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attitude change on trim


Blackeye

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When changing the attitude of the Hind and cycling the trim button on the new attitude/stick position the AP channels do change attitude after that.

 

For example when trimmed for forward flight (nose down) then pulling the nose on the horizon with the cyclic and then trimming, the Hind pulls the nose up even more, despite the cyclic being in the same position (center trim option). This effect isn't always as pronounced as at the end of the clip but still unexpected when comparing it to the Mi-8 for example.

 

OB patch 2.7.4.9632

demo3.trk

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Experiencing this aswell, before and after 2.7.4 patch.

 

It feels like the trim system doesn't realign on the current attitude after releasing the trim button.

 

Can't really describe the behaviour but it's definitely weird, very wonky and unstable compared to the Mi-8.

 

 

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Ok, just did some testing and i think this describes the issue quite well.

 

https://imgur.com/a/GdnVWpW

 

Pay attention to the controls indicator for the cyclic and autopilot channels, aswell as the picture's descriptions.

 

In a nutshell: Releasing the trim button will have the autopilot pitch and roll channels snap back to their original center,
rather then accepting the new trimmed position of the cyclic as its center.

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Remember you got thicker shorter heavier rotors than the MI-8 and the winglets that take up 20% (?) of the lift off the rotor blades.

The MI-8 will not fly like the aerodynamically superior hind with its winglets offering massive lift gains.

Not to mention the massive energy stored in the blades...... Just saying.

 

#The MI-8 is no Hind.

 

I often wonder if we would have such conversations comparing the huey to an early cobra AH-1.... I think not.... and I wonder why?


Edited by Rogue Trooper

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1 hour ago, Rogue Trooper said:

Remember you got thicker shorter heavier rotors than the MI-8 and the winglets that take up 20% (?) of the lift off the rotor blades.

The MI-8 will not fly like the aerodynamically superior hind with its winglets offering massive lift gains.

Not to mention the massive energy stored in the blades...... Just saying.

 

#The MI-8 is no Hind.

 

I often wonder if we would have such conversations comparing the huey to an early cobra AH-1.... I think not.... and I wonder why?

 

 

This isn't a question about aerodynamic traits. This is a systems question about how the cyclic trim interacts with the Autopilot.  Either the cyclic trim is supposed to work as a single click at the desired attitude, like the Mi-8, or else, you're supposed to hold the trim in while you are changing from your present attitude to your desired one like the in the Shark.  Right now, a quick click on/click off of trim, as you would do in the Mi-8, interacts with the autopilot enough to cause an annoying oscillation.  This is a fact.  The only way to properly trim the Hind at present is to operate the trim exactly like you would in the Shark, which is surprising to a lot of us, because in the absence of any other information, one would naturally assume that it would behave more like the Mi-8.  That assumption could be wrong, and obviously if that's how it operates in real life, then so it shall be, but I haven't read anything thus far that provides an answer to how it is supposed to work.  

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13 hours ago, Ornithopter said:

 

This isn't a question about aerodynamic traits. This is a systems question about how the cyclic trim interacts with the Autopilot.  Either the cyclic trim is supposed to work as a single click at the desired attitude, like the Mi-8, or else, you're supposed to hold the trim in while you are changing from your present attitude to your desired one like the in the Shark.  Right now, a quick click on/click off of trim, as you would do in the Mi-8, interacts with the autopilot enough to cause an annoying oscillation.  This is a fact.  The only way to properly trim the Hind at present is to operate the trim exactly like you would in the Shark, which is surprising to a lot of us, because in the absence of any other information, one would naturally assume that it would behave more like the Mi-8.  That assumption could be wrong, and obviously if that's how it operates in real life, then so it shall be, but I haven't read anything thus far that provides an answer to how it is supposed to work.  

 

I've tried both ways, I find it weird either way. It just doesn't seem to end up in the attitude I trim it at, I'm constantly fighting it. 


Edited by jonsky7
grammar
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Am 22.7.2021 um 17:16 schrieb bertOC:

Ok, just did some testing and i think this describes the issue quite well.

 

https://imgur.com/a/GdnVWpW

 

Pay attention to the controls indicator for the cyclic and autopilot channels, aswell as the picture's descriptions.

