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Jul 12, 2021, 09:19 AM
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Microbeast tail stability issue again


I converted my "old" TT Raptor nitro heli to FBL using Microbeast Plus fbl controller but unfortunately I have strong tail stability issue which finally caused a crash.

I have been reading forums searching for the solution but still not have found it.

The issue is the following:
The tail of the heli slowly drifts to the left. And sometimes it starts rotating around. Once it rotated around 3 times when I can finally stop it and land. But after several trials and errors I crashed it, it was not possible to stop the rotation. The slow drift is always there but the continous rotation seems to be random. I can hoover at the same position for several minutes then suddenly it starts rotating around. And again and again.....

-The raptor was flying without any problems with a Gy401 gyro and a Futaba 9254 servo.
-The frame is nearly new, there was only a few flights with the flybar system. So there can not be bearing issues.
- Blades were balanced and leveled
- main shaft is straight (or at least it was until this crash, have not checked yet)
- FBL head is new
- belt is tight
- all mechanical components moves smoothly
- new swashplate servos
- 9254 on the tail (hardly any usage)
- no visible vibration ( there is also no foam formation in the fuel tank)
- all servo related parameters were set up based on Microbeast's servo database
- everything moves and compensated in the intended direction (I could fly with it a few rounds)
- the heli is stable horizontally expect for this rotation to the left
- I also tried to change the tail gain until the tail started to oscillate but it had no influence on the drift to left. The tail was bouncing but still drifted to left.
- at first I used the original mounting glue but later replaced to another one. Did not help.
- I upgraded the firmware 1-2 months ago, I know there is a newer one but I think the existing one also should work.


Some people use different glues, attached a steel plate to the microbeast to add weight and try to tune the natural frequency or strap down the unit to the frame. And also try to fix the servo cables on different ways.
Sometimes these solution works but sometimes not.

I fed up with trials and errors. I give a last chance to this unit before dropping it to the waste bin, replacing the broken parts and convert the heli back to flybared.

So if you have any solution please let me know.
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Jul 12, 2021, 12:26 PM
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You could put the 401 back on to control the tail and the Microbeast to control the head. That is if you trust the Microbeast enough on the head.
Jul 13, 2021, 07:31 AM
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Thread OP
Quote:
Originally Posted by Roto Rob
You could put the 401 back on to control the tail and the Microbeast to control the head. That is if you trust the Microbeast enough on the head.
I do not really want to use 2 devices. If I put Gy401 back I will remove Microbeast and convert the heli back to flybared.
Jul 26, 2021, 01:13 AM
Team JR/DFA, KBDD Team Captain
Ah Clem's Avatar
High frequency, low amplitude vibration is almost certainly the culprit.

Are the wires insulated in soft foam before the enter the BeastX? If they touch the side frames, boom, or any other part of the structure vibration can get in to the FBL unit.

I do this, even on electric machines but would not even think about a nitro without doing it.

Also, what kind of tape did you go to (I too, find the stock tape lacking). You might try two layers of the gray 3M tape.
Jul 27, 2021, 01:58 PM
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Thread OP
Quote:
Originally Posted by Ah Clem
High frequency, low amplitude vibration is almost certainly the culprit.

Are the wires insulated in soft foam before the enter the BeastX? If they touch the side frames, boom, or any other part of the structure vibration can get in to the FBL unit.

I do this, even on electric machines but would not even think about a nitro without doing it.

Also, what kind of tape did you go to (I too, find the stock tape lacking). You might try two layers of the gray 3M tape.

I have not tried it out yet but now I use 3M 4011 grey tape.

And made a sandwich:
- 1 layer 4011
- 3 mm steel plate
- 2 layers 4011
- MB

And everything is strapped down.
Jul 27, 2021, 11:50 PM
Registered User
koppterX's Avatar
i have to ask what your transmitter gyro setting are on the beast X - if they are too high the tail will drift. mine are 44 across all flight modes on three different models and the tail is tight.
Jul 29, 2021, 04:24 AM
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Quote:
Originally Posted by koppterX
i have to ask what your transmitter gyro setting are on the beast X - if they are too high the tail will drift. mine are 44 across all flight modes on three different models and the tail is tight.

