Ran out of rudder trim

[Wilfred]

I have just finished my T-rex 450 se and am having a few problems in an unstable hover. I guess I should mention at this point what you all suspect, I am fairly new to helicopters. I set the tail rotor up as per instruction manual and "Finless Bob's video so that in non-heading hold mode, the slider is in the center and the throw just reaches the bushings at each end. In hover, the nose twisted right with a small amount of wiggle from the gyro. I fed in all the left trim I had, but it is still not enough, and I have to hold a bit of left rudder stick. I thought about moving the servo arm to compensate for the trim, but I am not sure this is the best route to take. Any advice would be greatly appreciated, and may save my heli. If you need extra info I can add it to a later response

Thanks

Wilfred

[Skarn]

Hey bro,

You don't want to use any rudder trim with a HH gyro. Subtrim to get the servo arm at 90 is ok. If you use trim while in HH mode, when you initialize the gyro it will set that position as the new 0 position and ignore it.

From your post, I'm wondering if you are flying it in HH mode? It sounds like you might actually be flying it in rate mode.

How is your belt holding? Not too tight and binding is it? What settings do you have on your gyro? Are you using the gyro sense menu or gear ATVs?

Skarn

[LAMAR COOLEY]

Wilfred,
I assume you are talking about the Fut. 401.
Here is a couple of things to check and be aware of .
First remove the trim, go back to "0".
Then assure that you are initializing ( powering on) in "Heading Hold". Your gyro led should be on and glowing brightly(not blinking). If it's blinking you have powered up in "normal".
If I recall correctly, the 401 requires power-up in H.H.
It may be that you haven't set enough gain in H.H. and or Normal
Check your gain settings. The "normal" gain setting chould be anywhere from 1 to 49 or 50 and the "heading hold" chould be anywhere from 51 to 100.
Depending on the radio in use one of these values may have to be in the (- number range)
in order for the switch to distinguish which mode you are in . And the switch positon you prefer for toggling from one to the other.
Start out with 40 to 45 in "normal" and 65 to 70 in H.H.
Once you have powered up in H.H. Try flipping your gyro mode switch 3 times in rapid succession from H.H. to Normal and back.
If you have a little wag in H.H. Then bring your H.H. gain setting down a few numbers at a time until the wag goes away.
It might also help to re-review Mr. "Finless's" video.:noteworthy
By the way what radio are you useing ?
Hope this might get you sorted out.
Regards:cheers

[Wilfred]

Thanks guys for your quick responses. I apologize for taking "sooooo" long to get back to you. I just finished installing a wireless network in the house and messed it up as well.

Sorry, I should have included the equipment. I am using a Futaba T6EX transmitter and reciever with Spectrum SPMS75 servos on the swash and a Hitec HS-81 on the tail. The gyro is a Telebee Head lock & standard (dual rate) with the internal gain set at 100%.

The gain line for the gyro is on channel 5 with the gains in the gyro menu set as follows: Normal mode 40% and HH mode at 80%.

After reading your replies, I went back to the heli and inspected it again. Here is what I found. The tail rotor belt was very loose. The servo was extremely slow when I used full deflection on the rudder stick, and I was not getting full movement at the tail rotor slider.

I tightened the belt and took the tail push rod out of the center support hook. It is now straight and moves at normal speed now. I increased the End points on the rudder and am now waiting for the rain and wind to stop to retest.

I will keep you posted on the test flight reults. Thanks again for your timely advice.

Wilfred