Heading Hold or Not

[mathsinstrument]

When do you need to use the heading hold? When do you not use the heading hold function?
I know i have to set the gyro in Non-Heading Hold mode, but why can't i fly without heading hold? What type of flight will I not use heading hold? Scale? 3D?

[9VDXN]

I shall use this analogy...


You are driving an auto transmission vehicle with option to override with the tiptronic manual shift..

When do you have to use the auto transmission function?
When do you want to use the manual override?
Why can't u manually shift? Answer: Yes you can...by all means...
What type of driving pattern do you want to use manual shift?



Hope I answered your questions....

[probasz]

i turn off 401 heading hold to calibrate Gyro and center all arms,links and check for slop and turn on back for a smooth consistent tail

[CKS]

i turn off 401 heading hold to calibrate Gyro and center all arms,links and check for slop and turn on back for a smooth consistent tail

also take note that calibration of gyro with HH turned off has to be done indoor (least windy environment)

[mathsinstrument]

I understand the analogy.
Then when do you use it? Heading Hold for 3D? Can non heading do 3D?
What can non-heading hold affect flight characteristic?

This qn popped out of my head when i was flying my shuttle with a GY240. It seems to fly better and have more responsive tail control on non-heading hold than turning that on.

[Art]

correct me if I'm wrong but when there's an input on the rudder the HH will be off....HH will be most useful in straight FFFs and strong wind hovers...

[9VDXN]

HH is developed to make rudder control easier.
It's like auto transmission vehicles are developed to make driving 'easier', but also have it's pros and cons....

Sometimes HH is a bit too 'keh-kiang', just like auto transmission vehicles...eg. during strong & windy conditions sometimes you give rudder input but it just refuse to move, or there'll a slight delay.

However, if setup properly, HH shouldn't be inferior or make a noticible difference to the flight characteristic as compared to non-HH mode....

non-HH mode should be slightly more difficult to fly coz you need to manually do your heading hold. I would think that non-HH response for rudder input will be faster.

In your case, i think your HH gain is too high, that's why u felt that non-HH mode works better for u.....try to re-setup your rudder again...

[9VDXN]

and for my flying style, 3D, flips, hovering, invert, FF or backwards flight, etc....I almost never used non-hh mode......the only time i toggle to non-HH is when I am trimming my heli once I feel that the HH is starting to drift.

I did try flying around & inverting in non-HH mode b4, but I feel that it's drifting too much to give me a predictable maneuver..... I'm just too used to the luxury of HH mode.

[9VDXN]

correct me if I'm wrong but when there's an input on the rudder the HH will be off....HH will be most useful in straight FFFs and strong wind hovers...

Yep, HH is only activated when there's no rudder input, indicated by the red light in GY401...cannot remember if GY240 does have it..

Any rudder input will disable the ACVS system momentarily in the gyro as mentioned in the manual.

[moveon]

This is how I feel. When I turn off HH on my Trex, it feels like flying a honeybee microheli. Lots of tail drifting and when correcting with rudder input, the tail will not hold after correction.....

[Swashhead]

240 vs 401

9VDXN wrote "Yep, HH is only activated when there's no rudder input, indicated by the red light in GY401...cannot remember if GY240 does have it.. "

The GY240 is known to have weaker response to the rudder input (i.e. have slower piro rate) than the 401. I believe the HH function of the 240 is also on when there is rudder input resulting in weaker rudder control.

This is one reason why we always recommend new heli buyers to get the 401.


Swashhead

[aerobird]

I understand the analogy.
Then when do you use it? Heading Hold for 3D? Can non heading do 3D?
What can non-heading hold affect flight characteristic?

This qn popped out of my head when i was flying my shuttle with a GY240. It seems to fly better and have more responsive tail control on non-heading hold than turning that on.

Personally, I prefer to fly without HH. I only turn on HH when I'm taking off or about to land.

The reason why normal flying (not 3D), is easier without HH is because the heli will behave more like a plane in forward flight. For example, making a turn withOUT HH requires little or no rudder input. With HH on, a simple bank and turn requires co-ordinated rudder input to turn the head of the heli with the curve of the turn.

In HH, the heli will not weathervane.

For 3D, reverse flying, and any manuveres where you don't want the heli to swing around without your commands, then HH would be turned on.

[aerobird]

9VDXN wrote "Yep, HH is only activated when there's no rudder input, indicated by the red light in GY401...cannot remember if GY240 does have it.. "

Swashhead

That's not really true. Once HH is on, it will be performing in AVCS mode whether you have rudder input or not.

You can do a simple experiment for those of you with the Gy401 or any gyro that can switch between HH and normal.

In Non-HH mode, inputting rudder in any direction will cause the servo to move, and then return back to center. When you swing the heli left/right, the servo will move in the direction to try and counter the swinging effect. But the servo will ALWAYS return to center.

In HH, moving the rudder sticks will cause the servos to command the heli to move in the appropriate direction. Even if you return the rudder sticks back to center, the Servo will NOT return to center. As far as the gyro is concerned, you have commanded the heli to turn, and it is waiting for the heli to do just that.

If you now take the heli and twist it slowly in the direction that you commanded the rudder sticks, you will find that the servo will slowly return back to the center. Once it reaches center, this is the new heading of the heli. Trying to turn the heli more than the required heading, the Gyro will now command the servo in the opposite direction. The more you turn the heli, the larger the gyro input to the servo will become. HH gyros can be seen like a auto pilot that knows which direction it is facing. It will always command the rudder to get it back to that heading no matter what. Because of this, HH mode allows you to hover with a direct 90 deg cross wind with no effect at all on the tail drifting into the wind.

[probasz]

well in my case since heli and airplane are not the same in many ways
flying without heading hold is like driving a car on a slippery road.

[mathsinstrument]

Thanks for all the information!

Then what about Single Rate Gyros? Are there any Dual Rate Gyros? What's the difference?