General 250 DFC 3GX Tail Blowout

[scottwells]

Hey guys,

First thanks to everyone that helped me get the bird this far...

I have a very stable hover with the occasional tail kick to the right ( real quick) and then nothing for a couple of minutes.

When I try to pitch pump the tail kicks to the right pretty hard and then back to normal. I have been playing with my gains and I know that 50 on the radio is no good. I currently have it at 38% but I have gone as low as 25% (wags in hover), nothing seems to get rid of it completely.

Settings on the 3GX are: (from my computer)

Rudder Delay = 9

Rudder gain = 21

Rudder Locking Gain = 85

CP Torque Comp = 50

Anti- Torque Comp = 20

Gyro Settings on Dx7s are :

Ch = Aux 2

SW = Gyro

0 = 38.5

3GX Ports are at about 10:30 position

I havnt set anything for pos 1 or 2 because I cant get it to lock in on pos 0. I have tried higher head speed by switching to stunt mode 90% flat.

Once again hovers pretty stable, if I do nothing but hover it eventually kicks slightly but not bad. (after about 1.5 mins of hovering) When I try to pitch pump it kicks hard to the right and then back to straight. I have tried adjusting the gain value in the radio (i checked and it is adjusting on the software when I hook it up) and if I go to 50% i get wag in hover, if go below 30% it seems like I get wag in hover.......

When i get better I dont plan on hovering whole batteries but I am at a NOOBIE level and hovering and slow circuits is all I have tried so far, except a little pitch pump. If someone could just gt me in the right direction of what I should be trying to adjust that would be great, I will keep playing to dial it in but I am starting to think I am not doing something right or I have a parameter off somewhere.

Thank you.

Scott

 

[xokia]

I had a similar issues with my trex 250 hated the thing. There are a couple videos that explain the problems with the 250 tail. You can do the upgrades to make your tail better. My understanding is that the mks95 servo also solves the problem. I however didn't have the patience nor did I want to spend the money on an expensive tail servo. There are some other heli sites that have tons of information on this 250 and its problems. Good luck.

TREX 250 TAIL BLADE GRIP UPGRADE & CHINESE WEIGHT PART 1 - YouTube

TREX 250 TAIL BLADE GRIP UPGRADE & CHINESE WEIGHT PART 2 - YouTube

 

[scottwells]

Thanks xokia,

I have since set my delay to 0 and upped my pos 0 = 42% this seems to have helped but I have only tested it hovering in my front yard. I am going to try and get it to a field today or tomorrow and see how it holds in flight. Anyone who has other ideas please let me know.

I am really leaning towards getting the DS95i servo and and Ikon system. I just cant afford both right now, I might start with the servo and see how it changes things. A better servo cant hurt any. I have talked to people with the Ikon and they say that is the way to go but yet there people that swear by the 3GX. Being so new to heli's I dont know but the general consensus is upgrade the tail servo.....

Scott

 

[xokia]

The 3GX would be at the bottom of my list as far as FBL controllers go. There are just so many better options. But in this particular case I would go with the servo upgrade. I tried a BX on my 250 which didn't help squat on the tail. This problem isn't a FBL controller problem. Its a crappy tail design problem and you need a high torque tail servo to compensate for the bad design.

 

[Tony]

If you have a linear throttle curve, the tail is going to kick out on pitch pumps. You can only truly test this in IU with a flat throttle curve.

 

[scottwells]

Thanks guys,

I will try it with a flat curve, In my linear curve i have it where there is almost no kick, (some but real small).

I have only switched to my 90% flat curve once, I didnt try any pitch pumps, It was a little intimidating and I was only in my front yard. I will give it a shot when I get to a field where there is a little room for error. I think it is pretty good now for taking off and landing. I feel I am many batteries from trying even a simple flip or roll. (It is so easy on the sim but I dont seem to have the confidence with the real thing yet).

Like always I really appreciate all the great information.

Scott

- - - Updated - - -

Final Update

For anyone having similar issues reading this.

In idle up 0 I have found my gyro setting on the radio to be 35.5% seems to be a sweet spot. Stable for take off and landing every now and then a little kick to the right but nothing that freaks me out and I have only been flying since Dec 2013.