Trex 450 V2 Pro 3gx slop in head, swash tilting right

Started by Ajay JM, December 10, 2011, 06:48:07 PM

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Ajay JM

Apparently having a bit of problem with my 450's head.

http://www.youtube.com/watch?v=jcWN2DBNQ60&feature=youtu.be

Level Swashplate at throttle up without blades
http://www.youtube.com/watch?v=5qTlR2821O4&feature=youtu.be

Any thoughts buddies, on why the swash tilts right abruptly on spool up when blades are put on?
Awaiting the next tornado to fly my kites..

anwar

Some amount of play is expected, and I am not sure if what you are demonstrating is truly out of the the range of acceptable. After all, you are just pushing your feathering shaft against the rubber dampers.  Make sure you have put the right number of dampers (which depends on their types).  To be honest, I don't think what you are seeing if going to be an issue in flight.

And I can't see any "swash tilts right abruptly" in either of the videos.  What are you referring to ?

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Ajay JM

#2
Hi Anwar

I was trying to say, as I put the blades on and spool it up, the swash tilts right-meaning on loaded condition it tilts right. In the video, it isn't tilting since the blades are not on.
I'm using stock dampers now.
I'm afraid I couldn't put a video with the blades on.

I took the heli out today and tried to raise it in the air; the swash tilted right abruptly and the heli plunged sharp right. I scraped the blades hard on concrete and chipped the edges of my new align CF blades. Was able to zero down the throttle fast enough, preventing further damage.
Not sure this has something to do with the 3gx controller now;however it did not reset or anything.
Dunno if adding a bec or updating to next version may help.
Awaiting the next tornado to fly my kites..

Hellyflyer

it seems that your sevro is acting up on load just check the servo for any missing teeths
Helis and Quads ROCK !!

Ajay JM

Not trying to justify the servos but matter of factly, these are brand new align DS 410 metal geared servos. Again, I am not too confident of 3gx after browsing through a bit; it could be that 3gx is overcorrecting for minute vibrations.

Need to pin this down soon. Hope I don't end up with a totaled heli in that attempt :-\
Awaiting the next tornado to fly my kites..

anwar

OK, now the issue is clearer. 

The first thing to check is the direction of your compensation for aileron (and elevator).  Have you confirmed that when you tilt the heli on its sides (without any throttle applied), the swash tries to remain level ?  Do the same tilt check on nose-to-tail tilting also.  This is a basic step for setting up any FBL system and I am sure you have done it, but no harm in reconfirming.

And do further tests in a grassy area !
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Ajay JM

Yup, had done that already during setup. Again, this is what I reconfirmed first when I observed the heli behaving strange on spool up. Swash tilts left when I tilt heli rite and vice versa to keep it level as expected. Same with elevator as well.


I had tried spooling up on the fluffy carpet inside ( a tolerable replacement for grass, though dangerous to inmates  :P) the house first before I had taken it outside. It behaved the same way and scraped the blades. No injury to the blades though, unlike when it hit the concrete.

I never encountered such an issue on my trex 500 or 550, both of which are on 3g. Ofcourse, the 3g still has  its own share of problems like sudden tail kick and stuff(more so on the 500 and very rare on the 550), but nothing like this. My desperation is forcing me to blame the 3gx  :banghead:
Awaiting the next tornado to fly my kites..

anwar

I would double check :)  The reason is that even the best make silly mistakes.  I still see people who have been flying for many years take off without checking if ailerons are reversed (no... not a reference to anyone in particular on this forum ;D ).  Because the behavior is consistent with the symptoms if  this was true.

The next thing is to check and eliminate any source of vibrations on the controller, including trying another mounting tape if needed or moving the unit to some place closer to the main shaft (as vibrations are amplified on the edges of the frame).

Also, make sure your pitch/throttle curves allow for enough head speed before the heli tries to lift off.

Lastly, your 3GX unit might be faulty. 
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Ajay JM

Quotemoving the unit to some place closer to the main shaft

I wanted to place the 3gx where my futaba r617fs is sitting right now(behind the anti rotation guide)

Unfortunately, the r617fs is tad wider than the space between the frames so I had to place it either on the side of the frame or on the top. It is taller as well, so I cannot keep it vertically inside unless I remove the 3gx support board which in a way gives support to the frames. Else I will have to move to spektrum sat receivers.

I really didn't want my r617s bulging out on the side, so I had no option but to keep the 3gx in the inverted position inside the frame and R617fs on top.

I'm using the stock align mounting pad for 3gx(Had tried scotch mounting tape first). Aileron directions are also correct.
Pitch and Throttle are both set at 0,25,50,75,100% on F7C. Maybe I will try raising the throttle curve for the same PC and see if that makes a difference.

And Anwar bhai, I always make mistakes and I'm mostly best in making them  ;D (however, for the others in the forum, trust me I'm not the one who kept reversed ailerons before I flew)
Apparently, I'm only quarter way up the ladder in RC; sure I know some of you who are on the top rung. So I always look up to advice from people like you.
Awaiting the next tornado to fly my kites..

anwar

The default throttle and pitch curves are usually not a good combination.  Try using a throttle curve like 0,45,65,85,100.  This one ensures there is enough throttle (ie headspeed) before higher pitch ranges are reached.

And go very slowly when you increase throttle, just to account for any slow start and timing settings on the ESC.
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Ajay JM

Yea, tried that after I put the previous post. Still not helping :(
Awaiting the next tornado to fly my kites..

