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500 Class Electric Helicopters 500 Class Electric Helicopters manufactured by Align, Tarot, SYMA, Airhog, Chaos, HK and similar.


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Old 05-07-2012, 03:40 PM   #1
Lee777
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Default Trex 500 tail drift????????

Hi All,

My heli's head drifts very slowly to the left?? i have a dx7 and futaba gy401 gyro, its only very slight but is there a way i can stop this drift?? any ideas what the problem could be? cheers all.
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Old 05-07-2012, 03:51 PM   #2
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It is a mechanical problem, try this :
http://www.rchelisite.com/how_to_set...gy401_gyro.php

Spool up your heli and bring it into a low hover – you’re going to need to provide left or right rudder input to keep the tail steady. If you don’t want to hover your heli, you can spool it up and get it light on the skids on a very smooth surface until it’s just about to take off – though the rotor wash can come into play here. Make a mental note of which way you need to apply rudder input, land your heli and adjust the pushrod length to compensate for the rudder input you had to give.
Keep adjusting the length of the pushrod until your heli will hover and the tail will hold without any rudder input.
...........

Also, is your swsahplate level?
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Old 05-07-2012, 04:11 PM   #3
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Swash is level. i thought the gyro should correct this drift if the push rod is just slightly out???? the tail blades are centered when the servo is at center?, its only very slight, when in hover it takes about 25 seconds for it to turn 90 degrees to a side on hover
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Old 05-07-2012, 04:30 PM   #4
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Usually a vibe issue, or the gyro placement could be an issue, picking up excess vibes from its mounting. I'm assuming you played around with the gain???
I honestly approach tail drift as a vibe issue usually. re-pad the gyro maybe, recheck your tracking, put the gyro into rate, spool it up and look down at the tail blades.. see that they are spinning and tracking really well...in rate mode, those tail blades should look like a knife edge. I set a flat 0 pitch curve in normal, switch to rate mode and spool it up slowly watching the tail blades. This will either confirm or disprove a tail issue like unbalanced blades, bent something or other, failing bearings..
Could just be your gyro needs to be moved to a more isolated spot???
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Old 05-07-2012, 04:31 PM   #5
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Oh and check for slop in the tail servo.. if you've had it awhile, sometimes the gears develope slop and wont recenter right under load as opposed to static testing.

Last thing.. ( I know you dont want to hear this..) but I have heard of this issue with the 401 a few times... you could always try the Quark or even the Spartan DS760. Both are failrly cheap now, and I still fly the DS760 on two of my 500's.. the things are rock solid....not that you need to buy a new gyro.. but just in case.. these two are my hardcore referenced gyro's.
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Old 05-07-2012, 05:40 PM   #6
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What servo r u using?
Check for vibration.
Check main shaft, feathering shaft, tail, weight main blades and track'em.

http://www.helituning.com/index.php/...401-setup.html
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Old 05-07-2012, 05:59 PM   #7
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I went through this a few years ago, and determined that adding a 470mf capacitor to the BEC rail eliminated the drift. The switching BEC that Align uses is a bit noisy and the 401 did not like it. The Spartan DS760 I put on it later did not have the issue.

Your issue, however may be different.

The DS760, or the quark, are excellent gyros and since peeps are going FBL, they can be had used, for a song. You might consider an upgrade.
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Old 05-08-2012, 09:55 AM   #8
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Before all of the above suggestions - I might ask if you are in Rate or HH mode on the gyro? If you are in Rate mode -more mechanical adjustment is needed as described above. If you are in HH mode I would suggest something is loose on the tail or binding.
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Old 05-09-2012, 07:37 PM   #9
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Set up! Set up! Set up!
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Old 05-10-2012, 01:22 AM   #10
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When I have had a drift to the left it was always one of two things. I was either in HH or excessive vibrations. I finally cured the vibration problem by changing the mounting foam to a thin pad/metal plate/thick pad when it was on the boom block or just the Futaba gray foam and mounted on the tray below the boom block. Oh yeah and I got a Quark.
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Old 05-11-2012, 05:00 PM   #11
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HeliDirect just droped the price of a new Outrage Quark to $90.....not as cheap as that Christmas special all of us bought out.. but its a great price for one of the best.....

