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Aerial Photography and Video > HeliCommand Autotrim

DenisS
Key Veteran
Location: Essex, UK

OK, I understand... the bar should be in the middle when down and 80% when up. Good
I haven't heard about the autotrim being active when collective is above 50%. That wouldn't make any sense at all!! Leave it as you have it, that will be good.
You don't have to press the SET button when using autotrim. The SET button must ONLY be pressed when the heli is on the ground. The autotrim works while the heli is in the air. Whatever you do, DON'T TRY TO HOLD THE 'SET' BUTTON WHEN THE HELI IS ABOUT 50 FEET UP

You shouldn't have to set the autotrim in all modes (NOR, POS and HOR) although the autorim CAN be used at any time. You have to hover for at least eight seconds to get the internal sensors settled, then hit autotrim. After that the memorised autotrim will be recalled when you hit the switch again.
The way I get the servos to centre is to set the helicopter up WITHOUT the Helicommand installed using the TX system swash menu (i.e. 3s 120, 3s 90 etc), then when all sticks are in the centre, including collective pitch, the servo arms can be positioned. Some subtrim is allowed for fine adjustments when you have installed the Helicommand and changed the swash back to 1 servo in the system menu, but remember to press the ' SET' button down for a second, until the gree light goes solid, to set the neutral position.
Denis

Crash 'n Lurn

11-07-2008 08:55 PM

nooobs
Key Veteran
Location: Toronto, Canada

Quote
How are you setting up your servos to 90 degrees initially to setup the head with HC? I am used to using subtrims to center the servos, but now that HC is doing all the mixing I am not sure how to do it.

Butters, you should be able to center your servos and level your swashplate mechanically with the HC installed. Find the correct servo horn position to center.

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I haven't heard about the autotrim being active when collective is above 50%. That wouldn't make any sense at all!! Leave it as you have it, that will be good.

You'll know when Autotrim is active when the red light is flickering.

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SET button must ONLY be pressed when the heli is on the ground.

I believe you could only press the set button while the heli is on the ground.

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The autotrim works while the heli is in the air.

Well technically you could also enable autotrim while on the ground.

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Whatever you do, DON'T TRY TO HOLD THE 'SET' BUTTON WHEN THE HELI IS ABOUT 50 FEET UP

Please explain how you can hit the set button while the heli is 50 ft up in air.

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After that the memorised autotrim will be recalled when you hit the switch again.

Incorrect. It does not recall. When Autotrim is "hit" it resets new trim values for the specific attitude of the heli.

11-07-2008 09:39 PM

HOMEPAGE

butters149
Senior Heliman
Location: monterey park, ca

So what mode should I be in when I hit autotrim? If i do autotrim for HOR, and i change to Nor or Pos is it going to change?

I cannot get my servo horns exactly 90 degrees without subtrims. It will be a little off, can i use my TX to add subtrims then press set button until 1 flashing greeN and disconnect battery?

Also lets say if I do the autotrim once, and then again, is the 2nd one going to overwrite the first one? Or should i wipe out all the trim by calling up setup via the "set" button?

11-07-2008 09:57 PM

nooobs
Key Veteran
Location: Toronto, Canada

Butters

You can hit autotrim in ANY mode.

If you change modes, either Horizontal or Position, it won't affect the last autorim values.

Yes, by hitting autotrim again, it will overwrite the last autotrim values.

You have to understand what AUTOTRIM does.

You know how you have "trims" on your TX? Well AUTOTRIM does what your trims on your TX does.

If you were trying to hover for a long period in one orientation, without HC and lets say there is a bit of a consistent wind, of course you could either fight it with cyclic or add trim. So this is where AUTOTRIM comes in.

Same scenario: You're trying to hover with a bit of wind. Before you flick the autotrim switch you would need to hover for about 8 seconds. What this does it sets the artificial horizon within HC. You then momentarily flick the autotrim switch. You should notice the heli hovering in the last attitude the heli was at.

Normally I would set autotrim 2 or 3 times to get it just right. The first just gets your fingers off the cyclic. The 2nd and 3rd autotrims refines the hover.

[EDIT]

In addition to the AUTOTRIM, if you have to hover in a different orientation, you will have to "autotrim" again. The last autotrim values will act in the opposite direction.

