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HelicopterRadio - Servo - Gyro - Gov - Batt › 9Z CHD help needed
09-03-2003 11:26 AM  14 years agoPost 1
donlynn

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New Zealand

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Gidday

I am trying to figure out how to use the CHD function / Condition hold

As I understand when selected you select the max throttle you want then your sweet .
The trouble I have is when I select it the throttle always drops away to next to nothing and usually the heli dies,

What am I missing please as I can see the advantage of this when trying to adjust the idle up curves with the motor going.

Thanks for your time

Regards Don

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09-03-2003 01:17 PM  14 years agoPost 2
Angelos

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nr Oxford, OX11, UK

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CHD sets a max trottle limit so that you can switch to other conditions without the engine RPM going high. Set the limit a bit higher and you will be fine. By the way... perhaps your other flight condition has very low throttle curve and this kills the engine. CHD is a max limit not a fixed throttle value.

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09-03-2003 09:31 PM  14 years agoPost 3
donlynn

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New Zealand

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Gidday Fellas

Thanks for your input.

The engine dies even if I stay in normal and while at idle activate CHD
it also dies if I activate CHD in normal with a very fast idle.

It seems the only way I can keep the engine going is to activate when at approx 1/3 - 1/2 throttle this works but the engine dies when I lower the collective / throttle. As suggested I also feel the botttom stick trim position is too low in CHD and am unsure of a work around.
I havn't switched to idle up while CHD is active as I figgured it best to get CHD working correctly in normal before trying another mode also.
Currently I stop the engine to adjust my idle up curves
How do I adjust the bottom stick trim position in CHD ?

Thanks again

Regards Don

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09-03-2003 10:39 PM  14 years agoPost 4
MJA

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UK

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There is a workaround which gives the same thr trim as throttle hold,but it isn't as safe as using CHD, as there is no warning tones given while active or a warning of throttle position when you try to switch out of it.

What you can do is set up another Hold switch in every flight condition with the HLD menu item.When the switch is thrown it allows all the programming etc even in idle up,but with the throttle trim position taken from throttle hold,however you must remember to switch out of idle up and lower the throttle(stick) enough before throwing the switch back to normal or the engine will bark in.Same rules really as remembering not to switch out of thr hold whilst currently still in idle up with heli on the deck or whilst starting up
Also the switch will act like another throttle hold switch as far as the throttle is concerned
so don't hit it accidently whilst in flight at an inopportune moment:-)
The good thing about it is you don't do all that pissing about pressing CHD then ACT or INH'ing to get in and out of condition hold.This all works because of the fact that the Hold condition itself has a higher priority than the other conditions in the condition list ,so even though you tell it to be another switch in HLD than the one that's setup in CSL, the original Hold switch still works and overides the flight modes ok

As for the very low idle in CHD,i'm not 100% sure why that's happening.
What i would do though is make sure your throttle trim is linked in all the flight modes ie Normal mode throttle trim matches throttle hold trim,in TRM the T3 should be set to ATL-C (Combined mode)

Also in HLD i think weird trim **** happens when you have the mode (top left) set to other things other than Manual mode.Getting throttle trims to match can also be a nightmare if you have a volume control set in HLD,the trims will only match when the slider/rotary is in the middle


Martin

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09-04-2003 02:00 AM  14 years agoPost 5
donlynn

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New Zealand

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Gidday

Thanks alot fellas !

Yes I have a seperate idle speed when in hold
to enable a nice clutch disengaged idle I use the RS (right slider).
I also use hold for starting
I may have a balls up in the hold sysytem as there is a throttle hold (THD) which I did use but the throttle speed was affected by the rknob which I use as a throttle adjust at hover when in normal.
So I turned all this to zreo and now use the hold curves in COND menu PCV and the hold curve in TCV, I wonder if this may be doing the lowering of the throttle in CHD ?

I'll have a look through the menus tonight and see if i can locate
the right place to
"Memorize the current throttle trim to memory C>M."

and check the following
"throttle trim is linked in all the flight modes ie Normal mode throttle trim matches throttle hold trim,in TRM the T3 should be set to ATL-C (Combined mode)"

I'm struggling a little with this radio, 2 weeks now but I really like the ability to prog mix ail -thr and ele - thr differently in normal or idle 1

my curves are getting close !
thanks for all your help.

