450 Trex 450 PRO DFC - 3GX Elevator Drifting Bad - Out of the BLUE!!! Any Suggestions ?

[Nl Henderson]

So I was flying the trex 450 pro (super combo) (no 3D) just some normal light sport flying, came down to land, kicked it in normal mode, got close to the ground and all of a sudden it was like I was giving it forward elevator. I did catch it and got it landed with no problems. I put a fresh battery it in, took off and put it in a hover, no issues at all, switched to IU1 and proceeded to do some fast forward and light sport flying. I then came in to land, switched to norm mode and about 2' off the ground it was like I just shoved the elevator forward $#&@%$%@ CRASH!!

I then proceeded with the rebuild: Tail Boom, Main gear, tail push rod, Main Shaft, tail boom supports, Main blades, stripped tail servo, stripped elevator servo,

I got it rebuilt, took off in to a hover, everything seems fine, switched to IU1, light sport flying, came down to land and low and behold , the heli is now drifting to the right like I am inputting right aileron .

Any Suggestions on how to fix this issue that keeps trying to put my heli in the graveyard????

I am running version 2.1 and am thinking of going to the 3.0. I have it downloaded but have not yet flashed the 3GX unit yet.

Thanks for Advice!!!

 

[Tony]

Re: Trex 450 PRO DFC - 3GX Elevator Drifting Bad - Out of the BLUE!!! Any Suggestio

Damn, there are a lot of mechanical failures resulting in crashes here lately.

I would go through all of the 3GX setup again and verify everything. Only thing I can think of is you have a gyro going bad. But that is unlikely.

 

[Westy]

Re: Trex 450 PRO DFC - 3GX Elevator Drifting Bad - Out of the BLUE!!! Any Suggestio

what TX are you using? Sorry to hear the crash news .... it always hurts when it is not a pilot error.

 

[Nl Henderson]

Re: Trex 450 PRO DFC - 3GX Elevator Drifting Bad - Out of the BLUE!!! Any Suggestio

I'm using the Futaba T8FG Super with the R6208SB RX. I have no issues on the trex 250 Pro DFC as of yet. I only have about 15 flights on the 450 and about 10 on the 250. So far I don't have a problem with the 3GX but I am starting to not trust it. I just flashed the firmware to version 3.0 and I am going to go through the full DIR set up and try it out in the morning.

Is the DIR settings all I need to go through, or do I need to redo the entire set up. (90 servos, level swash,end points, gyro???)

 

[Lee]

Re: Trex 450 PRO DFC - 3GX Elevator Drifting Bad - Out of the BLUE!!! Any Suggestio

When you do take it up again. Knowing that it does something weird when switching back to Norm mode, don't do it so close to the ground. Then if something looks out of sorts, you have time to switch it back. And you can land in IU if you want and use Throttle hold to cut the power. But thats not a solution, just an incase it happens again tip.

 

[Westy]

Re: Trex 450 PRO DFC - 3GX Elevator Drifting Bad - Out of the BLUE!!! Any Suggestio

The only time I have ever had an issue like that, it was a cyclic servo that was sending a back feed into the RX (Theoretically) as when I worked out which servo was doing it ..... I changed it out and problem gone!

All the servos were snapping to their extreme ranges at certain head speeds, So I think the harmonics were causing a loose or semi dry contact on the servo board to become compromised. I tested the servo for hours on a servo tester and it gave not one sign of an issue .... so to the bin it ended! I even stripped it down and inspected the internals and found no visible issue.

not sure if that is your issue though, but a thought well worth considering.

 

[Nl Henderson]

Re: Trex 450 PRO DFC - 3GX Elevator Drifting Bad - Out of the BLUE!!! Any Suggestio

Update Trex 450 Pro DFC: I flashed the 3GX to version 3.0 - I went back through the entire DIR set up and flight mode parameters. I reprogrammed the ESC to soft start with no GOV. The bird seems to be holding solid but with (2) issues.

1.) In IU2 when I pitch up hard the heli rolls to the left - how do I cure this??
2.) My ESC has the GOV turned off (red light) when I take off - But when I land the light has turned to green - how is this possible and how do I fix this????

Once again, Thanks for all the help

 

[Tony]

Re: Trex 450 PRO DFC - 3GX Elevator Drifting Bad - Out of the BLUE!!! Any Suggestio

#1, the only thing I can think of is you have a servo that is a little weak, or a little slow. I looked though all of the settings and I'm not seeing anyting for any kind of compensation for roll when adding collective.

You will have to forgive me, but I can not remember what Tx you are using so I will go through both the DX6i (6ch) and DX8 (8ch).

If you are running a DX7s or DX8, then you will use Channel 5 or the gear channel to adjust the GOV. YOu will have to remap the switch to do this. Your gyro will be on Channel 7 of the Tx. But, this is ONLY if you are running the satellite Rx's and not the standard Rx.

If you are running a DX6i and using the 6ch rx, then channel 5 is used for the gyro (as it normally is) and you can't use the GOV since there are not enough channels. The ONLY way you can turn it on and off at will is with a 7+CH Tx.

Again, forgive me for not remembering what Tx you have. I have NO idea why it would change in mid flight, but rest assured it shouldn't be adjusting any flight settings since you don't have a speed sensor for it to work.

 

[Westy]

Re: Trex 450 PRO DFC - 3GX Elevator Drifting Bad - Out of the BLUE!!! Any Suggestio

Update Trex 450 Pro DFC: I flashed the 3GX to version 3.0 - I went back through the entire DIR set up and flight mode parameters. I reprogrammed the ESC to soft start with no GOV. The bird seems to be holding solid but with (2) issues.

1.) In IU2 when I pitch up hard the heli rolls to the left - how do I cure this??
2.) My ESC has the GOV turned off (red light) when I take off - But when I land the light has turned to green - how is this possible and how do I fix this????

Once again, Thanks for all the help

Have you callibrated the Gov?.... 3GX still needs to know the bottom and top input values even if you are not using a governor.

It is easy to do ....

Power up TX and put throttle in low position
hold down setup menu and power up the RX.... hold till all the LED's stop scrolling and go solid..... release button and then move throttle from low to high position. the lights will then all flash and then the Gyro will go back into normal mode.

Are you seeing any vibes at all?

you could try swapping the servos around (for example, move each one clockwise one position .... so starting at the back, the elevator now becomes pitch, pitch moves to Aileron and aeleron moves to Elevator) and see if the roll moves in the same direction or stays the same?......

I know it takes a long time to change out servos .... but would be interesting if it follows a complete servo rotation ... then you can then pin point it down to one servo (or 2) causing the issue.

 

[Tony]

Re: Trex 450 PRO DFC - 3GX Elevator Drifting Bad - Out of the BLUE!!! Any Suggestio

Ah, yes. Thanks for adding that. It is a required setup.