This is where most people get confused and wonder why their heli drifts so much. You must "autotrim" everytime you change the heli's orientation if you want to hover for long durations.

11-07-2008 10:12 PM

HOMEPAGE

butters149
Senior Heliman
Location: monterey park, ca

What exactly do you mean "heli orientation", the reason why i ask if the trims will stick to hor or pos is because on the dx7 if you change flight modes itll change, trims, unless you have the trims and sliders all the same for each flight mode i.e. nor, idle 1 and idle 2.

So the way my diagnose screen and endpoints, etc are ok so far correct?

11-07-2008 10:53 PM

DenisS
Key Veteran
Location: Essex, UK

noobs

Have you heard about the collective activating autotrim above 50% That was his question. If you are above 50% on collective you would normally be in the air so would not see the red light flickering. Yes, you can set autotrim while on the ground but there is no point

As for pressing the 'SET' button while 50 ft in the air..... did you see the three grinning faces at the end of the sentence??? I'm sure butters did and he realised that I was joking, but maybe you are now? Anyway, if you do want to hit the set button while 50ft in the air I suggest a loooong stick with maybe a coathanger bent round to miss any sticky out bits on the helicopter, then you should be able to hit it OK....

My understanding of autotrim is that, after hovering the helicopter steady for eight seconds the trim values are stored within the Helicommand without you having to activate a switch. Then, after flying around if the heli drifts when coming back to the hover you 'recall' the automatically stored value by a quick flick of the switch.
From the Helicommand instructions :
The automatic trim function requires around eight seconds of steady hovering in order to record the correct trim values; they can then be called up immediately by pressing the trim button
I interpret that to mean the Helicommand does the trim storing, you just recall it with a switch. I'll ask Joachim at Captron to clarify it.

Butters, yes you can use TX subtrim with the HC fitted, just hold the set button for 1 second till the green light goes solid after you have set the subtrim to tell the HC of the new neutral value (see section C at the bottom of page 22 in the instructions). You have to hover for eight seconds each time you want to change the autotrim value so it shouldn't change when you change modes. Only if you want to delete any stored autotrim values should you do the set up procedure.
But I could be wrong
Denis

Crash 'n Lurn

11-07-2008 10:56 PM

butters149
Senior Heliman
Location: monterey park, ca

so do i only do the autotrim once then? i mean its going to recall it automatically for every flight right?

11-07-2008 11:13 PM

nooobs
Key Veteran
Location: Toronto, Canada

Quote
What exactly do you mean "heli orientation

What I mean by different heli orientations is your heli's nose is to the left, right, nose in or tail in are various orientations.

Quote
the reason why i ask if the trims will stick to hor or pos is because on the dx7 if you change flight modes itll change, trims, unless you have the trims and sliders all the same for each flight mode i.e. nor, idle 1 and idle 2.

I'm not familiar at all with the DX7. I do realize you are limited with your channels. I have seen HC set on a DX7 though.

I believe the HC was setup only for one mode. (horizontal or positional) Basically we determined position hold was not required by this person so we set one switch for horizontal.

You should NOT set the flight modes (Normal, Idle1, Idle2) with AUTOTRIM. This will mess you up.

You should have two switches available to you if you're using the internal gyro. Set one switch for AUTOTRIM and the other for horizontal.

You will have to set a curve for the horizontal hold as the DX7 does not have a slider. Correct? The curve will determine your horizontal gain when activated. Remember you also have to set the gain in the software.

Denis

Quote
Have you heard about the collective activating autotrim above 50% That was his question. If you are above 50% on collective you would normally be in the air so would not see the red light flickering.

You wouldn't want to be in AUTORIM mode all the time. AUTOTRIM is meant to be activated for a second.

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Yes, you can set autotrim while on the ground but there is no point

Yes there is use for this. Obviously you haven't encountered such a situation. I've had the Rigid sit around for a long time. This affects the sensors within HC. I tried to take off for the first time and realized the heli wanting to tip over. I hit autotrim while on the ground and was able to take off. So there is use for it.