GreenDragon

Ajay,

Did you ever get this problem figured out?  I am having a similar issue with my 3GX unit installed on a Thunder Tiger Titan X-50.  On spool up the swash will start to tilt and sometimes the rudder servo will travel to it's extreme end.  I am now testing it with the main blades off so I don't damage the heli. Anyway it's like the 3GX decides to establish a new neutral point at some random swash position.  I tried different mounting tape, repeating the setup, freshly charged batteries, you name it.  Very frustrating!

GD

Ajay JM

Not yet GD, I have rebuilt it completely and put the 3gx behind the antirotation guide instead of in the heli's belly. I did this to see if it had something to do with vibes or position of 3gx. However, I've not gotten time yet to test it again.
I observed the same behavior that you did, except that I could not even take it up in the air before the swash tilted. Were u able to get off the ground even once? Since it doesn't seem to be an isolated one, advise forum members to investigate well before buying a 3gx. I will post my findings once I get time to test the rebuilt setup.

If it still doesn't work, I'm gonna send the 3gx as a new year gift to Align  :-\
Awaiting the next tornado to fly my kites..

GreenDragon

Ajay,

No I didn't even get it in the air.  It was just spooling up when the swash tilted and the tail went bonkers.  Luckily I was able to save it.  I tried once more with the same result. In between tries I had to cycle power to reset the unit.  I had tried an earlier version of the 3GX my buddy had.  He flies for Align.  I was able to at least fly with that one but experienced the swash tilt in the air twice.  Again I was able to bring it in safely but barely.  I was assured that this was a known issue that was fixed in the newer versions so I went ahead and bought one.  Now I have one that won't even let me get off the ground.  I contacted my friend and he is going to look at it this weekend for me.  If he verifies that the unit is working wacko at least I should be able to return it the hobby shop that sponsors him, also from which I bought it. As I mentioned I tried all kinds of different things to see if I could isolate the problem but always tested with the blades removed.  Some guys on rcuniverse are suggesting static discharge inside the case causing problems.  I'm not going to remove it from the case unless I end up being stuck with it.  I'll let you know if we get anything figured out this weekend. 

GD

Ajay JM

Any updates GD? I didn't get time yet for testing. How abt u?
Awaiting the next tornado to fly my kites..

GreenDragon

Well some guys on rcuniverse had some thoughts about static discharge. So I grounded the boom and tried removing the cover of the 3GX as that is conductive.  No luck! I eventually returned it and got a Beastx. It works great. I also have a Tarot unit from Hobby King which works great on my HK450GTPro if your looking for something to replace the 3GX.

Ajay JM

Got some time today and checked out everything from beginning. Nothing looked odd to me. I removed both tail and main blades and took the throttle to 100%. No unexpected behavior from the tail or the swash. I put the blades back on, took it out and spooled it up. The heli tipped forward suddenly even before mid stick. I was quick enough to place it back to avoid any crash or damage and was successful.

Lots of people shouting in forums this is due to vibe sensitiveness of 3gx and I need to take off real fast. Never had such kind of problems on either of my 3g sensors(mounted on trx 550 and 500) though. I'm a bit scared that I might end up in a bad crash if I do that.

Anyone here with 3gx yet facing similar issues?
Awaiting the next tornado to fly my kites..

anwar

Have you tried mounting it with a metal plate damper between two foam tape pieces ?

Can you post a close-up pic of exactly how the 3GX unit is mounted ? I mean without changing/unhooking anything.

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Ajay JM

Well, tested my luck again today morning on greener pastures. Like mentioned in forums I took off fast as soon as skids started getting light, the heli lurched forward and then plunged backward, dug into the ground with its tail and fell aside. I must be very lucky, no damage on first inspection, just a little bit of dirt on the main and tail blade edges and probably a bend feathering shaft worst case.  Yet to do deeper scrutiny.

No Anwar, Iven't tried the metal plate.
(That's how my 3g is mounted on the 500). I did not want to waste another align tape (I used one when I mounted the 3gx first in the heli's underbelly) since I'm still testing; I'm using one piece of 3M tape alone. People have had good results with 3M anyway. Here's a pic taken on mobile. Not sure if that's close enough
Awaiting the next tornado to fly my kites..

GreenDragon

Ajay,

Try this...power up the heli and wait for the 3GX to initialize.  Walk around the room with carpet and come back to the heli and just touch the 3GX.  If it resets and the LED's go through the startup cycle again, the unit is bad, end of story.  Mine was acting exactly the way yours is and I tried every combination of vibration isolation (including metal plate between foam tape) and nothing worked.  There is a well known history of the 3GX resetting in flight as well.  The belt in the tail is a very good static generator and so is carbon blades cutting through the air.  Check out this link for more info. http://www.kempley-helicopters.com/guides/trex-500-electrostatic .  So even if you managed to get the heli off the ground there is a good chance it might reset in the air.  Also check out this forum on helifreak http://helifreak.com/showthread.php?t=325379 .  There is a lot of info there.  Start reading around page 30 to see what I've been talking about.  As I said before I have a Tarot unit on my HK450GT Pro and it works great.  I think they're around $45 now.  For me, my 3GX was too great a liability so I replaced it.  Having said all that, a lot of guys are having great success with the 3GX out of the box and that's great.  But it's been the experience of myself and many others that if they don't work out of the box, (assuming they are actually setup correctly) they probably won't no matter what you try.

GD

anwar

With that feedback from GD, I am not sure what to say :(
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