Tail Kicking

[c.penhallurick]

When I spool up my 500 a get a big tail kick to the left. Every time at about half stick.
When I am flying I get little kicks also but only very small ones, usually when Im on the throttle about alf stick. 80% throttle curve, 13t pinion.
If the battery gets a little low I get a piroutte, tail to the left by about a quarter of a turn.

Im running a 401, 9257, voltage regulator and the speed controller is set at 6v.
Mt throttle curve in normal flight mode is from 70%-100. Even if I start in this mode by releasing the throtle hold in soft start it will spool up smoothly but as soon as I take it to about half stick it kicks.
If i set the curve to 100% all the way through and spool up by releasing the throttle hold it will kick at about the same point.

Ive set the gyro up in rate mode etc and appart from the problem its solid in both rate and eading hold.
JR9X. Jr Reciever. Quick UK base loaded antenna.

I also have the screeching noise if that would make a difference.
Im now worried about flying.


Any ideas please?

[Finless]

1) Make sure your gyro is as far back on the block as possible. Many have had this problem picking up noise from the tail drive bearings.

2) You might have a static problem some are seeing. If it appears to be related to RPM only and not random then it's bearing noise effecting the gyro. If it's totally random then maybe static.

Bob

[c.penhallurick]

Im sure it isnt static I have anti static lube etc. Its also not random. I'll try moving the gyro back at I had placed it inward for better protection. It does tend to happen at the same rpm. Is there a bearing fix I can do?

Thanks for the advice by the way...Apreciated. Its been driving me up the wall.

[Finless]

This is common even with the 600. The sensor used in newer gyros coming out in the last year are more sensitive than the older units. I have seen this happen on at least 10 600's and a couple 500's now. Better bearings may solve it I don;t know as I haven't tried that myself. But moving the gyro all the way back has solved it pretty much 100%.

Bob

[c.penhallurick]

Cheers Bob. Have a good evening. Or is it day in America? Either way. Thanks.

[lightning rc]

Chris did you move to a bigger tail servo horn like I told you ?
I had the same problem on my 500 with S9650 and 401 , I was running the samll round horn which also use on my 450 , found I needed the size which on my 600 but a hole in .(sorry for no sizes)

[c.penhallurick]

No I didnt Mate. Ill try that next. Before I sell it !

[Socal500]

This sounds like the same twitch I had and at the time I was lubing the belt. I noticed it when going either side of around half stick on collective. I did not have the other symptoms you mentioned. When I grounded the tail shaft, boom and front pulley shaft it went away.

[c.penhallurick]

Uncle Bob;

Moved my gyro back.... Problem solved. Gone. Adios...
Thanks!!

[Finless]

Glad I could help! I kind of knew that was the issue as again I have seen it at least 10 times now.

Bob

[CT Aviation]

I have a very similar issue but only when gyro in HH mode (401). In normal mode the tail sits there fine but when in heading hold it twitches as though it's going to wag. So far I have grounded everything, the gyro is about 5mm from the back of the shelf, I have tried less gain, higher and lower headspeeds and stripped and re-greased the tail thrusts.
It isn't anything too severe but would like to fix it.
regards
Chris

[psindrup]

Uncle Bob;
Moved my gyro back.... Problem solved. Gone. Adios...Thanks!!

Where did you move the gyro from (and to) - pictures please. :lol:

T.i.a.

Peter

[Socal500]

Where did you move the gyro from (and to) - pictures please. :lol:

T.i.a.

Peter

I think they are referring to moving it back towards the boom and away from the bearing. If you look at the top right corner of the gyro you can see the bearing in the background. Grounding fixed mine but at one time my gyro was forward more. It use to be almost up next to the bearing. This is where I have it now and it could probably come back right to the edge. Im assuming this is what they mean.

http://www.socalsurfs.com/trex500/gyro.jpg

[c.penhallurick]

Sorry for the late reply. Yes I moved itvright back as the pic above. I had it closer to the bearing. The move was only about 10-15mm but it made the difference. Ialso dropped a tiny ammount of teflon lube on the bearings. Only a tiny ammount though, you dont want to wash them out.

[psindrup]

Sorry for the late reply. Yes I moved itvright back as the pic above. I had it closer to the bearing. The move was only about 10-15mm but it made the difference. Ialso dropped a tiny ammount of teflon lube on the bearings. Only a tiny ammount though, you dont want to wash them out.

No reason to apologize - thanks for the feedback :thumbup:

Impressive that 10-15 mm can do that much if a difference ...