Have you wondered why you have to hover for 8 seconds? The artificial horizon within HC is dynamic. It's constantly adjusting according to the heli's attitude. So obviously after flying around you may be hovering in a different orientation/attitude or wind speed and direction may have changed and HC's artificial horizon would have changed and therefore you will have to "AUTOTRIM".

11-07-2008 11:18 PM

HOMEPAGE

butters149
Senior Heliman
Location: monterey park, ca

http://www.heliguy.com/Forum/autotr...1,start,25.html

check out the post from "Trooper" about 6 posts from the bottom, he shows a pic too, says somthin bout minimum collective pitch etc and autotrim activation etc.

11-07-2008 11:19 PM

butters149
Senior Heliman
Location: monterey park, ca

I didnt mean to set them all with autotrim, i meant that if I autotrimmed in no modes (I have my dx7 set for 3 modes) is that autotrim going to effect the pos. and horizonal hold? or would I have to switch to Hor, then autotrim, then switch to Pos then autotrim etc? I am having autotrim on a seperate switch so its not going to interfere with any of the Holds.

11-07-2008 11:23 PM

nooobs
Key Veteran
Location: Toronto, Canada

As I mentioned previously, you can AUTOTRIM in any mode. Horizontal or Position.

11-07-2008 11:39 PM

HOMEPAGE

butters149
Senior Heliman
Location: monterey park, ca

yes but what im saying is, if i autotrim in pos mode, and i swsitch to hor mode, is the settings going to effect the hor mode as well? or will it drift in hor mode?

11-07-2008 11:54 PM

nooobs
Key Veteran
Location: Toronto, Canada

If you're using Position Hold then of course you'll be very low to the ground. If you're still low to the ground and switch to horizontal hold the autotrim values shouldn't change. BUT your heli may or may not drift as it's no longer using it's optics to lock onto the ground.

Also remember if you're hovering low and turn the heli around now you've changed the heli's orientation and so you may have to autotrim again.

Hovering low to the ground versus hovering at 100 ft are two different situations. You should autotrim again if you're going to hover at a higher altitude.

If you're doing circuit flying, then hover, then autotrim again.

11-08-2008 12:13 AM

HOMEPAGE

Lorax28
Heliman
Location: Portland Oregon

Hey Noobs, what if there was no wind and you changed the orientation, would that have an effect?? I'm going thru this in my head because the other day I was trying to get the autotrim to work and couldnt see a change attitude. I did keep the heli pointing in the same direction, there was wind but, every time I hit the trim I would let the cyclic return to center and the heli would drift the same as before I hit the switch. It didn't seem to trim. I have the red light flikering and when I hit the switch I am holding the heli in a fixed hover with the cyclic. Then let the cyclic after a short time center out and there goes the heli, I have to the hold the cyclic back to a hover it. I assume that when you hit the switch the cyclic would be in what ever possition it needs to be to keep the heli in a tigh hover, and I expect after the 8second hover and activation of the trim switch I should the be able to relax on the cyclic by letting it return to center and it should act as if I trimmed it. Do I have to be out of HOZ and POS modes to auto trim or can I auto trim in any mode regardless?

11-08-2008 03:46 AM

nooobs
Key Veteran
Location: Toronto, Canada

Quote
what if there was no wind and you changed the orientation, would that have an effect??

In theory no. It depends on how the HC unit is installed. If you spin the heli 180° has the angle of the HC changed? Both front to back and left to right? We're talking about a PERFECT install. How is the CG of your heli?

Quote

I'm going thru this in my head because the other day I was trying to get the autotrim to work and couldnt see a change attitude. I did keep the heli pointing in the same direction, there was wind but, every time I hit the trim I would let the cyclic return to center and the heli would drift the same as before I hit the switch. It didn't seem to trim. I have the red light flikering and when I hit the switch I am holding the heli in a fixed hover with the cyclic.

When you engage AUTOTRIM you only have to engage it for a brief second. It's simply back and forth on the switch. If you hold the autotrim switch one way the red light will keep flickering and will not set the trim values and therefore will not "trim".

Like you said there was wind. Wind is inconsistent. This is a misconception of HC. HC WILL NOT HOLD YOUR HELI IN ONE SPOT. You have to correct with minor cyclic input.

