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HomeAircraftHelicopterFlybarless Rotor Head SystemsAlign 3G › T-Rex 250 Pro DCF w/ 3GX, what to do?
11-14-2014 04:21 PM  3 years agoPost 1
gmcullan

rrKey Veteran

Southbridge, MA

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I recently bought two Align T-Rex 250 Pro DCF helis. One came with V4.0 and the other V3.1.

From what I've been reading, the V4.0 shouldn't fly worth a darn. But it does so very well. At least in regard to my "Old Fart" flying style. The only issue is an occasional very mild twitch to the tail. It is currently bonded to a DSMX satellite.

The big issue is the V3.1 unit. Also using a satellite, it would only bond in DSM2 mode. And while the cyclic response is good, the tail has a violent side to side wag. This wag is regardless of gain and HH or Rate mode.

I've been through the setup of the V3.1 three times now. I'm confident that it is properly set up.

My guess is that my best (and possibly only) recourse is to upgrade the firmware to at least V4.0 and redo the setup?

I know there have been some very long threads in regard to the 3GX, and I have read through quite a bit of them. I'm just trying to "cut to the chase" here and get some quick thoughts.

Thank you for your input, and with best regards, Gerry Cullan,

Gerry Cullan,
Gaui 200, 255; T-Rex 250, 450 SE & SA, Mini-Titan, Blade 450

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11-15-2014 01:55 AM  3 years agoPost 2
dkshema

rrMaster

Cedar Rapids, IA

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Cut to the chase. Upgrade to V5.0. Put your gyro in RATE/NORMAL mode.

Hover the helicopter. Adjust the tail rotor linkage till you can hover with no tendency for the nose of the heli to yaw left or right. Recheck/re-set your left/right travel limits, go have fun.

What you read about V4.0 isn't quite right. V4.0 wasn't horrible, it just acted weird for many with respect to the tail gyro, while for others, it was just fine. V5.0, set up as described above works quite well. I've flown V5.0 in all my helis, nitro or electric, 250 up to 700 size, all have had no bad habits. My same stuff on V4.0 was just unhappy.

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V3.1 should be well-behaved no matter what heli you fly it on, and you simply center the pitch slider at neutral, set your endpoints and go fly.

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ANY version PRIOR to V4.0 does NOT directly support DSMx. A DSMx satellite will work fine with stuff PRIOR to V4.0, it will just bind and operate in DSM2 mode.

V4.0 introduced DSMx support which continues into V5.0. To BIND a DSMx satellite with V4.0/V5.0, in DSMx mode, requires that you hold hold the button on top of the 3GX down as you apply power to the unit with the binding plug installed. Release the button after you apply power. Of course, your transmitter needs to support DSMx protocol as well.

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You don't say WHICH transmitter you are using, but when using SATELLITE receivers with the 3GX, your transmitter MUST use CHANNEL 7 -- AUX 2 -- for rudder gyro gain control. That means if you own a JR transmitter, your gyro will be properly controlled when you enable the Gyro Sense menu. JR radios default to using Channel 7 as the Gyro gain control channel.

If you use a SPEKTRUM transmitter, you MUST reassign GYRO control to use CHANNEL 7, as the Spektrum default for gyro control is Channel 5. This may be the reason your tail rotor didn't behave well in your V3.1 units.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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11-15-2014 02:56 AM  3 years agoPost 3
gmcullan

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Southbridge, MA

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Dave, thank you for your response. The instructions for these controllers leaves something to be desired. That's were experience such as yours becomes invaluable.

I use a Spektrum DX7s transmitter. Regarding the v4.0 unit, binding was completed in DSMX mode without holding down the set button while powering up the 3GX/satellite combo. Gyro HH/Rate switching is off of my gear/gyro switch. Gyro appears to be channel 5. Tail response from this combo is nominal, and I can readily switch between HH and Rate mode.

The mechanical setup between the V3.1 and V4.0 based helis is similar. So are the 3GX settings with the exception that the satellite on the V3.1 unit is a DSMX unit bound and operating in DXM2 mode. I would normally do the final tail setup in rate mode so as to ensure a good mechanical setup. To me, this step is "old school" and every bit as valid now as it ever was. As with the V4.0 unit, my gear/gyro switch allows the selection of gyro HH/Rate Mode. I presume this is still channel 5.