I use 58%.
But changing the gain not influence the drift.
Higher gain cause bouncing but the tail still drifts.
Lower gain results less bouncing but the drift is still there.
Jul 29, 2021, 02:40 PM
Registered User
I would get rid of the zip tie. I use a velcro strap or sewing thread.
Aug 02, 2021, 01:13 PM
Team JR/DFA, KBDD Team Captain
Ah Clem's Avatar
"And everything is strapped down."

The first thing to do is to get rid of the strap around the BeastX-that will transmit vibration directly into the FBL unit.

The next thing to do is to wrap the wiring right before it goes into the FBL unit in foam. If it touches the frame, it will transmit vibration directly into the BeastX no matter how much or what type of tape it is mounted on.

Below is a photo of my Sirocco. Note how the wires are wrapped all the way around in foam tape. I do this on both electric and nitro machines (with V-Bars, BeastX's, Robirds, and TAGS-Mini's and NEVER have a vibration induced problem.

This video is a bit fuzzy and admittedly the flying is not great, but this is my .90 powered Odin II with BeastX-the BeastX is solid as a rock:

Ah Clem and his Odin 90 (4 min 21 sec)
Last edited by Ah Clem; Aug 02, 2021 at 01:20 PM.
Aug 03, 2021, 02:58 PM
Registered User
Thread OP
Quote:
Originally Posted by Ah Clem
"And everything is strapped down."

The first thing to do is to get rid of the strap around the BeastX-that will transmit vibration directly into the FBL unit.

The next thing to do is to wrap the wiring right before it goes into the FBL unit in foam. If it touches the frame, it will transmit vibration directly into the BeastX no matter how much or what type of tape it is mounted on.

Below is a photo of my Sirocco. Note how the wires are wrapped all the way around in foam tape. I do this on both electric and nitro machines (with V-Bars, BeastX's, Robirds, and TAGS-Mini's and NEVER have a vibration induced problem.

This video is a bit fuzzy and admittedly the flying is not great, but this is my .90 powered Odin II with BeastX-the BeastX is solid as a rock:

https://youtu.be/b7LnWhOlshY
Thank you!
I will try it out.
I have wrapped the wires around with foam.

But from my point of view a device which needs these kind of trials and errors (different glues, combination of different glues, combination of different glues and metal plates, strap it down or no, wrap the wires with foam.........etc.) is useless. The user and installation manual do nor mention any of these tricks.
I have also contacted BeastX but there is no answer at all for weeks. That is all about their customer support.....
Aug 03, 2021, 10:49 PM
Team JR/DFA, KBDD Team Captain
Ah Clem's Avatar
The foam around the wiring looks good, but make sure that you remove that strap around the BeastX before you fly it! (it will transmit vibration directly into the FBL unit, negating all the work you did to wrap the wires in foam).

Make sure that the bundled wires cannot flap loosely as the FBL unit can interpret that as movement of the helicopter.

Also, make sure that you tape or glue the wires into the FBL unit-I have seen those fall out on people in flight and it never ends well (it is very dangerous if they come out-mine are all taped in with the 3M gray tape under the foam).

"But from my point of view a device which needs these kind of trials and errors (different glues, combination of different glues, combination of different glues and metal plates, strap it down or no, wrap the wires with foam.........etc.) is useless. The user and installation manual do nor mention any of these tricks."

I can understand that, but in the dim dark past had the same problem with a V-Bar (tail drift due to high frequency vibration). I have worked with these things (FBL units for about 10 years now ,45 years in RC helicopters). Over time you tend to figure things out, learn from others who have dealt with issues before, etc. I do the same business with wrapping the wires in foam, etc. no matter what brand of FBL unit I am using and have not had a problem since I started doing so.