I've flown my Trex in 60Km+++ wind and have been able to hover. Of course the heli was in a wild attack angle towards the wind. Even with the help of HC constant cyclic correction was still needed.

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I assume that when you hit the switch the cyclic would be in what ever possition it needs to be to keep the heli in a tigh hover, and I expect after the 8second hover and activation of the trim switch I should the be able to relax on the cyclic by letting it return to center and it should act as if I trimmed it.

Yes. Again, if there was wind, slight cyclic correction is still needed.

Quote
Do I have to be out of HOZ and POS modes to auto trim or can I auto trim in any mode regardless?

You can AUTOTRIM anytime in ANY mode and as MUCH as you want. Again, as I mentioned earlier, I autotrim 2 to 3 times to fine tune the hover. Sometimes more due to caffeine... LOL

11-08-2008 05:58 AM

HOMEPAGE

Lorax28
Heliman
Location: Portland Oregon

I guess when I was trimming it I expected once the auto trim was switched a few moments would go by and I would notice the heli want to move opposite the direction the cyclic is in and that would cause me to alow the cyclic to go to neutral. hope that makes sense. CG on my heli is spot on. Tough even if it was off the trim should account for that i would assume. I am running my HC on a vario gasser. Ive installed the HC according to the manual to a T. It works great on HOZ mode which is what I fly it in 100% of the time. I have a vary smooth running Gasser. Thanx for the info.

11-08-2008 08:07 AM

dleroi123
Senior Heliman
Location: Old Lyme, CT

There are some mentions of autotrim happening at 50% collective and I don't know if it was ever cleared up. Here's my opinion:

There's a setting called "Autotrim Inhibit" that inhibits autotrim unless the collective is above mid-stick (or, where ever HC thinks mid-stick is). It's inhibited even though the red light blinks when you initiate autotrim. So if you hit autotrim on the ground, it doesn't change the autotrim values. I don't know if this is explained in the manual, but you can verify it in the software. First go to the "Diagnose" tab and look in the "Various" box. At zero collective the "Autotrim inhibit" box is checked. Move the collective above mid-stick and the box gets unchecked. Now, tilt the heli to make sure it isn't in the same orientation it was the last time it was autotrimmed. Then, go to the R/C & Trim tab and look at the "Internal autotrim settings". Hit autotrim with the collective stick down, then read in the new settings. They don't change. Now, go above mid-stick with the collective and repeat. The new settings appear. In both cases the HC blinks red.

There was also some confusion about what happens when you hit the autotrim switch. Again, you can verify this in the software. Hitting the switch (above mid stick) causes HC to read, store, and use the current orientation as neutral. It doesn't do this automatically and then go to those settings when you hit the switch. Each time you hit the switch, it grabs the current settings and uses them.

Again, these are my takes, so if anyone knows differently, please feel free to correct me.

-Don

11-08-2008 03:26 PM

butters149
Senior Heliman
Location: monterey park, ca

where can i get the software that shows all the check boxes? i tried downloading a couple 1.34.3 versions but to no avail.

11-08-2008 03:55 PM

dleroi123
Senior Heliman
Location: Old Lyme, CT

Butters,

Hmm... that's the right version. I got mine here:

http://en.helicommand.com/index.php...id=55&Itemid=62

By the way, you have to have the PC interface cable plugged in and the HC fired up to get into the "Diagnose" tab - that's where you'll find the check boxes I mentioned.

I've found using the software to watch what's happening with the HC to be invaluable. It's like the RealFlight for learning the HC.

- Don

11-08-2008 04:16 PM

Qinetiqemc
Heliman
Location: Somerset - UK

Just managed to catch up with all the extra posts.
Lots of great information.
dleroi123
Your explanation of autotrim above a certain collective setting is what I have found out as well. The manual confirms that it shouldn't be enabled on the ground at zero collective.
butters149
I had problems installing version 1.34.3.0 on a Vista PC, the previous version 1.34.2.0 had the problem:
'After (automatic) windows update with .NET Framework 3 or 3.5, tooltips had disappeared'.
Eventually copied the .exe file from an XP PC to Vista PC.
As Don said you should be able to get it from his link OK.

Ian

11-08-2008 05:41 PM

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