Notices
T-Rex heli For all you T-Rex lovers out there, this where you can post!

trex wobbles

Old 01-14-2008, 09:18 AM
  #1  
Member
Thread Starter
 
Join Date: May 2007
Location: jacksonville, FL
Posts: 92
Likes: 0
Received 0 Likes on 0 Posts
Default trex wobbles

hay guys i have a 450xl that wobbles front to back then back again any ideas about what is going on im thingking my gyro is toast
Old 01-14-2008, 10:22 AM
  #2  
Senior Member
 
MiniCwik's Avatar
 
Join Date: Jan 2007
Location: New Baltimore, MI
Posts: 1,035
Likes: 0
Received 0 Likes on 0 Posts
Default RE: trex wobbles

I have a 450XL that I built for my bro, is yours a true wobble or is it just very touchy when flying?

The 450XL CCPM setup is not that good, it allows for too much slop in the cyclic controls and even getting a good CoG is difficult.

What I did was mount the elevator servo directly to the frame behind the swashplate, after cutting a hole in the frame so it would fit through, much like the T-Rex 450SA/SE. Then I picked up two mini titan servo mounts (come two to a pack) and removed the stock servo mounts from the XL frame, all links included and mounted the mini titan servo mounts to the frame below the swash, directly lined up with the swashplate for aileron and pitch. Once I got this all done, man the 450XL is a breeze to fly ... it is super smooth, stable, and just a vast improvement over the stock setup.

Here is a link to the thread that gave me this idea - http://www.daddyhobby.com/forum/show...<br%20/>

If your gyro were toast your wobble would be more of a insane pirouetting effect. Wobbling side to side is a sign that the gyro gain is set too high. Too low and your tail will drift in one direction, requiring constant correction.
Did you setup your gyro completely? In rate mode, etc?
What model gyro do you have?
What tail servo do you have?
Old 01-14-2008, 11:50 AM
  #3  
Member
Thread Starter
 
Join Date: May 2007
Location: jacksonville, FL
Posts: 92
Likes: 0
Received 0 Likes on 0 Posts
Default RE: trex wobbles

its a true wobbler not tuchy in the least its like the main shaft is bent causing the swash to wobble there for causing the heli to wobble but if that was the case it would wobble in all directions not just for and aft plus after my last crash i checked everything and nothing that i can see is bent or broken and trust me i checked and re checked
Old 01-14-2008, 12:02 PM
  #4  
Senior Member
 
MiniCwik's Avatar
 
Join Date: Jan 2007
Location: New Baltimore, MI
Posts: 1,035
Likes: 0
Received 0 Likes on 0 Posts
Default RE: trex wobbles

How is you CoG?

Did you check the main and spindle shaft's for true-ness? Rolling them on a glass plane would be best or other truly flat surface.

How is your blade tracking?
Old 01-14-2008, 01:38 PM
  #5  
Senior Member
 
Join Date: May 2007
Location: San Diego, CA
Posts: 567
Likes: 0
Received 0 Likes on 0 Posts
Default RE: trex wobbles

Is this a "new" problem that developed after the heli had been working for a while (like after a crash or adjustment or something) or has it always done this since the first flight? Sounds like the same thing my Trex 450 SE it was doing when it was new. Turned out to be low head speed. If nothing is bent and everything is assembled correctly, blades are balanced and tracking ok etc, you may just need to up the head speed. What does your throttle curve look like? At mid stick it should probably be around 65-85%. A tachometer is a good idea also so that you know what your head speed is. I think the recommended head speed should probably be the same as the SE which is around 2600-2800.
Old 01-14-2008, 01:40 PM
  #6  
Senior Member
 
MiniCwik's Avatar
 
Join Date: Jan 2007
Location: New Baltimore, MI
Posts: 1,035
Likes: 0
Received 0 Likes on 0 Posts
Default RE: trex wobbles

Dohh, yeah head speed would be important ... not enough head speed and too much pitch could cause issues.

What are your normal mode curves?
Old 01-14-2008, 09:34 PM
  #7  
Senior Member
 
heliaction's Avatar
 
Join Date: Sep 2007
Location: Christchurch, NEW ZEALAND
Posts: 323
Likes: 0
Received 0 Likes on 0 Posts
Default RE: trex wobbles

How tight are your blade grips? Are they loose enough that they will straighten out when head speed is up?
Old 01-14-2008, 11:25 PM
  #8  
Senior Member
 
Join Date: Mar 2007
Location: Frederick, MD
Posts: 138
Likes: 0
Received 0 Likes on 0 Posts
Default RE: trex wobbles

I agree, head speed and blade grips are to tight. Have you checked our main shaft outside of the Heli? Are our servos tight to the frame, with no slop! do did you strip a tooth or two on the servo that is alowing for limited movement?
Old 01-15-2008, 07:23 AM
  #9  
Member
 
onad's Avatar
 
Join Date: Jun 2007
Location: Beaverton, OR
Posts: 87
Likes: 0
Received 0 Likes on 0 Posts
Default RE: trex wobbles

Yes, check that your main rotor blades are not too tight. I had this problem with my SE V2. I had to sand down the new Align CF blades where they attach to the grips. Just took the paint off with an electric hand sander. Then the wobble problem went away.


Good luck!!

ORIGINAL: heliaction

How tight are your blade grips? Are they loose enough that they will straighten out when head speed is up?
Attached Thumbnails Click image for larger version

Name:	Hf97876.jpg
Views:	14
Size:	31.8 KB
ID:	851791  
Old 01-15-2008, 07:43 AM
  #10  
Senior Member
 
MiniCwik's Avatar
 
Join Date: Jan 2007
Location: New Baltimore, MI
Posts: 1,035
Likes: 0
Received 0 Likes on 0 Posts
Default RE: trex wobbles

I had to sand my blades at the end to get them to fit into the grips loosely, and then tighten the grips to the blades so that they can be moved with little effort.

Let us know what you find out, we're here to help.
Old 01-15-2008, 02:06 PM
  #11  
Senior Member
 
Join Date: May 2007
Location: San Diego, CA
Posts: 567
Likes: 0
Received 0 Likes on 0 Posts
Default RE: trex wobbles

Ah yes, I've had to sand the blades (325 pro woodies) on a newer SE V1 also. PITA. The 315 carbons on the other hand are plenty loose.

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are On


Thread Tools
Search this Thread

Contact Us - Manage Preferences Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.