn:RR  Quote
10-11-2011 05:59 PM  7 years agoPost 3
imf

rrNovice

UK

My Posts: All  Forum  Topic

Radix carbon tail blades and the smallest amount of play in tail mechanism. Got more play in t500 tail and no bounce.

I've been trying different things and got it to a minimum but still there on quite fast piros only. I set 520 to 3d mode and the responce to slow. Put up the end points to 130% with 20% expo on rudder and it feels really nice, better than it has ever been with the GY401 - very progressive but powerful and holds like a rock.

Will continue to fiddle and let you know if I illiminate bounce. I'm wondering if it is some interaction with the belt drive!!!

Thanks for replying.

IMF

PM  EMAIL  Attn:RR  Quote
10-11-2011 06:36 PM  7 years agoPost 4
imf

rrNovice

UK

My Posts: All  Forum  Topic

gouki,

I forgot to say, I have a softening expo set ('-' with Futaba) on the rudder a headspeed of 3400rpm in idle up and a max gain of 43% in AVCS and 70% in rate mode.

IMF

PM  EMAIL  Attn:RR  Quote
10-13-2011 03:14 AM  7 years agoPost 5
Dr.Ben

rrMaster

Richmond, VA, USA

My Posts: All  Forum  Topic

Do you have access or own a CIU-2 to access the background 520 tuning parameters?

Ben Minor

Peak Aircraft/Team Minicopter Team Futaba Team Kontronik USA

PM  EMAIL  GALLERY  Attn:RR  Quote
10-13-2011 03:50 AM  7 years agoPost 6
helixangle

rrKey Veteran

Mamaroneck, NY - USA

My Posts: All  Forum  Topic

are you TBG centered...

Tail blade grip center means having 3 to 5 degrees of right rudder at neutral stick.

stop bounce can happen if you set the gyro up with neutral = 0 pitch on the tail.

re-set up the tail so when your rudder stick is neutral you have 3 degrees right rudder at the tail blades

Be sure the juice is worth the sqweeze
Remember life is hard...even harder for stupid people

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
10-14-2011 08:35 PM  7 years agoPost 7
jschenck

rrProfessor

La Vista, NE.

My Posts: All  Forum  Topic

Replace the wire pushrod with a carbon fiber pushrod. Been my experience that the wire pushrod on the 325mm size heli's flex a lot. Replace with a CF rod that doesn't flex and a lot of tail problems go away. I don't like doing that on larger heli's but I generally don't run into the flexing tail control on larger heli's. You could also try adding another pushrod support if you want to keep the stock wire pushrod.

PM  EMAIL  GALLERY  Attn:RR  Quote
10-15-2011 03:50 AM  7 years agoPost 8
rexxigpilot

rrProfessor

Florida

My Posts: All  Forum  Topic

Get or borrow the CUI2 and set the stop delay to a higher value.

PM  EMAIL  GALLERY  Attn:RR  Quote
10-19-2011 11:35 PM  7 years agoPost 9
imf

rrNovice

UK

My Posts: All  Forum  Topic

Thanks for your help everyone.

I'll have to look into using the'CIU-2'/'CUI2'.

-----------

Helixangle,

My tail blades have offset when the servo is in 'N' although the instructions do say set the tail blade pitch to '0' degrees when the servo is in 'N'.

---------

jschenck,

That's the only tail problem I have. I'll give the carbon rod a try if everything else fails but I really don't think that is the cause. I don't have the problem on my larger heli's either.

PM  EMAIL  Attn:RR  Quote
10-20-2011 02:18 AM  7 years agoPost 10
jschenck

rrProfessor

La Vista, NE.

My Posts: All  Forum  Topic

I've just had too many issues with the wire pushrod on 250/450 size heli's. They rod work fine on bigger stuff for me, presumably because the rod is thicker and dosn't "S" up under load. I've helped others with this and did good for their small heli. The way I make this is to get some hollow CF stock at the hobby shop that has about the same inner diameter as the stock pushrod. Then clip off the last inch and a half or so of the original rod. JB weld it in place, rouging up the metal a bit. Make it look nice with a small piece of shrink wrap. Important to get it about the same length.

PM  EMAIL  GALLERY  Attn:RR  Quote
10-20-2011 08:10 AM  7 years agoPost 11
imf

rrNovice

UK

My Posts: All  Forum  Topic

If you flex the rod as far as it will go the tail pitch does not visually alter, I have more play in my 500 tail pitch slider and that is fine. I'm going to adjust the servo stop delay using the Futaba CIU2 interface first then if that does not work I'll stiffen the wire. I was thinking of running the wire inside a length of carbon tube, what do you reckon?

