Hi All,

I am facing this problem with my HBK2, It shifts its height suddenly up and down. I have charged the battery (new) and still facing the issue, I unplugged the motor and checked for any hickups in servo movements but that seems to be doing fine. Can't figure out the problem.

Thanks
Hellyflyer

One common reason why you see such issues in belted electric helis is the Van De Graaf effect (here is one link with details : http://www.eskimo.com/~billb/emotor/belt.html), and other types of glitches introduced by interaction of electric charges.

This causes charges to build up, and while discharging, it causes the receiver to brown-out / glitch.  I had this problem for the first couple of weeks with my first heli (a Trex 450 SE), and solved it with a combination of the following.

1. Adding a ferrite ring to wire that goes from ESC to receiver.

2. Rewired the heli so that the the receiver and related wires are away from the ESC and motor.

3. Moved from FM/PPM to FM/PCM.  PCM is more resilient to such glitches (actually it masks most of glitches, and when something really big hits, you lose all control; as compared to PPM which exhibits the small glitches but recovers as the charge subsides).

Others have tried lubricating the tail with appropriate lubricants, as a solution; or providing "earthing" to components like the tail pulley (this all depends on your isolation of the issue).

The big question is, is the jump periodic ? That is, it works fine for sometime, then jumps, then works fine for sometime and so on ?

Bingo,

I recently wrapped the antenna wire on the knight rods on the tail boom of the heli I think its because of that. i will change the wiring and will let you know. btw what is a ferrite ring? and from where will i get it.


Thanks
Hellyflyer

You can see the ferrite ring with the ESC to receiver cable coiled a few times through it in this post :

http://www.rcindia.org/helis/build-and-review-the-align-trex-500-esp-part-2/msg373/#msg373

It is basically a noise filter, and is found in some digital-camera-to-USB cables etc :

http://en.wikipedia.org/wiki/Ferrite_bead

Not sure which Indian stores carry it, I was hoping to see it at Rotor Chennai, but it is not there.  You can always get it from international stores.

Thanks Anwar,

Is there a specific size which I am looking for?


HellyFlyer

Since we are all Align fans here for the most part, we have been using that one, and we only come across that one size.  I am sure there are others, but they should all work similarly.

RC Dhamaka used to carry ferrite rings.. Check with them..

- Chan

They still have the big ones, whatever big is ! 

I have been using these : http://www.google.com.qa/search?hl=en&source=hp&q=align+ferrite+ring+K10331A

I think I had to take the 3 wires out of the plastic connector (by *carefully* lifting the small plastic tab against wire), rolled the wire a few times (like 4) and then put the connector back in.  Remember that it is easy to break the plastic tab/lock while doing this, so be careful.

This thread on RR has good information and pictures on this subject :

http://rc.runryder.com/helicopter/t223571p1/?highlight=ferrite+chokes

Hi

If you have a ubec or bec, try using a ferrite ring where it plugs into the Rx... bec can generate a lot of RF noise also called as interference with other rf devices. Look if your esc is getting hot, It could be a internally short circuited ESC...

Hi Anwar,

Thanks for the RR link it has some wonderful explanation and pics.

PS - I have still not got a chance to fly my HBK2 after wrapping it on the skids so was not able to check if my ESC is getting hot will keep in mind.

Thanks Again
Helly Flyer

Hi All,

I tested my HBK II with the antenna wrapped on the skid and I kind of installed a little ferrite ring which I took out from TV antenna plug I don't think its effective as I was not able take the wire through the hole so I am still searching of a ring with a bigger hole. So the problem still exists it still changes height frequently with little jerks the ESC is not getting hot I am posting some pics for you all to see. Can it be because of the joint in the main frame?

I think we have jumped the gun a bit on this, mainly because my question to you below has so far been unanswered.

Quote from: anwar on January 03, 2010, 07:36:08 PM
The big question is, is the jump periodic ? That is, it works fine for sometime, then jumps, then works fine for sometime and so on ?

We need to understand what you are experiencing, in a more descriptive fashion (preferably with a video).  How big a "jump" are we talking about.  Do you feel you have full control of elevator/aileron/rudder even during the jump (remember, the "jump" is mostly about "pitch") ?

If you can feel/force vertical movement of the head with the body of the heli fixed, that would be a reason why you have this.  When you try to pull on the head (no, not the "swash") by holding the landing skid (roughly speaking), you should NOT feel them coming apart.

And one thing you need to check is how big of a gap do you have in the highlighted area (in red color) in the attached image. If there is no gap, see if you can manually make a gap by gently pulling apart the head and the landing skids.  If you are able to, that is bad.

Typically, there should be no gap there.

