MX400 Gyro problem

[Curtis Burns]

Hey guy's, been a while:

I bought a MX400 and put a GY401 on it and have no control over the tail. I just goes crazy. It calls for the 240 gyro I think but I just pulled off a 401 from my backup raptor 50 so I know the gyro works. I've tried everything including changing the gain and delay. Anyone had the same problem with the 401 and small electric heli's

Curt

[lakespinner2]

Is it just major wagging or total loss of tail control ? and which tail servo are u using ?

someone had a new mx400 at the field this weekend and it had a 401 gyro on it. After several tweaks the tail got better but it was still wagging a lot. the whole tail slider/llinkage was pretty stiff on his, I think his would benefit from taking the tail apart and making it smooth as silk. The tail blade grip balls were plastic and I think there may have been some mold flashing binding in the links.

[Curtis Burns]

It starts out wagging 30 to 60 degrees then 90 to 180 degrees then goes to no control as I apply collective. I may try to move the gyro up to the back where the gyros are on the rest of my machines. Im pretty sure the linkage is smooth but I'll recheck today.

Curt

[lakespinner2]

Wow, that is a loose tail. :!: I don't think the one I saw this weekend was quite that bad. It did take several attempts to get it to barely hover and then it wasn't pretty. I went thru similar tail wag woes on my original t-rexes. The tail on the mx400 remined me of the original t-rex tail design.

As I recall the best 'fixes' was to move the tail servo ball to the innermost hole on the horn (around 5 mm from the screw), and then max out the limit adjustment on the 401 as much as possible. At the time I was using the 401 with HS-56 servos. I suspect an inner hole might work well with most of these tiny servos.

Maybe I'll get a chance to see the mx400 again over the weekend. It'll be interesting to see if there's any improvement. good luck.

[929pilot]

Get your 401 as far from your speed control as possible because it picks up RF noise, and get your linkage as smooth as possible. I had the same problem on my T-rex.

[Curtis Burns]

I was told that I need my non-normal flight mode set so the throttle curve should be 100-100-100-100-100 which seems very high at mid-stick.

Anyone want to share their throttle curves?

Curt

[929pilot]

Most people use 100-100-100-100-100 in idle up 2. You may want to try 100-95-85-95-100 in idle 1 and 100-100-100-100-100 in idle up 2 and see if it works for your particular setup and flying style. Speed controls are most effecient at 100% and if you have the right pinion and motor combo overspeeding won't be a problem.

[Curtis Burns]

I bought the heli-max inrunner brushless and speed control the box suggested.
The pinion is stock also.

Curt

[lakespinner2]

The fellow at our local field had his new mx400 out again this past weekend. He had installed the t-rex XL tail assembly on it and the tail was rock solid. He still had very little power. Then he changed the CC25 ESC from governor mode to normal throttle curves and it turned into a screaming rocket. It had lots of power. He has some kind of little silver outrunner motor on it. I loaned him a 4 cell thunder power 2000 mah pro lite battery to use and it loved it. I didn't fly it but it looked to have tons of power. I tached it at 2800 rpm and it could probably go higher. It flipped and rolled with ease. It looks to be a great little machine.

[Hotshot Charlie]

Hey lakespinner,

Please find out more details on his setup, motor he is using, etc.

I have a X400 on the bench, starting build tonight or tomorrow.

Thanks, Rob

[lakespinner2]

Hi Rob,
I just got an email from the mx400 owner and he said the motor he's using is the Ultrafly C/13/28H. I know nothing about this motor except that it looks small compared to all my t-rex motors. It's an outrunner and he flew it maybe 5 or 6 minutes on my battery and when I recharged it he had used about 3/4 of the full charge. I'm guessing it would run 8 to 10 minutes or so with the 4 cell 2000 mah pro lite battery. The motor wasn't hot. I'm not even sure it was warm. We checked the battery temp and I believe it was around 108 or 109, not bad at all.

He has hs-55's I believe, and the gy-401 and the cc25 ESC. That's about all I can remember. This was just his second flying day with it and he just put in some rough curves so I'm sure it needs some fine tuning but it looked pretty impressive to me.

It will be interesting to see how it comes along, there aren't that many small electric helis around here so I'm always excited to see something new. Keep us posted on your X400 build. :wink:

[Hotshot Charlie]

Thanks Lakespinner for all the info ! I will keep everyone posted when the building starts !

[WayneBrown]

I had mine set;
normal 0-70-100
idle up 100-100-100
"S" curve pitch in all modes
HS 55 on tail, gyro at 45% HH zero drift in normal. 10MM out for the linkage with 0 delay, Set limits to just stalling the servo right and left.
The only time it wagged was when; A.) the horizontal fin rotated and caused drag on the pushrod or B.) the tail slider was dry and needed oil.

A new frame and misc. parts and it'll fly in an hour or two again.
BTW: all stock HDE with Align 420LF and Align 35A esc with woodies or mavvrik carbons. I tried a Himax 2025-5400 and spun it so fast the links split...

[Hotshot Charlie]

This may have been covered.... but....

Make sure the 401 is set out of the "digital" servo mode. If you are using a standard HS50/HS55/S75 on the tail.

I'm really not sure what it would do if in the "digital" setting.

Just a thought.

[Curtis Burns]

I reset my curves and moved the gyro to the "normal" place on the fuse and that fixed it. I guess the speed control and motor was giving my gyro hell. I also bought a GY240 for it and put my 401 back on my backup heli.

Thanks for the help

Curt

[matrix_mimi]

I reset my curves and moved the gyro to the "normal" place on the fuse and that fixed it. I guess the speed control and motor was giving my gyro hell. I also bought a GY240 for it and put my 401 back on my backup heli.

Thanks for the help

Curt

Yes, I had same problem as well. Don't use the ARK/Helimax ESC with Futaba 401. :arggg: 401 draws way too much current than this cheap/weak ESC can supply. I fixed this problem by using a cc phoenix 35A ESC. I also tried using a cheaper gyro. telebee, that I have sitting around. With some major tweakings, it works fine also.

[femi]

This is exactly the problem am experiencing currently with my MX400, :arggg: the tail just keeps spining left just before mid stick collective, its already cost me one of my blades; I'VE TRIED EVERYTHING, from revo mixing, to offset, to ccpm throtle to rudder (slave) mixing, servo throws to subtrims :arggg: Somebody,please somebody HELP ME!!! give me a detailed step by step tail/Gyro set up procedure; Tx=DX6 Spectrum; Gyro GY190 (Futaba)

[femi]

HURRAY, HURRAYyyyyyyy, Guys, I've finally resolved my MX400/DX6 Specktrum tail/Gyro Problem. :lol: And you know what, i couldn't have done it without the help of all of you guys here at the forums. :lol: The answer lay simply in the set up of the DX6 Spektrum; Get rid of all revo mixing; rudder subtrims; GER (Ch. 5) switch channel endpoints; progammable mixes; and simply connect the GY240 to rudder channel after cross-checking (1) that rudder servo is at neutral and (2) correct rudder servo throw direction. Re-cross check correct rudder direction with gyro connected with AVSC off. If fine, put gyro to HH and reconnect to rudder channel 4 (DX6 tx). Nothing to it. CAUTION; all DX 6 tx users, make sure TX is properly set up; that was my mistake; neutralise GER channel switch in flight mode to -0/+0 at both ends of the switch; set rudder offset function in programmable mix menu to 'OF'.

As for the DX6-my verdict is- its a fantastic Tx. :smokin:


THANKS A MILLION AGAIN GUYS, AM FINNALY AIRBORNE, AIRBORNE, AND ALL THANKS TO HELIFREAK. :noteworthy