Based on your comments and suggestions, I will undertake the following actions:

1. I will upgrade both units to V5.0 and run through all setup procedures again.

2. I will double check and confirm the channel assignment and gyro HH/Rate function.

Thank you for your help and guidance with these units. I currently fly (2) BeastX, (8) Spektrum AR7200BX, and (2) 3G units. So while I am not inexperienced with FBL controllers, the 3GX units are a new experience for me.

Thank you for your guidance, and with best regards,

Gerry Cullan

Gerry Cullan,
Gaui 200, 255; T-Rex 250, 450 SE & SA, Mini-Titan, Blade 450

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11-15-2014 03:20 AM  3 years agoPost 4
gmcullan

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Southbridge, MA

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OK, both units have been updated to V5.0. I have also checked and confirmed that both model settings in the DX7s gyro functions are set for Channel 7/Aux 2.

I will rebind both units tomorrow with the goal of getting both units set to DSMX, double check the setup settings, and hopefully at least test hover in the house.

Thanks again for your help. I'll let you know how it all works out.

Gerry Cullan,
Gaui 200, 255; T-Rex 250, 450 SE & SA, Mini-Titan, Blade 450

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11-15-2014 05:13 AM  3 years agoPost 5
dkshema

rrMaster

Cedar Rapids, IA

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Good deal making sure the gyro gain comes out of channel 7. With satellites that is the only option.

Keep in mind that going DSMx buys you nothing extra.

Monster tail wag that seemingly isn't affected by gyro settings says you have a mechanical problem.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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11-15-2014 01:17 PM  3 years agoPost 6
gmcullan

rrKey Veteran

Southbridge, MA

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Agreed on the mechanical problem. I have confirmed that the tail slider is free and smooth and that the ball links on both ends are also free and smooth. With no apparent mechanical binding, I'll swap in a different tail servo if the wag still exists. I have to head to work shortly (at the LHS), so I won't be able to test hover the two helis until this evening.

Thanks again for your help, Gerry Cullan

Gerry Cullan,
Gaui 200, 255; T-Rex 250, 450 SE & SA, Mini-Titan, Blade 450

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11-16-2014 06:54 AM  3 years agoPost 7
knightofcarnage

rrElite Veteran

chicago

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If all else fails
get a mks dsi95 and upgrade your 3gx to 3G Pro. My 250dfc now is flawless.

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11-16-2014 09:18 AM  3 years agoPost 8
coolice

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Northamptonshire, England

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Hey buddy.

With the tail wag, what are the rudder locking gain sliders set to within the software?
If these models were purchased secondhand, you may find one followed online advice with a reduced locking gain value and the other didn't.
.

Ian Contessa
Team Robbe SchluterUK
Midland Helicopters

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11-16-2014 04:07 PM  3 years agoPost 9
gmcullan

rrKey Veteran

Southbridge, MA

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Both units were upgraded to V5.0. The tail wag experienced with the original V3.1 unit is now gone.

While spooling up the V3.1 upgraded to V5.0 last evening to lift into a hover, the head seemed to explode. As the heli was barely inches into the air, it settled (fell!) down with no additional damage. Apparently, the spindle (feathering) shaft failed on one end by fracturing at the bottom of the threaded end where the blade grip bolt threads in. The blades and grips were recovered with the majority of the spindle retained in on grip and the fractured end in the other.

In all my years of flying rotary wing aircraft dating back to the mid 70s, I've never had such a failure. Other than the failed spindle, the only other damage was a broken DCF link.

Ah, the joys and challenges of rotary wing flight!

Gerry Cullan,
Gaui 200, 255; T-Rex 250, 450 SE & SA, Mini-Titan, Blade 450

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11-16-2014 06:51 PM  3 years agoPost 10
dkshema

rrMaster

Cedar Rapids, IA

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Many years ago, I had the rotor head on a Schluter HeliBoy break in flight. Way high up and not a pretty sight after it hit the ground.

A few years ago, when bailing out of a bad auto, one of my spindle bolts backed out and sent the blades flying. Again, not a pretty sight.

Helis just don't fly well when the rotor blades decide to part company.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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11-16-2014 10:10 PM  3 years agoPost 11
gmcullan

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Southbridge, MA

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Dave, you bring back some memories. My first heli was a Schluter Heli-Baby followed by a Heli-Boy.

Gerry Cullan,
Gaui 200, 255; T-Rex 250, 450 SE & SA, Mini-Titan, Blade 450

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