None of the manufacturers mention taping or gluing the wires into the FBL units either, but it is worth doing (people also use hot glue-I don't like this as it is a pain to remove, hence the double-sided foam tape).

Although it is possible that your particular BeastX is defective, they are, in general, an excellent FBL unit. I had a dozen in service for a while (I think I still have nine in service at the moment). The ones that were removed were the AR7200BX version, which is a combination BeastX and Spektrum receiver (and an excellent unit for Spektrum users). As I continue to migrate machines from Spektrum to JR DMSS, I no longer use them.

The first photo (below) is a photo of the FBL unit installation in the Tarot (now Steam) 550 I assembled last year.

The second is of the FBL unit in the Forza 700 I built recently. Same deal with the foam around the wires. On the Forza, there is foam on the inside of the canopy where it is over the boom cover, to make sure that the canopy cannot flap/tap against the FBL Unit.

The third photo shows the installation of the Mini-Blue V-Bar in my Forza 450. The V-Bar has since been replaced by a TAGS-Mini but the new installation still uses foam in the same manner.

The last photo is of the FBL mounting in the MD 6. Note that the wires going around the back of the FBL unit DO NOT TOUCH IT in any way.
Last edited by Ah Clem; Aug 03, 2021 at 11:14 PM.
Aug 22, 2021, 04:34 PM
Registered User
Thread OP
Thank you for all suggestions. But finally I decided to convert the heli back to FB.

I contacted the official support of xbeast. But they are not reponsive at all. I got only useless advices and questios then no answer for days or weeks.
They suggested to replace the tail servo according to them the tail servo is the root of the issue.
Before I tried out the heli with the modifications described above I replaced the servo for a new one.

The heli was stable at hoovering for approximately 2 minutes, then the tail started to oscillate with increasing amplitude. The oscillation reachead ~45 degrees in both directions until it started and uncontrollable rotation . It was a quite rapid process, took only a few sec.

The result is a crash again.
Later I noticed that the tail servo is dead.

It was enough from microbeast. It is a piece of sh..t with a sh..t customer support.
Sep 09, 2021, 01:36 PM
Team JR/DFA, KBDD Team Captain
Ah Clem's Avatar
ottist,

I understand.

I have had this sort of thing happen to me in the past-a piece of equipment that just does not behave the way I think it should.

Even if others were successful with the same unit-I declared it to be "bad" and gave up on it.

When I got a bit older, I started to wonder how some of those people could be successful with something I "knew" was no good.

I learned to slow down a bit and tried to learn what they were doing differently (sometimes it was something minor, sometimes something major).

Case in point was the old Trex 250-if I turned the rudder gyro gain up enough to get the tail to hold through maneuvers, I couldn't stop it from wagging. It had a flybar on it at the time, and a Futaba GY-520 gyro (an excellent gyro).

I decided to set it aside for a while (turned out to be around six month).

In the meantime, I was quite a few videos of people flying and enjoying their Trex 250's.

I started to wonder what they were doing differently.

Now some others had experienced tail wag, and some (not all) had cured it. People posted quite a bit of information regarding how to correct it (almost all of which I tried).

I re-built the tail three times until it was glassy smooth.
I put much better tail servo on it (a JR 3500G-which was gigantic for that small of a helicopter).
I installed KBDD Tail Blades on it
I changed to the latest version of Align Tail Blade grips (with a different bearing setup and Chinese Weights).
I changed the tail rotor input bellcrank to the laters version (which was metal and longer on the input side).

After all this, the tail behaved properly.

I realize that you had a drift issue-not the wag like my Trex did-different problem.

But there are people using the BeastX with excellent results out there.

If you want any assistance it is here.

By the way, I upgraded the Trex 250 to FBL later and used a BeastX for the FBL unit.
Oct 12, 2021, 07:00 AM
Registered User
Did you already the tail pushrod for no drift in non heading hold hovers? You do this before switching into HH. Also it's not the percent gain your looking for, the manual tells you what Letter should be highlighted on the unit to get you started which has always worked for me


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