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justjustin · 12-04-2015, 11:30 AM

Any one have any ideas.. trex 250 plus dfc
I can't get my tail gain in the tx right! It's on 26 in my dx7 and the tail just doesn't hold well enough in a hover.Any higher than that and i get violent wag on a pitch up! So not high enough for a solid tail and slight wag on pitch up but bearable. Have had nothing but issues with this 250 (several things) and this is just the latest.. So annoying..
I've done the extra tail holder bearings and am using ar7200bx and the kbdd tail blades. Have tried the parameter d at very low and the tail held well with 30% from the tx but had the wag on a pitch up.. Waiting for new landing skids and a servo arm at the moment
Any help would be appreciated..

myxiplx · 12-04-2015, 01:13 PM

For the 250 you need a combination of some careful tinkering on the mechanics, and a good FBL. You can get it flying well, but it does sometimes need some persistence.

On the mechanical side, you need it to be smooth, with a very fast tail servo. The best results tend to be with servos like the DS76t or DS95i with under 0.04s speeds.

On my Vortex after I tune the gain I end up adding a lot of collective to tail pre-comp, it really helps the tail hold in sudden moves.

Also, with lower headspeed you have less torque on the tail, do you know what headspeed you are running?

justjustin · 12-05-2015, 07:03 AM

Hi Thanks for the reply. I'm on 85% normal and 90% IU1 . The tail is the same in both..Running everything stock apart from bx and tail blades..
I shall have a look at changing the servo once I've eliminiated a few other things. Not had chance to fly again yet but have loosened the blade grip linkage arms a little even though there didn't feel as there was any binding and shal goo through the mechanical side again..

justjustin · 12-06-2015, 04:07 AM

So, the tail isn't binding at all. Would i be right in wondering to change the size of the tail blades up from 40mm and keeping the gain similar would keep the tail steady in hover, bigger blades better holding? ( forward flight is a bit out of the question at the moment)
What would be the possible cause of the gain being too high when putting the heli under stress yet not enough to keep the tail steady in a hover? Have the pitch slider centered on the tail shaft( i couldn't set the tail up in rate mode without it being only a few mm away from the tail case to hold without drift!)

12-04-2015, 11:30 AM	#1 (permalink)
justjustin Registered Users Join Date: Jul 2015	Gain to high in pitch up and too low to hold tail properly Any one have any ideas.. trex 250 plus dfc I can't get my tail gain in the tx right! It's on 26 in my dx7 and the tail just doesn't hold well enough in a hover.Any higher than that and i get violent wag on a pitch up! So not high enough for a solid tail and slight wag on pitch up but bearable. Have had nothing but issues with this 250 (several things) and this is just the latest.. So annoying.. I've done the extra tail holder bearings and am using ar7200bx and the kbdd tail blades. Have tried the parameter d at very low and the tail held well with 30% from the tx but had the wag on a pitch up.. Waiting for new landing skids and a servo arm at the moment Any help would be appreciated..

12-04-2015, 01:13 PM	#2 (permalink)
myxiplx Registered Users Join Date: Apr 2013	For the 250 you need a combination of some careful tinkering on the mechanics, and a good FBL. You can get it flying well, but it does sometimes need some persistence. On the mechanical side, you need it to be smooth, with a very fast tail servo. The best results tend to be with servos like the DS76t or DS95i with under 0.04s speeds. On my Vortex after I tune the gain I end up adding a lot of collective to tail pre-comp, it really helps the tail hold in sudden moves. Also, with lower headspeed you have less torque on the tail, do you know what headspeed you are running? __________________ Helis: Oxy 4 Max (day + night), Gaui X3 380, Oxy2 FE 215, Oxy2 Sport 190 Radio & FBL: Spartan Vortex, MSH Brain, Jeti DS-14, Spektrum DX8G2 Sims: RealFlight & AccuRC

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12-05-2015, 07:03 AM	#3 (permalink)
justjustin Registered Users Thread Starter Join Date: Jul 2015	Hi Thanks for the reply. I'm on 85% normal and 90% IU1 . The tail is the same in both..Running everything stock apart from bx and tail blades.. I shall have a look at changing the servo once I've eliminiated a few other things. Not had chance to fly again yet but have loosened the blade grip linkage arms a little even though there didn't feel as there was any binding and shal goo through the mechanical side again..

12-06-2015, 04:07 AM	#4 (permalink)
justjustin Registered Users Thread Starter Join Date: Jul 2015	So, the tail isn't binding at all. Would i be right in wondering to change the size of the tail blades up from 40mm and keeping the gain similar would keep the tail steady in hover, bigger blades better holding? ( forward flight is a bit out of the question at the moment) What would be the possible cause of the gain being too high when putting the heli under stress yet not enough to keep the tail steady in a hover? Have the pitch slider centered on the tail shaft( i couldn't set the tail up in rate mode without it being only a few mm away from the tail case to hold without drift!)

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