Peter

[markswift]

I have a very similar issue but only when gyro in HH mode (401). In normal mode the tail sits there fine but when in heading hold it twitches as though it's going to wag. So far I have grounded everything, the gyro is about 5mm from the back of the shelf, I have tried less gain, higher and lower headspeeds and stripped and re-greased the tail thrusts.
It isn't anything too severe but would like to fix it.
regards
Chris

Hi Chris, if you're still having this issue, here's all the things I did to cure it (some of which I think you already did)

1. Earth ESC feed -ve to motor mount

2. Silicon spray belt (don't think that helps, just good pratice)

3. Rebuild tail & grease thrust bearing (again, don't think this has any bearing on the issue, but needed to be done)

4. Install metal hex nuts in tail assembly (made bugger all difference)

5. Changed gyro tape to 3 layers of Halfords 1mm number plate sticky pad things.

I now have a steady tail with a gain of 30%.

I do have a very slight bounce after small tail movements, strangely not so much after harsher ones and I take this to be down to having a 9650 on the tail which I may seek to cure with a proper tail gyro say a 9256. This doesn't effect the chucky 'roundiness of the heli :)

I am convinced that the biggest contribution to the above is the number plate sticky pads - only £1.99 a pack as I recall. I did try the 6mm ones, but although that worked, I felt there was just too much cushion there.

By the way, I have always had the gyro right at the back of the plate as in the pic above..

Hope this helps
Mark

[psindrup]

3. Rebuild tail & grease thrust bearing (again, don't think this has any bearing on the issue, but needed to be done)

Replace the trust bearings in the tail with 3x8x4 mm radial bearings.
It makes the tail blade grips much more stiff, and I have read several posts, that it fixes the last tail wag.

I have just done that myself, but I have not had a chance to test fly it, due to bad weather and to much work. ;)

Peter

[markswift]

Peter,

I'd be very interested to hear what difference the radials make. I have a spare tail, so that would be an interesting experiment....

Mark

[psindrup]

Peter,
I'd be very interested to hear what difference the radials make. I have a spare tail, so that would be an interesting experiment....
Mark

Mark

As you can see in my signature, I am a 100% n00b, and I am still leaning to fly, but I had a little "wag" on my tail no matter how I set my Spartan ds760 gyro.

But just the "feel" after you replaced the bearings, made me think that this was right. :thumbup:
No slop or wobbling in the tail blade grips what so ever after the replacement.;)

I am really looking forward to my next flights - probably next weekend, and I will let you know how it works out.

Peter

[CT Aviation]

Mark, thanks for the tips, I have moved the gyro back right to the edge with no effect, grounded and lubricated everything with no effect (strange that in normal mode it dosen't do it, only in heading hold)
I flew it Sunday and upped the head speed even more which semed to cure it, 70% gain and no wag, even did a couple of loops and rolls (not pretty but no crashes)
i think I may change to the 13 tooth pinion next as headspeed is limited on the 12 tooth even running 100/95/95/95/100 throttle curve in idle 1.

Chris

[markswift]

But just the "feel" after you replaced the bearings, made me think that this was right. :thumbup:
No slop or wobbling in the tail blade grips what so ever after the replacement.;)
Peter

Guess what I'll be ordering tomorrow then :)

[psindrup]

i think I may change to the 13 tooth pinion next as headspeed is limited on the 12 tooth even running 100/95/95/95/100 throttle curve in idle 1. Chris

Why don't you try to run 100-100-100-100-100 with 12T pinion first?

Peter

PS: And see my post about tail trust bearings.

[markswift]

Mark, thanks for the tips, I have moved the gyro back right to the edge with no effect, grounded and lubricated everything with no effect (strange that in normal mode it dosen't do it, only in heading hold)
I flew it Sunday and upped the head speed even more which semed to cure it, 70% gain and no wag, even did a couple of loops and rolls (not pretty but no crashes)
i think I may change to the 13 tooth pinion next as headspeed is limited on the 12 tooth even running 100/95/95/95/100 throttle curve in idle 1.


Hey - you just described all my flying to date - not pretty but no crashes - I like it!!!

I'm running a 13T - I got a vertical nod on the 12T, but I'm impressed you got 70% from the gyro - if I go above 35% I get wag (and mines a 401 too).

So now I'm thinking it's a combination of headspeed, type of tape, and earthing the esc to get rid of the emitted emi, and also as Peter says above, I'm going to try a radial bearing on the tail.....

Mark

[CT Aviation]

I,ve only got 17 flights on the 500, about 30 on a century Mini Pred and got to this same level on a rapter 60 some years ago before giving up. this time there is no giving up !
let me know how the bearings go, i was going to wait until i trashed the tail and then upgrade to metal tail box, by which time there maybe upgradrd tail grips ?
I think sundays flying was better as I could not feel my fingers at all due to the cold !!!
Chris

[markswift]

I'm going to order the bearings tomorrow - only a couple of quid from Midland Heli, so I'll let you know. Also, I believe Quick UK will be making a 500 tail soonish...

My fingers nearly turned blue flying this evening :)

Mark