FBL Gyro Assan GA250 issues??

[PYNES1664]

Hi guys,
I have one of these MEMS gyros and can't get on with it, It's in my 250GT and the tail wags like something dimented! I have the gyro TX gain now down at 25% and it still wags, I haven't even tried heading hold mode as I don't have enough confidence in this gyro to try it. It's stuck down to the horizontal plate at the rear of the 250 above the receiver with a single pad.

Am i missing something here, does it have to have a particular orientation? or might it be vibration - though the heli doesn't appear to vibrate unduly.
Interestingly when holding the heli in a normal flying attitude whilst spooling up to 50% and above the tail servo does appear to 'hunt' around centre as if the gyro is making strange inputs. Servo is a HK orange digital (HKSCM9-5)

can anyone shed any light on this please as it has me baffled currently.

thanks in advance

Rich

 

[coolgabsi]

hey... sucks to hear that man!

two things... you say you have not tried Head hold (HH) on it yet. Means you are on rate mode... and you have vibrations on rate mode??? I would definately try rate mode... thats the mode you usually fly in... so see whats up with it... I would try it.. if you can control it now you will be able to control it then at 50 percent or whatever throttle. Secondly The tail wag is on the ground or the air? on the ground sometimes, my 450 gives a wag too... its just because the skids have friction with the ground. So it happens.

Now The orientation of the gyro.. I bought my 250 (now i sold it) from Tony.. the owner of this site. It did not have tail wag. He had the same gyro installed on it too.. The orientation of the gyro was on the same plate where the RX is sitting on the bottom probably and the gyro sits on top, the gyro is standing upright.. not lying down...

I installed another gyro on it .. the exceed one, and it was working fine only when it was standing up. I am not sure exactly as to why.. may be someone else would be able to shed some light on it.. But, try that..

I have heard that 250's have a BUNCH of tail wag but its all setup based issue. Setup right a heli wont do it. Not questioning your setup, but telling you GA250 should hold pretty good.

Tony himself had (or has that) installed it on some of his BIG birds. I hope this helps. Let us know how it goes.

 

[Lee]

May not be your gyro. Read this review from HK.
I purchased four of these servos for the cyclic and tail functions of my new HK450 v2 heli. During setup and initial checkout, I was pleased with the centering and speed of these servos. Also, they made very little noise.

Sadly, when I began the operational tests of my heli I could not figure out why the tail of the heli would track okay when it was coming up to speed on the ground, but then the tail would suddenly "freak out" around 75pcnt speed. Upon further diagnosis, I realized that the servo was not strong enough to control the tail at those speeds. Needless to say, the servo burned out and seized in about five minutes...possibly from being overworked.

So far they seem to be strong enough for the cyclic. I will see how they hold up in time.

For now, I would say leave these servos to the airplanes!

 

[breeze400]

You have to run your gyros in heading hold not rate mode. Rate mode is for 3d flying. You have to remember set your transmitter gyros rate at about +65 on 0 and -65 on 1 on your gyro switch and go from there. Spool up on 0 and see where you are. If no wag increase to +70 and try there. When your tail starts to wag then reduce by a few points till it stops. Also check with Tony on how and where to mount the gyro.

Remember on your transmitter anything above 50% is heading hold anything below50% is rate hold!

 

[Tony]

If you are using the DX6i, then 25% is a LOT of rate. Move that up to 60%. Remember, 50% is like there is no gyro on the tail. From 50%-100% is head hold mode. And 50%-0% is rate mode. The farther you get away from 50%, the more travel the gyro will have.

 

[PYNES1664]

hi guys,
apologies for the late reply, weekend was a blur! Daughters 8th birthday party and I don't think iv'e recovered yet. No time for any flying either but hey.......kids

Anyway, here's a picture of the gyro in place and it's orientation relative everything else as i'm not totally suer that I understood you Gaba.

The wag is VERY evident when airbourne, and not at all on the ground, to describe it's like the gyro is giving a spurious input, say to the left then immediately compensates with right, the ossicilations get gradually worse to the point of unflyability (is there such a word??)

