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Topic Review (Newest First)
05-13-2009 07:57 PM
Thi-rex Very useful information, guys. Centering the slider will give some pitch to counter-act the main blades, which would hold the head at base (servo) position. Nice. I'll just follow SoKal's instruction and center the slider at 90-degrees. I think I missed Finless' comment in the video that the "zero-tail-pitch" = centered slider for the ALIGN Models only....
Cool, I'll set it up this way and start the GY401 with 70 gains to see if there's any drift or tail-wag, and then I would adjust the gain correspondingly.


Again, thanks a lot everybody
05-13-2009 07:46 PM
Blade~400~er
Quote:
Originally Posted by Thi-rex View Post
Your step 4 & 5 are kinda time consuming and rather complicated. I thought we just increase the gain until there's no "drift" left?

hmmm....."time consuming and rather complicated".....welcome to the hobby!...lol
05-13-2009 07:37 PM
Wolfpackin The GY401 is very simple to set up.
Just center the pitch slider on the shaft while the servo is centered in Rate mode.
Set the limits for no binding then fly in HH and adjust gain.

It's that easy, no need to worry about Rate mode hover unless you intend on flying in Rate mode.

Both Sokal's and the Finless video linked by 1BADAIR show this.
The G401B works the same way for those that have it.
This is much more simple than the G110 and even the LTG2100T.

Just let the 401 decide where to put the slider for hover.
It will do so as long as it has equal travel in both directions.

Please note I'm not saying a Rate mode setup for no yaw won't work because I know it will, it's just not necessary in the case of the GY401.
05-13-2009 07:25 PM
1BADAIR finless FTW
http://video.helifreak.com/tmp/ecdb5...otherhelis.wmv
05-13-2009 07:13 PM
macel 401 and b 400. the trick is to set it up mechanically.

i.e. set subtrim to 0, set travel adjust to about 75 % which gives you a nice and easy turn (piro) rate, travel adjust does NOT extend the travel distance of the servo with the 401 inbetween, but the speed with which the tail will move left or rate, don't forget to give it 75 % LEFT AND RIGHT (you need to change both figures)

make sure you don't have any trim on your dx6i trim knobs (below the rudder stick..)

than make the belt tight correctly

put the servo into neutral position, (power it up ..... ) and don't forget to switch off that motor.........., now you set up the servo horn AS CLOSE TO 90 ° as it gets, IT WILL ALMOST NEVER EVER BE EXACTLY 90 88 or 92 i do usuall tend to go to 92 °
DO NOT USE SUBTRIM TO GET SERVO HORN TO 90 !!!!!

just let it sit slightly over or under 90 °.

than put in the tail pushrodlink.

on one side ou can adjust the length (tail side) on that rod.

now you want to face your tail blades about 2 degrees towards the boom, (like in turning to the right or so that the tail moves left.....) . usually that gives me a rock steady tail....... if you try to set it up with out pitch heli will turn left (tail will always try to push to the right....)

now you might not be exactly in the middle of the shaft. what you can do now is to move the tail blade grip holder a bit up or down on the shaft (the flat spot is about 4 mm long., i.e. you can adjust a bit there)

DON'T worry if one side is a bit shorter than the other.

now you power it up, you take a tiny screw driver or other pin like tool and
you adjust the max. travel distanc on the little screw nob on to p of the 401 casing.
what you do is give full right and full left stick input on the TX
whilst holding it at full right or full left you adjust on that little knob (marked limit) on the 401 until the shorter side at full stick input does just slightly touch BUT that the servo doesn not titter....... i.e.

younormally will have to adjust the tailblade side as it will hit the limit before the tailboomside.....
don't worry that you have approx 2 mm spre on the left side....... doesnt matter

now go hover it if it tails pulls right or left, just shorten or lengthen the tail pushrodlink, to adjust.

do not use trim knob.......... any trim settings will screw up the behavior of the 401...... in HH mode.

OH YEAH DO SET UP THE TAIL IN NORMAL MODE (NOT HH MODE, I.E GAIN UNDER 50 %...........) ...

AND than i hope you heard abt the 3 times flicking trick before lift off in HH mode.....
05-13-2009 06:41 PM
meatbob The G110 cannot compensate for a built-in drift in HH due to a pushrod that is too long. Merely increasing gain won't fix anything with this gyro.

