I believe, currently even the cheapest FBL controller (turnigy) costs 160+ USD. Price is the only down side Iam seeing. And big guys like mikado costs like 400 

beast x is pretty much like the old v-bar4.0 and play in a different liege compare to turnigy when it come to tail control  and works good on nitro as well

v bar 5,0 is extremly good on small machines but more money for sure, 400 is a old number, v5 mini is 299 now

hi anwar bhai
i need help soon! was hovering my 250 all these days with training gear on and the tail was holding great.but today after taking them off i noticed a minor twitch/wag in the tail! gyro is in HH mode with 15 gain now(previously 25). little skeptical to go below that...what do u think might be the problem?any suggestions....

Is the wag horizontal or vertical (looking from behind the heli) ? 

If it is vertical (a see-saw kind of rocking motion between the head and tail), the likely explanation is this... with the added weight of the training gear, you would need higher throttle to hover, and the more the head speed, the better the tail authority.  Now when you remove the training gears, you may be hovering at a lower throttle position, which means lesser head speed and lesser tail authority.  It is something to be fixed with an increase in throttle curve, and not with gyro gain.

If the wagging is horizontal and rapid, that is to be fixed with gyro gain.

Anwar, I saw his heli, He had built it very well. In fact the ball link on the tail servo was also near the center of the servo giving more resolution. Just wondering why such a low gain is required. I agree that once I came out of the training gear I had to reduce the gain on my heli, but a value of 15 is pathetic. Dunno, not much experienced here. 

The gain is whatever you end up with, with the heli "behaving".  Can't remember what gain settings we ended up with for Santhosh's 250.

The position of the ball link is on the servo arm affects the "limit" settings of the gyro.

With the training gear on, it may cause the heli to resist yaw correction, that is why a bigger gain may be needed when the training gear is on.  Think of it as the gyro having to twist a bigger mass into position.

Which radio are you using ?  If it is a JR/Spektrum, 15 is just fine (translates to 30 on Futaba), I run 25 on a Futaba (for Trex 600N with Logictech gyro), which would have translated to 12.5 on a JR (within a given mode... rate or HH) !

I tot the gain effects the ball link position and vice versa. since edger the ball, more the tail moves and hence lower gain is required, i remember reading this on other forum.   Not sure where i read or in which tutorial i saw

He is using some chinese radio. Though it was cheap, I felt the stick movement FEEL to be more superior to my RDS/A highend JR/Futaba that I have used. It had a kinda ball bearing feel. I felt it was perfect for flying Helis.   Unfortunately he is mode 1 and I couldnt feel his heli.  

I didn't put it down fully.  On any typical gyro, the way I decide where to put the ball link on the servo is decided by looking at how much is my "limit" settings at various ball link positions (and most heli manuals come with recommendations for what distance to use).  I want to get the limit settings close to 100 (between 80 and 100).  After that, the gain is whatever the gain I end up with.

And yes, the gain is affected by servo arm length.

Thanks anwar for the tip. 

If the radio supports software switching from mode 1 to mode 2 (and vice versa), then there is a way out.  I have to do this often when testing Prakkat's helis, as he flies mode 1.  I flip the radio to "mode 2" from "mode 1" in software, and ensure that the throttle is held down by force (this stick was elevator in mode 1, and has spring tension).  Similarly, I ensure that elevator is at the centre (it is originally the throttle, so it tends to stay where you keep).  Holding the sticks by force like this, I seek someone else's help in starting up the heli.  This allows me to test fly the helis on mode 1 radios with out having to rebind/reprogram it on another (mode 2) radio, or rig up some kind of buddy setup between the two radios.

Of course, I have to remember to switch the radio back to mode 1 in software when the testing is done.

hi guys sorry for the delay...going through a frustrating phase...after some good no. of hovers finally crashed the 250 yesterday....feathering shaft broke and the main shaft was bent...no other serious damages...luckily had the spares...but now the heli just refuses to fly the way it used to! the pitch mixing arms have some play...not sure if they did before the crash....play is causing about 1 deg deficit in the pitch each time i spool up.....so disassembled everything and tightened it back....slight vibration is still there...to make up for the slight deficit now, i hav increased the swash pitch mix from 50% to 55%...pitch is fine but now the tail is vibrating/rapid horizontal wags and am not able to figure out why! really miss having fellow fliers around...! would appreciate some help!

check this out.. specially the vids..
http://www.helifreak.com/showthread.php?t=107276





i eliminated my wag and used to get perfect piros and stops jsut by sanding the brass tubings...

hi sujju thank u for the reply...my tail was holding great before the crash....its not the binding problem...i guess it was coz of some loosened screws in the head causing lotta vibrations in turn causing the tail wag....well heli is kinda better now with minimal wag....will try to tweak around a bit more and see...

guys am just not able to eliminate the tail wag post crash.... tried evrything...theres no binding problem or belt prob....am frustrated my gain is as low as 10!!

what is your tail setup?
do u have vibrations?
small razor 1 is the worst
, have u tried to take off main blades and disconnect tail servo and spin up heli and feel the push rod if the tail is binding?

have u tried another tail servo or gyro?
what is the exact distance between center of screw and ball on the servo arm?

what rpm do u have? have u tried to run on 100% flat or lower?

have u tried bigger tail blades or smaller?

normally it is loads of play in the mixer arms( thats why everybody should run fbl ;o) ) but how is the blade tracking? is it out or does it go out of track and course vibes?

have u balansed the mains?

r you sure u did not bend the spindle in the tail in the crash?

well here is the checklist i've been through
new tail blade grips(SE)
tail belt -ok
new shaft
new feathering shaft
new smaller tail blades
gain range adjustment from as low as 5% to 50%
changed the main blades
changed the gyro pads
changed the tail servo
new tail push rod
belt tightness checked
adjusted the space between the motor pinion and the main gear
tail rotor shaft metal-new
no binding in the tail anywhere
push rod close to 5mm
tried lower head speed

and the wag continues
and not much of vibrations from the main rotors...
this is frustrating ...please help...its quite discouraging for a newbie...i also spooled the heli up without the main blades to full throttle and the tail is still/no wag...the moment the heli lifts up the wag starts....

Doc - Can you post a video of what you are seeing ?  Please do use a zoom camera (or try to show the issue from both close by and at a small bit of distance).

ok Anwar bhai will do that soon...
rgds

which hole on the servo of the tail servo have your placed the ball on?... try to be as close to the centre of the servo as possible..
rgds

hi anwar bhai...sorry coudnt shoot a vid of my heli i dont have a camera right now....well i've tried almost everything in the book to eliminate the wag but it just doesnt seem to stop..!i've almost given up!...can you pm me your contact no. if possible so that i can contact you directly regarding my issue...please help

I am out of India, so something like Skype may be better.  I will send you my details, although it does make every bit of sense to see what exactly is going on.  Since you are Bangalore, is it possible to borrow a cam from friends (or have them shoot some clips) ?  Even a better mobile phone would do.

ya anwar bhai il do that...!il try to get a cam...anyways plz PM me your details...thank you

anwar bhai thank you for your contact details...will get back to you with some videos of my rex...meanwhile can i increase the bec voltage to 6 volts...am running stock ds410 and jr290g servos...do think it might improve the tail?and does governer mode help in trex 250?should i try that setting?

one more thing anwarbhai how do i know if the motor bearings are damaged or something? when i disconnect the motor away from the main gear n try to spin it manually i feel its a little snugged!....