Tony, yes it's a DX6i and I am clearly confused! on my 450 I always fly with the gyro switch in the up position (0) rate mode where the gyro gain is set at 35%, I presumed the same for the 250 and set these the same, however the 450 has the 401 Gyro.

I presumed that lowering the figure to 25 was ion fact reducing the gain! clearly not, i'll try adjusting it nearer 50 then judging by that.

Should I be flying in switch position 1 then - set at 65%?? and if so why?

Excuse my pathetic understanding of this, I clearly missed that lesson

Do you reckon there is any mileage in swapping out the gyro and putting this one on my 450 to rule out any of the mechanical setup/servo etc? I'd hate to as the 450 flies so well but perhaps needs must.

thanks guys and really appreciate the input

- Rich

 

[PYNES1664]

Iv'e just had a wild thought, would headspeed have any effect? I only ask cos i'm running 2S whereas (I think) most guys run the 250 on 3S.

-Rich

 

[Tony]

Here is what I was told about rate mode and HH mode.

In rate mode, the gyro will only stop the movement of the tail. It will not return it back to where it was before the movement started. This is great for scale flying, but if you get hit in the side by a gust of wind, the tail will move, but it will only counter the movement and try to hold it still.

HH, or heading hold mode is just that, it tries to hold it at one heading unless told otherwise by the rudder stick.

so lets say that you can hovering above a clock. the nose of the heli is at 12 O'clock. If you are in rate mode, and wind hits the tail and moves the nose to 9 O'clock, it will just stop the nose right there at 9 O'clock. But, if you were in HH mode (above 50%), and the wind blew the nose from 12 to 9 O'clock, the gyro would return the nose back to 12 O'clock.

if this is hard to understand, just let me know and i will try to find a better writeup on it.

 

[PYNES1664]

Actulally that makes perfect sense, I'm just talking to Lee and he's pretty much said the same thing. I am totally mystified why nobody else has ever mentioned this at the club, and even more worrying is that iv'e NEVER got this from anything that iv'e ever read on the subject. In truth I have reaslised that I am clearly totally thick. my degree in software engineering was clearly a lot easier than i though

 

[Tony]

It took me a while to grasp how the gyro's work. But, once you learn, you know it forever.

 

[llommel]

I have an e-razor 450 that I can't seem to get the gyro working the way I think it should. I made a turntable & mounted the 450 on the turntable. When I spool up the heli, it pretty much stay heading in the same direction. If I give it a small amount of right or left stick, it turns but when I return the stick to the center, the tail will keep on spinning & keep on going faster. I've got the DX6i set up per Tony's video. Need some suggestion please. I have a video of the heli mounted on the turntable but don't know how to post it on here.

Thanks, Lloyd

 

[Lee]

Ok from what you have said, it sounds like the gyro is reversed. Instead of it correcting the spin the gyro does the opposite and that intern makes the tail spin faster and faster.
To show the video, you first have to upload it to youtube or vimeo, then paste a link on here for us to see it.

 

[llommel]

Thanks, Lee. To reverse the gyro do u go into "gyro" on the TX & change "N" to "R"?

 

[Tony]

No, you have to do it in the gyro it's self. Its one of the programs. and to post a video, you will have to upload it to YouTube. I don't have enough server to host videos.

 

[llommel]

It has the GY192 gyro on it, how do I reverse it on the gyro? Looks like the only setting on the gyro is the gain screw.

 

[Tony]

The 192 you just flip over. I thought you had the 250...

 

[llommel]

I got it operating, no more spinning. Like you said Tony, just flip it over. Now all I have to do is get the throttle & pitch curve set for my level of flying,
which you can tell is very low.
Hopefully by the time I get in some flying time, I'll have some hair left that I didn't pull. Thanks again for the great help.

 

[Tony]

Any time bro. Just let us know when you need it. And I shave my head for this reason lol.