PM  EMAIL  Attn:RR  Quote
10-20-2011 02:20 PM  7 years agoPost 12
jschenck

rrProfessor

La Vista, NE.

My Posts: All  Forum  Topic

I've seen that and it works but I'd glue it in place so it won't rattle around. Cut out the middle and it reduces the weight which is good for the ball links.

PM  EMAIL  GALLERY  Attn:RR  Quote
10-20-2011 10:49 PM  7 years agoPost 13
imf

rrNovice

UK

My Posts: All  Forum  Topic

I was thinking of fixing the carbon tube to brakets so it acts like a guide for the wire but not actually putting any weight onto the ball links.

Have not got hold of a CUI-2 yet but have increased the ball centre on the tail servo from 7.5mm to 13 and it has helped a lot but not totally cured it.

PM  EMAIL  Attn:RR  Quote
10-21-2011 12:21 AM  7 years agoPost 14
jschenck

rrProfessor

La Vista, NE.

My Posts: All  Forum  Topic

hmm, that's interesting. Increasing the ball link length on the servo usually makes it worse. Which servo are you using on the tail? Did you use a different servo horn that perhaps is flexing less? I like to use solid wheel servo horns since they have almost zero flex. 13mm is a lot for a 325mm size heli tail servo ball link location.

PM  EMAIL  GALLERY  Attn:RR  Quote
10-21-2011 12:02 PM  7 years agoPost 15
imf

rrNovice

UK

My Posts: All  Forum  Topic

I know 13mm is longer than I would normally make it but I posted my question on RR Thunder Tiger forum and got this response from 'gwright'
"Change the servo arm to a much longer arm,..I'd start with 12~13mm, then adjust the gain until there is no wag. You're looking to get it down to around 30 to 40%. If it's still above 50 or so, lengthen the arm again. Once you get it with no wag and around 40% or maybe a little below (while in AVCS), then go to rate mode and adjust the linkage mechanically to trim it very close to no movement, then switch back to AVCS mode. At this point you should go back into the gyro setup and adjust the endpoints again for no binding. Adjust ATV or AFR in your transmitter to get the desired maximum spin rate. (I prefer AFR as it leaves the trim sensitivity alone).Now, if there is any rebound on stops you can increase the stop delay a point or two at a time to eliminate it. I'm not sure which transmitter you use, but with the 14MZ I actually prefer to set the stop delay in the transmitter,..it's on the AFR screen as "servo-out delay". It's irrelevant if you do it in the gyro or the transmitter, I simply prefer the transmitter as it's quicker to make adjustments since you don't have to stop the blades and go into the gyro setup.
The issue is the speed of reaction which is increased by lengthening the servo arm. It basically speeds up the entire system so it doesn't get behind on the corrections and allow the rebound. One key rule of thumb with the 520 is to get the gain down below 50 , preferably in the 30's, which indicates the arm is long enough.
I just went through this on the X50-E. I've been unhappy with the tail setup but was concentrating on power system, gearing, pitch and left it alone till now. I think the arm I ended up with is around 16mm or so and it took less than a single flight to do all of the above stated setup to get the tail absolutely rock solid.

This is the link to the forum https://rc.runryder.com/t667117p1/

I used a different horn but zero flex although there is a tiny bit of flex in the standard plastic servo mounting brackets. Like the flex in the pitch change rod, there is no visible change in pitch when you flex the brackets.

PM  EMAIL  Attn:RR  Quote
WATCH
 1 page 1425 views POST REPLY
HomeRC & PowerAircraftHelicopterRadio - Servo - Gyro - Gov - Batt › tail bounce - any ideas to fix
 Print TOPIC  Make Suggestion 

 3  Topic Subscribe

Wednesday, November 14 - 3:15 pm - Copyright © 2000-2018 RunRyder   EMAILEnable Cookies

The RC discussion world needs to consolidate. RR is now one choice for that. Its software is cutting edge. It hosts on-topic advertising. Help RR increase traffic buy making suggestions, posting in RR's new areas (sites) and by spreading the word.

The RunRyder Difference

• Category system to allow Rep/Vendor postings.
• Classifieds with sold (hidden) category.
• Classifieds with separate view new.
• Answer PMs offsite via email reply.
• Member gallery photos with advanced scripting.
• Gallery photo viewer integrated into postings.
• Highly refined search with advanced back end.
• Hosts its own high end fast response servers.
• Hosts thousands of HD event coverage videos.
• Rewrote entire code base with latest technology.
• No off-topic (annoying) click bait advertising.
Login Here
 New Subscriptions 
 Buddies Online