Yes - it is time-consuming, but once it's done, you will have a tail that is as locked-in as one can get with the G110.

Since the OP is using a GY401, the above steps really don't apply.
05-13-2009 06:17 PM
Thi-rex Your step 4 & 5 are kinda time consuming and rather complicated. I thought we just increase the gain until there's no "drift" left?
05-13-2009 06:11 PM
meatbob Even if the slider is dead center when the blades are still, the gyro will tend to push the slider over to counteract the torque when in a stable hover. You will always need some pitch (not nearly zero, but somewhere in the single digit degrees) to counteract the torque in hover.

Here's what I do (with G110 stock gyro)

1. Set servo horn to 90 (no subtrim)
2. Adjust length on rod to get centered pitch slider on shaft
3. Switch to standard rate mode, say 43% on Dx6i Gyro Gain.
4. In normal mode, float the bird at a near hover, and adjust rudder trim until it holds.
5. Shut down rotor, and replace rudder trim with either lengthening or shortening of the
rudder rod.
6. Repeat 4 & 5 until the tail holds in normal mode and in hover, with gyro set to
standard rate mode.
7. Switch to HH mode, and you should not have any drift. Any drift that does occur can
be removed by repeating 3-6 above.

If you decide to increase your piro rates by expanding your travel endpoints, you'll have to re-adjust as above, since you'll be multiplying the small errors in the linkage by the increase applied to the endpoints.

I never worry about the centering on the shaft after step 2 - it's really just a stepping stone to a drift-free tail.

Since you are using the GY401 - have you watched Finless' video on setting this up?
05-13-2009 05:53 PM
Thi-rex Ok, so I take it as everyone's suggestion to get the slider at the center of shaft when servo is 90-degrees......and have equal and full range in both directions on the shaft when the servo swings back-n-forth? I was thinking that this make sense too - just let the gyro make the necessary pitch/angle adjustments to hold the tail.

Other additional comments are welcomed
05-13-2009 05:39 PM
Blade~400~er
Quote:
Originally Posted by Niko View Post
In general, at zero pitch the blades should not be centered in the slider. Thats because the pitch curves for the tail are not centered about 0. The pitch curves are centered about the amount of pitch needed to hover.

+1....the tail blades should have just a tiny bit of pitch in them when the slider is dead center on the shaft.....blades with 100% neutral pitch produce no thrust, thus a tiny bit is needed to maintain a stable hover
05-13-2009 05:12 PM
Niko
Tail pitch curves not cemtered about 0 pitch

In general, at zero pitch the blades should not be centered in the slider. Thats because the pitch curves for the tail are not centered about 0. The pitch curves are centered about the amount of pitch needed to hover.
05-13-2009 04:52 PM
meatbob Yes - the Blade 400 does not have a built-in pitch offset when the slider is at the center of the travel range. Now, your Travel extents determine Piro rate; I would not necessarily worry about binding on either side unless you plan to slam the tail around. The Gyro in HH mode will filter your inputs and provide the pitch required to satisfy your desired inputs in conjunction with the ATV settings.

I fought with this for a few packs until I realized what was going on.
05-13-2009 03:02 PM
Bob O When I set up my heli/gyro for no drift in rate mode, the slider is significantly off center. No way around the issue for me.
05-13-2009 01:16 PM
Thi-rex
Tail pitch is not Zero at center of shaft :( :(

I have a question on installing the GY401 + S9257 for the Blade 400. The problem is that I cannot get the tail blades to be at zero pitch when it is midrange of the tail shaft. If I try to adjust the linkage rod so that the tail blades are zero pitch when the (9257) servo is at 90-degrees, then I would have tons of travel distance/space on the left and about 1/2 of that for the right side. As the result, the GY401 Limit Setting can only go up to 80 before the slider binds with the right side. Should I follow Finless videos and aim for zero-pitch at 90-degree and take a loss on the travel limit, or just make the slider at center of the tail shaft at servo's 90-degrees and bump up the gyro limit (I'm looking at 100 or so)? I have spent a lot of thought on correcting this without choosing one between the two, but the only way it seems like is to either make the slider's arms longer or find a longer shaft rather than using these stock parts....So please advise me what to do if you can.

Thanks in advance,

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