Secondly, wrapping the antenna like that is a bad idea.  It effectively reduces your range significantly (although this is probably not having a direct impact on the issue at hand).

Hi Anwar,

Yes the jums are frequent may be a mili second difference i think the best way would be to show you on a video of the same, I will post really soon.

I was unable to make a gap in the highlighted area by gently pulling the skid and head in the opposite directions which is good. I am always in control of the heli even when the jumps are happening just that I have to change the throttle input to keep it on the same height also the jumps are not in one direction sometimes it moves up and some times it comes down.

Also How would you suggest I wrap the antenna?

Thanks
Hellyflyer

If these are the symptoms, then it is probably not an charge build up and/or resulting radio interference issue.  The charge build up issue would happen at like regular intervals of many tens of seconds or even minutes, and you tend to lose control for like couple of seconds.

If the jump is present all the time, then it most likely is mechanical, and you have to hunt it down.

About the antenna, the Trex 450 came with a hollow plastic tube to extend the antenna towards the back, like at the bottom pictures in this thread.

http://www.zerorc.com/align-t-rex-450s-build-notes

You can always take it towards the tail using the one of the boom supports, and then let some part just hang. If it is too long, wrap around couple of times, but take the rest towards the tail and let it a small length drop before it reaches the tail motor/rotor. The longer you are able to have it in a single piece, the better your reception.



Just to confirm one more time, does the heli jump around all the time ?

Hi Anwar,

Please see the video of the Heli.




Thanks
Hellyflyer

May be I am not looking enough, but I did not find it "jumping" It looked more like someone struggling at the controls, as if they were trying to hover in one place, like the case when one flies under somewhat significant winds.

Yeah it was windy today, But i think it does jump at 0:27 to 0:34. Well I guess this one does not have enough jumps. I will post another one tomorrow.


ALso I wanted to know that there should be no movement at the part you highlighted in red earliar as I see there is very littler movement there. What adjustments should I make so that there is no movement.


HellyFlyer.

Saw the new video here : http://www.rcindia.org/helis/heli-videos-anybody/msg12433/#msg12433

Again, I did not find anything unusual

And regarding the small play / slop on the main shaft, see part number "061" ("Set collar" with a grub screw) in the manual (http://www.hhq.com.au/store/downloads/hbk2_manual.pdf) on page 18. You want to loosen that, pull up on the whole head, push the collar down as much as possible, then tighten the collar in place with the grub screw (part "005" in the same page) again.

Sorry this is a little off-topic, but how is the overall quality of the HBK Heli ? A newbie was attracted to the low price of it, at HobbyCity and asked me my opinion on it. I believe this is the same as here : http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10413&Product_Name=HK-450MT_CCPM_3D_Fully_Alloy_Helicopter_Kit_(Align_T-Rex_Compat.)

So would this be recommended for a newbie ? I guess there's a Heli craze starting to build up where i fly !!

This one is an alloy upgrade of the HK450 discussed here :

http://www.rcindia.org/helis/looks-like-a-great-deal-on-a-450-clone-heli/
http://www.rcindia.org/helis/is-this-the-cheapest-trex-450-clone/

The original one has couple of issues, calling for upgrades to certain parts. 

Since this is an upgraded version, hopefully those issues are resolved.  No way to confirm unless someone tries.   The price is sure attractive.

For someone to start flying helis using a machine of this size and flying characteristics, make sure that he has quite a bit of time on the sim, and have the heli built by someone who is experienced. If the flyer is an absolute newbie to flying, then expect to spend some money on parts !

Quote from: anwar on January 22, 2010, 08:41:38 AM
Saw the new video here : http://www.rcindia.org/helis/heli-videos-anybody/msg12433/#msg12433

Again, I did not find anything unusual

And regarding the small play / slop on the main shaft, see part number "061" ("Set collar" with a grub screw) in the manual (http://www.hhq.com.au/store/downloads/hbk2_manual.pdf) on page 18. You want to loosen that, pull up on the whole head, push the collar down as much as possible, then tighten the collar in place with the grub screw (part "005" in the same page) again.

Hi Anwar,

Thanks for letting me know how to go about tightening the bolt and the manual details (that helps a lot)

Howver the video which you saw in the "any heli videos post" is of my Belt CP V2 and not my HBK2. I am working on rebuilding the head to make sure that the shift is not because of the head alignment.

Thanks
Hellyflyer

Oops, sorry about that ! Since you said you will post another video, I overlooked the details

HI Anwar,

Thanks for pointing me in the right direction the fault was mechanical. The problem is now fixed after I rebuild the head and did all the alignment.


Thanks for all your Support

Take care
HellyFlyer