Sorry.. I just couldnt help it....
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Old 05-12-2012, 01:59 PM   #12
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Ok ok u convinced me to get a quark!! put new foam tape on gyro and first pack all was good no probs at all tail held solid, then landed and put in second pack, got it off the ground and it was like i was in rate mode!!! tail was all over the place just uncontrollable nearly binned it, very close to a major turf tuft ! this gy401 is brand new only about 5 packs through it! why problems already?? anyway whats the best deals on the spartan gyro's youve seen? what gyro will do the job for a trex 500 and hold that tail solid?? cheers all..
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Old 05-12-2012, 03:16 PM   #13
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As much as I love the Spartan gyro's... I really think you need to make sure you don't have other issues before spending the cash on a Quark then finding out later something else is wrong. You should be doing a total investigation, looking for binding, tail servo issues like a stripped gear, vibration, ( which will affect the Quark as well..) OWB slipping, etc.
That said, .... You can get a used Quark pretty cheap in the for sale threads...Heli Direct has the "Outrage" edition for $89.. or.. you could even go cheaper and look for a used Spartan DS760. I still fly two of these gyros...they were the "go to" gyro.. then they shrunk it down and called it the quark. Of course they have made changes as well.. but unless your REALLY throwing down.. you wont notice any difference. My DS760's are rock solid..no matter what...wind, hard tight maneuvers...right now, they are going for around $65.. I bought one as a spare last week for $55. Its not the most up to date Spartan out there.. but miles better then most gyro's.
For a new one.. I think Heli Direct has the lowest price....BUT....
Please... don't let us talk you into a gyro, until you do a proper investigation into your issue. The GY401 is a very good gyro.. and should work right, if things are set up right. Look to make sure the gyro IS the problem before spending the money.. otherwise.. you could spend money on a gyro, then have to spend money on the real issue if the gyro wasn't it....do you have another gyro to try out first? A spare maybe?
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Old 05-12-2012, 03:18 PM   #14
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I run the GY401 on my 500 with very good results. The gyro may not be the problem here...
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Old 05-12-2012, 03:32 PM   #15
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Exactly.....
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Old 05-12-2012, 03:41 PM   #16
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I dont have another gyro to try and round here where i from i dont know any1 else who flies heli's , from what i have checked i cant see any binding, all seems smooth, i put new gyro pad on before todays flight, i havent checked the servo gears yet but will drop on that right away!, how come 1st flight was solid tail then 2nd was all over the place????? can the gyro get hot then not do as it should??? tail blades are lose, all blades balanced, just puzzling me bad now!!
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Old 05-12-2012, 03:57 PM   #17
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You need to approach issues with some system.. especially on these things...its easy to make guess's and pour money into it hoping you fix the issue, but making sure you no THE problem causing the issue really is important, otherwise you could spend more money then you need to and even get more frustrated.
Its hard to diagnose a gyro issue, if you dont have another to try, but in ANY problem.. I always try to eliminate all other causes if I can. With a mis-behaving tail.. theres alot to look at including the gyro.
Have you tried to disconnect the motor wires, bind the heli, and do a gyro correction check? Moving the tail and seeing what the gyro and servo do? See if somethings not working properly? See if the tail servo is jumpy or slipping? Does the tail servo get hot? ( over worked from binding?) Sure its kept still while your binding it? ( gyros sometimes can have issues if the heli is moved or bumped while its binding )
Next you could take the main blades off and spool it up and check for vibrations...alot of the time, an erratic gyro can be a sign of vibrations. Just a few ideas.... but you get the point.....
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Old 05-12-2012, 04:30 PM   #18
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Just checked servo and gears are all fine, tail blades all look ok, tail gear with the umberella gear on is very slightly bent can see a slight wobble when i spin main blades (but must have been like that on the 1st pack when all was good) will re bind it tomorrow and see how it goes, and re lay the gyro on new foam tape, gyro is on the boom block gyro gain on tx is 73. cheers for comments, i WILL get there in the end
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Old 05-12-2012, 07:02 PM   #19
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A drifting tail is most likely a vibration issue-- even if you have a Quark.

Listen to what the others have said. There have been some very good points made.

You already said in the preceding post that the you can see a wobble---fix it.

Just because you got a flight without problems, don't assume a wobble is ok. You need to fix head and tail problems. These things will drive gyros crazy!

Otherwise you will be pi$$ing your money away (pounds, euros, or $$, doesn't matter).
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