Regards Don

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09-21-2003 01:11 PM  14 years agoPost 6
donlynn

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New Zealand

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Gidday

Done the C - M current to memory .thing several times in normal, idle up and while in hold.
T3 is set to ATL-C (Combined mode)

tried doin git in normal then activating CHD then lowering collective to idle and the motor stops ??

the throttle goes low enough to stop the throttle at bottom stick.
normaly I need to hit the kill swith to stop the motor ?
It's like once activated the throttle position is reduced by 10 % ??!!

Thanks for your thoughts .

Regards Don

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09-21-2003 10:57 PM  14 years agoPost 7
Peefor

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Norfolk UK

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Gidday Don

'Fraid I do not have the solution, but can confirm my set behaves exactly the same. I, too, have tried all the suggestions listed.

The percentage in CHD can be set to any value up to 100, but the throttle is still moved to the stop position when CHD is active.

Just confirms the problem. We are fortunate in having a ZAP Guru in our club, and he is baffled as well!

Pete

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09-21-2003 11:37 PM  14 years agoPost 8
MJA

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UK

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Don,
If you allocate a switch to be an extra/new thr-hold switch you can use this as a condition hold sw for radio idle-up etc programming and do away with the software CHD option in the radio.You would defianetly no longer have the low throttle problem as it takes the throttle position directly from thr-hold condition.It has some dangers associated ,but really just takes getting used to the same as remembering not to hot start the heli in idle-up or switching straight out of throttle hold into an idle-up with a high throttle setting.

Another possible thought i have had since was that if you imported your radio where it was really a different "factory" supplied Mode and it has had a simple Mode 1 to 2 or vice versa change where just the stick spring and stop plates have been transposed
it may need the sticks calibrating properly with the model gadgets service menu enabler

Martin

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09-22-2003 01:09 AM  14 years agoPost 9
donlynn

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New Zealand

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Gidday

Martin ,I think you are on the money !

I too rekon the center is out a little as when I'm setting up my curves at middle stick the wee arrow curser is off a couple of mm, not a biggee really but that would explain it - thanks :-)

Maybe a mix to throttle increasing it the ~10 % driven by spare switch then if I fiddle with it in flight it'lll only increase my thr by 10 % ( not a biggee) rather than put it to idle and I'm coming down ready or not.

So is the menu enabler the only way rather than turning the pot shaft a wee bit in the joystick housing ?

Thanks again

Regards Don

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09-22-2003 04:56 PM  14 years agoPost 10
MJA

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UK

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Don,
It isn't bound to fix CHD problem but might be worth a try,i'd have thought it more likely that the stick endpoints be showing adrift rather than the middle ,if it's had a quick and dirty Mode change.But it should be in the middle with default throttle curve & no subtrim on thr channel .The hovering throttle trim needs to be centred too or it'll show to be off in the middle

For what the service menu enabler costs,probably safer to use it instead of ratching around inside the tx.If you adjust the sealed pot that's under the plastic plate i think it'll shift the whole range which may then leave it short at one end on the pitch/throttle graph screen.Might be worth checking it is still sealed up and hasn't slipped,not very likely if it's never been touched from new.
The service menu enabler re-calibrates/re reads the current pot/stick range so the software knows the stick limits.

all the instructions on what it does and how to buy are on this site

http://www.model-gadgets.com


Martin

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02-23-2004 10:29 AM  13 years agoPost 11
donlynn

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New Zealand

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update

Gidday

Further to my inability to operate the CHD function.

I had my 9z in for recalibration at a fellow fliers (a radio tech )
Ultra pac, tried the reclaibrate but it still wouldn't calibrate, so he manipulated the joystick pot in relation to the joystick position until the cursor in the TCV was in the middle when the stick was.
Now all is Perfect and The CHD is working sweet as.

Thanks to all for your help.

Regards Don

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HelicopterRadio - Servo - Gyro - Gov - Batt › 9Z CHD help needed
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