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Old Sep 24, 2012, 07:13 PM
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Question
Need help with tail setup on a 600.

Hi,

I have a Trex 600 clone and need help with my tail setup.

I use a Futaba S9254 servo and a HobbyKing 401B gyro.
(DX8 transmitter)
It's not the gyro I need help with, the tail is solid as a rock!

I have setup/trimmed the gyro by the book, and am happy with the result.
But can't figure out how to solve my rudder movement issue.

When hovering and rudder is in neutral position, it is compensating for yaw movement and therefore are closer to one side.
When making full rudder the heli will yaw much quicker in one direction.
The rudder stick is also more sensetive in one direction.
Is there a way to compensate for this?

Yaw is also a bit slow in one direction... would bigger tail blades prevent this?

Thanks!
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Old Sep 25, 2012, 02:04 AM
bein ebin
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Australia, QLD, Brisbane
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Are you sure the tail rotor blades are placed in the right direction ? I guess one of the blade is placed wrong ? Just assuming.
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Old Sep 25, 2012, 04:28 AM
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United States, MO, Springfield
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use rudder end points on the radio to set the piro speed ether up the slow side or lower the fast side or a little of both
after that add some expo on the rudder channel i like about 15% on the rudder some like more but 15 to 20 % is a good starting place
same with cyclic start with 30% expo if you havent
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Old Sep 25, 2012, 03:25 PM
Need More PURPLE !!
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Just my opinion..That hk-401b gyro should not be used on a 600 size heli. In short dont put sub-par electronics on a 600. Its just begging for a disaster or an injury.
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Old Sep 26, 2012, 06:27 AM
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Quote:
Originally Posted by Stixx44 View Post
Just my opinion..That hk-401b gyro should not be used on a 600 size heli. In short dont put sub-par electronics on a 600. Its just begging for a disaster or an injury.
Only a fool would argue against this.
Pretty much the hole heli is China clone stuff, but some vital parts that are Align originals. That is what my budget covers... but I only fly on big fields where there are no other people near.

Quote:
Originally Posted by Elios000 View Post
use rudder end points on the radio to set the piro speed ether up the slow side or lower the fast side or a little of both
after that add some expo on the rudder channel i like about 15% on the rudder some like more but 15 to 20 % is a good starting place
same with cyclic start with 30% expo if you havent
This makes sense.
But maximum rudder in one direction does not make the heli yaw enough
I think bigger blades might help?
Higher RPM also, but then I must change pinion gear or motor. I'd rather not.

Quote:
Originally Posted by ebinmoothedam View Post
Are you sure the tail rotor blades are placed in the right direction ? I guess one of the blade is placed wrong ? Just assuming.
Well, they are both in the "right" direction. But your comment gave me an idea.
Maybe I have twisted the tail belt 180 degrees wrong. That would make the tail rotor to spin the wrong direction. And maybe the tail rotor mechanism is made so that in hover, the tail rotor thingy* is in the middle.. and that is why it is not in the middle now?

In what direction is the tail suppose to spin?
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Old Sep 26, 2012, 07:05 AM
bein ebin
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Australia, QLD, Brisbane
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The main rotor blade spins clockwise looked from top with tail pointing you and tail rotor blade counter clockwise when you look at the blade from the right side.

I have read some where else, that few helicopters spin the other way too.

Kindly confirm.
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Last edited by ebinmoothedam; Sep 26, 2012 at 07:20 AM.
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Old Sep 26, 2012, 09:39 AM
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Quote:
Originally Posted by ebinmoothedam View Post
The main rotor blade spins clockwise looked from top with tail pointing you and tail rotor blade counter clockwise when you look at the blade from the right side.

I have read some where else, that few helicopters spin the other way too.

Kindly confirm.
Am at the office now. Will check when I get home.
Thanks!

How about changing to bigger blades?
Or his higher RPM a better way dealing with this?
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Old Sep 26, 2012, 01:32 PM
just gotta mess with it!
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Quote:
Originally Posted by Windman View Post
Am at the office now. Will check when I get home.
Thanks!

How about changing to bigger blades?
Or his higher RPM a better way dealing with this?
Since the tail blades are working against the main rotor torque reaction, you might expect the tail to turn quicker with torque, i.e. to the right, than it does to the left. There are a few things you can do to make sure that the tail is properly set up.

First of all, make sure that the limits have been set in the gyro to give you full deflection in the tail slider, without binding. When you do this, however, you shouldn't go beyond 45 degrees of tail rotor pitch - otherwise the tail rotor will stall and just suck up power whilst feeling mushy.

