Flymentor Went Nuts

[Jamesb463]

Quote:
Originally Posted by helihaven View Post
I had a flymentor...once.....had a similar issue to the one you describe...the aileron servo would just twitch for 2 seconds...all on its on...with no input from transmitter whatsoever...verified this on the ground...happened every 22 seconds..i timed it, it would slam all the way up and just hold there....flymentor came off...problem went away..never happened again, still have it in my junk drawer somewhere.

My flymentor went nuts on me just after take off. Hovering 3-4 ft when heli twitched then twitched again then loss of stick control then Wham into the ground. Now I cant trust it and its no more.

Simply put I'll be going FBL on this heli too.

[pril250]

Did you consider that your ESC/BEC may have been rated too low to drive FM. This often happens as the minimum requirement needed is a continuous 5A for the supply to be deemed reliable.

From your description it appears as if you had a brownout.

I have used the same FM units on two helis including a 600 for years with no issue.

Admittedly once in a while a bad unit will leave the factory. Yes agreed this is a cheap replica of a more expensive marque but it is not that bad and certainly does a job of work.

[Jamesb463]

Thats complete news to me 5A?!

Where in the manual does it say that?

I did have a 3A separate BEC on my Trex450 pro and I thought that would've been sufficient.

I must stress that I have not seen any instruction in KDS literature recommending 5A for reliable operation.

This is my point about cheap knockedoff gear- Bad manuals , no firmware support, no comeback through faults, etc.
From now on I'll get the best or do without, Its as simple as that.

End of story.

[pril250]

I mostly agree with your post. Those things are not in the manual and are subject to what servos and other electronics are uses etc'. I found that out through trial and error thankfully not fatal errors. The thing is that FM is there to assist the novice in their first flight steps but requires the knowledge of a experienced pilot to understand, install and setup. That is where forums are helpful I guess, covering up for the manufactures shortcomings.

[Jamesb463]

unfortunately I cant afford a helicommand so I'm having another go with the flymentor.

How I hate having to do it considering my previous scathing remarks but I have to admit when it was working it was a great aid AND good fun!.

Maybe I'll have better luck this time.

I have a separate Hobbywing 3A/6v UBEC. will this be ok on a Trex 450 Pro- all standard electrics.( ESC supply is disconnected)

Many thanks.

[pril250]

What cyclic and tail servos are you using, 3A may be ok but 5A is better.

To test it initially, once it is all together, hold the heli in one hand and move it about in all orientations while wiggling the cyclic on the tx and see whether power is not lost and check if the UBEC remains cool. All this of course with the motor disconnected.

This is not a definitive test but will give you an idea of the behaviour of the electronics.

[Jamesb463]

Cyclic servos are Align DS410M.

Tail Servo is Align DS520.

I had FM installed before but something happened when hovering 3-4ft, twitched then no stick control then into the ground. It turned out that aDS415M servo was bad. Now I dont know whether FM caused it, or the 3A BEC, or whether the servo just went faulty. It was only 15 flights old and the other servos are ok. This was why I became distrusting of FM. But I am giving it another go as it was good when it worked.

Maybe get an 8A BEC and be done with it?!?!

[pril250]

All I can say is that it is very unlikely that FM could damage a servo but a blown servo can pull down the whole of the electronics. No familiar with those servos spec and whether they are 4.8v or 6v and what voltage was the BEC.

[Jamesb463]

servos are 4.8v or 6v, BEC was set to 6v.

[Jamesb463]

servos are 4.8 - 6v, BEC was set to 6v.

sorry duplicated this reply.

[Ivor Hill]

All my heli's including 500 size run on Hobbywing ESC with 3 amp bec set to 5v, but I use non digital cyclic servo's and digital on the tail. Digital servo's consume more power but 5 amp's is plenty, 8 amp is an overkill.
I have a number of Flymentor's and have never had a problem but if you think it was responsable for you crash wnen you get it working again tie the heli down so that it cannot fly to test it.
Keep the ESC to RX wire as far away from the other wires as possible.
Also bear in mind FM does not like exessive vibration and if subjected to it it is likley to crash the heli, the heli will normaly roll right and move backwards. The tie down test would show this.

[pril250]

It is the ESC's with the incorporated 2A BECs that are the most vulnerable because of the low rating and the combined temps generated. The 3A offers better chances but as mentioned no real overhead for digital servo use. The 5A in my opinion is the safe way to go. 8A as mentioned is an overkill.