Xxtreme Tail Issue / total write off crash

[MrMel]

Is there any common nominators between yours and Jamin_00's helis?, same shop built it or even same something (as you fly at the same field I mean, forgive me if I'm wrong, but two helis from same field with same problem strikes me as odd)

as I help ReadyHeli's support on Mikado, Kontronik and some other things (remotely from Sweden) I can for sure say no-one else has encountered a mushy tail or blowout or even tail issues and asked me about it.

I asked about some details from Jamin, which might help, but the drivetrain is firm, the vbar tail routine has a life-length of 7ms, meaning an error would happen right away if some settings was off, and I checked Jamin's settings, they are pretty much identical to mine, I mean EXACT, except for one thing, a hole difference on servo arm, that's it and since the servo is strong I doubt that's the cause.

My own XX with same settings except the limits are performing exceptionally.

I simply hate when I have a case like this myself, no argue there, they suck since I NEED to find a firm case.
But to help you I need more details.



/Fredrik

[Gareth-71]

Originally Posted by MrMel

Is there any common nominators between yours and Jamin_00's helis?, same shop built it or even same something (as you fly at the same field I mean, forgive me if I'm wrong, but two helis from same field with same problem strikes me as odd)

as I help ReadyHeli's support on Mikado, Kontronik and some other things (remotely from Sweden) I can for sure say no-one else has encountered a mushy tail or blowout or even tail issues and asked me about it.

I asked about some details from Jamin, which might help, but the drivetrain is firm, the vbar tail routine has a life-length of 7ms, meaning an error would happen right away if some settings was off, and I checked Jamin's settings, they are pretty much identical to mine, I mean EXACT, except for one thing, a hole difference on servo arm, that's it and since the servo is strong I doubt that's the cause.

My own XX with same settings except the limits are performing exceptionally.

I simply hate when I have a case like this myself, no argue there, they suck since I NEED to find a firm case.
But to help you I need more details.



/Fredrik

Thanks for the great post!

Yes, Jarmin built both ( well we did both together but he did 99% ).
We share an office at work, and spend more time than we should building helis etc.

I have spent a lot of time helping him with his tail issue and we are getting no where. this is what is making think that finding a resolution might be hard.

After my crash jarmin again went though his heli with a tooth comb and all as exacly as in build manual.

FYI, I changed the tail servo hole on jarmin's heli as part of the testing / fault finding problem. We have also run his at 5.2 and 6v all the same. It is confusing.....

We are also running identical gear, although he has futaba servos and I have outrage servos ( both running outrage tail servos ). I have a few of the servos as we tried swapping them out, to no avail. In addition he is spectrum and I am futaba.

So the common parts really are the tail servo and bec.

Gareth

[MrMel]

I asked for some pictures from Jarmin, let's start there, break it down simplest component.
I still think best bet is something overloading (physically) the tail servo, which means from the pushrod and back, its not that many components, so I would go over each one.


This is not a recommendation from Mikado nor Readyheli, make clear on this, do NOT try this if you do not know what your doing..
but personally, what I would do (on Jarmins), is to unhook the servo arm, spin up the heli at mid RPM (like 1400 on the XX) without mainblades but with tailblades, then move the tail pushrod by hand, KNOW THIS ITS EXTREMELY POWERFUL, but it gives me a sense if its hard or not to move, tailservos are not strong at all.

[jtjohn1]

Noob thought here (I R NOOB HEAR ME ROAR!!)

If you have a BLS157 handy that you could put on the tail to see if that helps (It's so strong that I would think it would push thru most sticky issues better than a normal tail servo would)

That said I am not sure how bad an idea is it to use a 157 as a tail servo (Even for testing purposes)

[DannyvG]

how is the power consumption of those outrage servos on 5.6V in a 800size heli? And what is the input voltage of the bec, you where using a Herc Super Bec right?
I wouldnt be surprised if the cause of these problems can be found in that direction.
But without event log or further investigation, who knows...

average amperage of my friends xxtreme is in the 3.6A range for futaba bls157 on direct 2S lipo.
So on 5.6V you would theoretically already use 5.2A on average with very efficient servos. So who knows what the spikes will do. and how different components react to those voltage dips that might occur.

[Gareth-71]

Originally Posted by djamgils

how is the power consumption of those outrage servos on 5.6V in a 800size heli? And what is the input voltage of the bec, you where using a Herc Super Bec right?
I wouldnt be surprised if the cause of these problems can be found in that direction.
But without event log or further investigation, who knows...

average amperage of my friends xxtreme is in the 3.6A range for futaba bls157 on direct 2S lipo.
So on 5.6V you would theoretically already use 5.2A on average with very efficient servos. So who knows what the spikes will do. and how different components react to those voltage dips that might occur.

Hi

My xXtreme was running at the high voltage ( 8v I think ) as it does on most of my other helis.

Gareth

[MrMel]

as I have seen Jamin_00's log I can say for sure that one does not suffer from low voltage issue, and if it would, it would be from start, it's nothing that "builds up during flight"

I cant help it but the mushy tail I think is key (mainly since I have not heard anyone else with this, so it might be unique to this case)

I would try this as well;
Take off main blades
spool up the heli on the ground and control the tail forth and back for a minute.
Then measure/check temp of the servo.

Try one hole further in and do the same exercise.

[DannyvG]

Originally Posted by MrMel

as I have seen Jamin_00's log I can say for sure that one does not suffer from low voltage issue, and if it would, it would be from start, it's nothing that "builds up during flight"

Bec overheating is a building up process I would think.
But ok, if jamins log doesnt show that then with him it isnt the problem. Unless like you said the servo would become to weak even though the rest still gets enough power supplied. Dont know if thats a plausible thing.