Also make sure your tail blades are the right way round - it amazes me that a heli can still fly with the tail blades on backwards, or the belt twisted the wrong way, but it usually makes a tell-tale odd sort of noise that alerts you to it.

Second, as Elios000 said, you can equalise the piro rate by adjusting your tail servo ATV's or end points in the TX. It's quite normal to have a greater ATV setting for left rudder than for right. For example, on my 450, I have 113% ATV for left rudder, 103% for right. The easiest way to fine tune the ATV's is to have the heli set up on a "Lazy Susan". Small changes in ATV value can have a big effect.

Another thing that will affect tail response is headspeed. As the headspeed increases, the tail rotor gets disproportionately more powerful. That's why, for example, a 450 Pro, optimised for higher headspeeds, has a smaller ratio of tail rotor to main rotor speed than say the 450 Sport. Now you can't generally adjust that tail/main ratio, but if you run a low headspeed, you will lose tail rotor power. So make sure your HS is in the normal range, which for a 600 should be 1700 - 2200. I use 1750, 1850 & 1950 on a 600N.

You can fit longer tail blades. I've always read that the threshold for doing that is when the tail gets "blown out" in say a tailslide or piros in fast forward flight.

Good luck!
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Old Sep 26, 2012, 01:56 PM
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Windman: If your dead set on useing this gyro. Ther is a hot glue mod for hk401-b. ( see you tube) in short take off the back of the gyro and fill it with hot glue. It has solved many of users problems in the past.
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Old Sep 26, 2012, 02:39 PM
just gotta mess with it!
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North West Louisiana
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Quote:
Originally Posted by Stixx44 View Post
Windman: If your dead set on useing this gyro. Ther is a hot glue mod for hk401-b. ( see you tube) in short take off the back of the gyro and fill it with hot glue. It has solved many of users problems in the past.
I used a 401b in a beater 50 size nitro heli with no problems - but the hot glue mod is an easy and sensible precaution to take.
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Old Oct 07, 2012, 04:14 PM
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Thank you all for great answeres!
Gave me a lot to think about...

I had already done the "hot glue fix" for the 401b gyro.
I have pretty much all setup the way I want it to.
...except for ONE THING, the tail authority when yawing counter clockwise is still way to low.
One turn clockwise takes like 1/5 of a second, one counter clockwise takes 2-3 seconds.

I have 93mm carbon fiber tail blades.
Main gear is 170T and pinion is 10T. Ratio 1:17
And a 1100kv motor that runs on a 6S battery.
I dont have a rpm meter, so theoretical calculations:
(1100kv*22.2V)/17 = HS 1436rpm/min

* There is a 13T pinion with same modulus (0.7) that fits my motor (5mm shaft). This would give HS 1867rpm.
* There is also a nice set of tail blades in carbon fiber for a trex 700. They are 105mm.

Could these two items be smart "upgrades" to get better tail authority?
Should give about 40-50% more "effect" on tail blades, right?
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Last edited by Windman; Oct 07, 2012 at 04:44 PM.
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Old Oct 07, 2012, 07:53 PM
just gotta mess with it!
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North West Louisiana
Joined Nov 2009
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1436 is definitely at the low end of usable HS for your 600, and tail authority will improve noticeably with higher HS. You should try a larger pinion. On 6s, people use anything up to a 17t. With your 10t, you will only see about 1300rpm, allowing for some load on the motor. 13t might give you up to HS1700, 15t up to HS2000. I think the 10t pinions are aimed more at 1400kv motors.

What are your rudder ATV settings in your TX? Have you tried using higher ATV to speed up the piro rate?

You can use larger tail blades, but you may find that you don't need to if you increase the HS. If you still want more tail power and do go for the longer blades, you might need to consider a longer vertical fin.
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Old Oct 08, 2012, 07:25 AM
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Regarding the HS, a 15T pinion sounds lika a wise choise.

That raises another question. Can my motor handle it?
I have this motor:
Turnigy Typhoon 600/1100kv

I have a watt logger, so I could adjust pitch to match current draw with the new RPM.
I dont really need more power (not for now anyways), I'm only looking for better tail controll...
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Old Oct 08, 2012, 07:53 AM
just gotta mess with it!
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I think you should be OK - there are several reviews on the HK site that say they're getting good results with a 15t. So long as you use the wattmeter and watch your top end pitch, and keep within the capacity of your ESC, you should be fine.
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Old Oct 08, 2012, 08:45 AM
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motor is fine real question is what ESC? also might want to think about running 8S or 10S
600s are hard on 6S packs
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