[MrMel]

If the servo becomes hot enough, yes, then its plausible that it can start to slow down/lock up without the rest of the system knows about it.
( I have a computer based servo tester where I test some servos until death, and it goes down that way)

[Mercuriell]

I had a similar problem with the Diabolo, that was caused by an incorrect assembly order of bearings in the initial manufacturer instructions. The key here was that the radial bearings were notchy as they were being subjected to axial loads - Gareth/Ben any evidence of notchiness in your tail radials?

I cant see it being a tail servo issue, my next thought would be the vbar sensor, hook it up to a pc and look at the gyro input on the opening page, give the sensor a light tap and look for any loss of signal, evidence of that should also be in the logs.

BTW gents, cut the personal comments out, they dont help the problem and are against the HF ethos of respect. Sorry for your traumas Gareth, nothing worse that NOT knowing WTF went wrong.

[Gareth-71]

Hi All

Well, now we know with relative certainty what went wrong ...

The log is full of "High Vibration" then "Extreme Vibration" and also lots of checksum errors, low voltage errorss and loss of connection errors.

It turns out that all of these errors can be replicated simply by removing the vbar sensor wire.

So, in 1000's of hours of flying and crashing a lot of helis I have never once had any servo / sensor / rx wire fall out. It just had to be on my most expensive and newest heli!

To those that took offence to my posts, I did make it clear that I was not blaming anything until I knew what the fault was - Now I KNOW - it was the fault of the vbar - why should the heli go out of control just because a sensor lead fell out? ;-) [just kidding ok!]

What still confuses me though, is that when I hit hold, I got control back and when I put the power back on, it was the tail only that I struggled to control / was out of control...

Hmmn!

Thank you to those that have contributed to trying to resolve this issue.

Gareth

[MrMel]

What still confuses me though, is that when I hit hold, I got control back and when I put the power back on, it was the tail only that I struggled to control / was out of control...

Ahhhhh

Yes, I know EXACTLY what you mean now!
Been there done that, but with another flavor, I flew with my android phone in the pocket in SETUP mode = same thing, NO GYRO.

The tail becomes HYPER sensitive, touch it and wow 180 degree in one direction, sneeze and 180 degree in other.

In the end I hit throttle hold and crashed it "nicely"

I wonder how they did it back in the 80s with no gyros !??!?

[Nko15]

Originally Posted by MrMel

I wonder how they did it back in the 80s with no gyros !??!?

the only had servos with a travel speed of a week/60 degrees..

[DannyvG]

Originally Posted by Gareth-71

The log is full of "High Vibration" then "Extreme Vibration" and also lots of checksum errors, low voltage errorss and loss of connection errors.

It turns out that all of these errors can be replicated simply by removing the vbar sensor wire.

So, in 1000's of hours of flying and crashing a lot of helis I have never once had any servo / sensor / rx wire fall out. It just had to be on my most expensive and newest heli!

So you didnt use any hotglue or something similar on the connectors? Then I am suprised it never happened before.

What I dont understand is how a loose sensor connector can cause low voltage warnings?
Care to post the entire log please, would be interesting to see.

[helicraze]

Sometimes in a crash it does not always happen as you remember. Things happen so fast and most people try to blame all but themselves

Build it again and keep flying.

Unfortunately if you dont know you dont know. I constantly learn about helis. Often try to suggest to others at the club when their sats are on carbon etc sometimes they look at me puzzled and say well i never had an issue. Oh well we all learn

[MrMel]

What I dont understand is how a loose sensor connector can cause low voltage warnings?

Intermittent connection to the sensor will cause the 3.3v to fluctuate, and the low voltage warning on that is VERY sensitive/correct so it will warm right away.

[Gareth-71]

Originally Posted by djamgils

So you didnt use any hotglue or something similar on the connectors? Then I am suprised it never happened before.

What I dont understand is how a loose sensor connector can cause low voltage warnings?
Care to post the entire log please, would be interesting to see.

Hi

I did for a while, I used Zap-a-Dappa-Goo II until I returned a faulty vbar to Mikado and they made unhappy comments about it so I no longer use it.

Also, please show me where it says in any instruction / installation guide for anything that the plugs should have a secondary method of retention.....

[DannyvG]

Originally Posted by Gareth-71

Also, please show me where it says in any instruction / installation guide for anything that the plugs should have a secondary method of retention.....

Page 18 of the Compass 7HV manual for example

Secure connectors with heat glue at the receiver and
FBL-Unit. Avoid contact of the glue with stickers and

the wires. The glue is easy to remove.

http://www.mttec.de/download/Manual/...l_2_042012.pdf
Besides that it is pretty common knowledge to use hot glue to secure connectors

In case you dont know, this is a hot glue gun
http://www.howardelectronics.com/ste.../WGF-3002L.jpg

[JamesGreen]

Originally Posted by djamgils

Page 18 of the Compass 7HV manual for example

http://www.mttec.de/download/Manual/...l_2_042012.pdf
Besides that it is pretty common knowledge to use hot glue to secure connectors

In case you dont know, this is a hot glue gun
http://www.howardelectronics.com/ste.../WGF-3002L.jpg

Thought we were talking about the xxtreme, what's the 7HV got to do with anything?

Just remember mate no one likes a smart arse. (or in your case someone trying to be one)



I think mikado should include something to retain the plugs. I have never used hot glue on my Heli's.

[DannyvG]

Originally Posted by Gareth-71

Also, please show me where it says in any instruction / installation guide for anything that the plugs should have a secondary method of retention.....

dont have to say more.