 

In a nutshell: Releasing the trim button will have the autopilot pitch and roll channels snap back to their original center,
rather then accepting the new trimmed position of the cyclic as its center.

indeed it does, which is - as bug-reported for 3+ patches now - odd.
While the mechanical solution for the trim are more or less hydraulic actuactors  in the 24-p arresting the cyclic and the torque pedals (part of САУ-В24-1 - "Cистема автоматического управления" - Automatic control system), those very AP channels (ВУАП-1 - Вертолетный унифицированный автопилот [Unified Helicopter Autopilot]) are the actual electronic component of the Trimmer system (actuating the cyclic and the torque pedals to achieve/maintain trim states as mandated against outside condition changes).

But this might be either an isolated bug or just a buggy downflow-behaviour since the latest patch seems to have a general FM issue as I tried to describe here:


But the "trim overflow", the occasional "cyclic-lock" with still working hat-trim across all 3 peripheral modes has been present since the first early access... if only if only there was a proper bugtracker for this to get actually looked at systemically (and if there was a will to do so... instead of this tendency to too often register bug reports as offensive operations to personal sensitivities and attitudes.... Eagle really is still a very very strange corporate entity... sometimes...)


Edited by rogorogo
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Experiencing this issue whereby the helicopter pulls up and left slightly if I push cyclic forward and left, to fly level and moving forward, then trim and release the stick immediately. It's somewhat difficult to fly these past few days without using manual, untrimmed cyclic control.

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25 minutes ago, ColinM9991 said:

Experiencing this issue whereby the helicopter pulls up and left slightly if I push cyclic forward and left, to fly level and moving forward, then trim and release the stick immediately. It's somewhat difficult to fly these past few days without using manual, untrimmed cyclic control.

 

Just forget about the trim button and use the trim hat and manually trim/offload control forces. As the Hind flies with a relatively neutral cyclic anyway there is not much trimming required for 'normal' flight. Is how you fly a MD500 and it works fine - just constant little stabs at the trim hat will give you nice hands-off control. Obviously larger trims required as you slow for landing etc, but you have plenty of time.

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16 hours ago, VampireNZ said:

 

Just forget about the trim button and use the trim hat and manually trim/offload control forces. As the Hind flies with a relatively neutral cyclic anyway there is not much trimming required for 'normal' flight. Is how you fly a MD500 and it works fine - just constant little stabs at the trim hat will give you nice hands-off control. Obviously larger trims required as you slow for landing etc, but you have plenty of time.

 

That is typically what I'm doing now, the issue with trim button is mainly seen when I'm coming in for a vertical landing and I pull the stick aft and right before using the trim button as it's quicker.

 

Anyway, as long as the issue is reported and has some weight behind it so it's being picked up and patched.

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  • 3 weeks later...

It is important to find a balance between the cyclic and collective before activating trim. This is true for all helos, but more so for the Hind.

This bird flies pretty straight and true without trim. If you are pushing forward a lot to remain level, your collective is too high.

The same is true if you are pulling back to keep the nose up, your collective is too low.

 

First off, I don't recommend large curves on your axis settings. Depending on your equipment +10 to +15 on the pitch & roll and 0 on the collective and yaw will do. 

I make sure that I'm flying straight and level and that the side slip ball is centered without trim before I press the trim button.

All I need to do then is simply use the trim hat to fine tune it and I am hands off in just a few seconds.

My HOTAS only has one hat switch which I use for view, so I mapped my up, down, left & right arrow buttons to this axis.

 

zppBciB.png

 

The trims and auto pilots are not interconnected. They are separate systems. What you do to one will not affect the other.

I do recommend using the "Rudder Trimmer" option as it makes life so much easier and it's really not a cheat. It is there to compensate

for the lack of hydraulics in spring centered pedals. In the real bird, rudder trim is called pedal dampening.

If you have FFB pedals then I recommend using the pedal dampener, otherwise use the "Rudder Trimmer".  

The Yaw AP is very useful when taking off and landing as well as holding a set heading.

This is also not a cheat. It is installed by the manufacturer for a reason;  well, two actually. It is a heading hold for long trips and most importantly,

it is to compensate for the Hind's natural tendency towards LTE during take off, landing and hover in certain wind conditions.

 

To takeoff, first I pull my stick back a little and to the right and set it in with the trimmer.

 

 wNJTTqN.jpg      

 

Then I turn on the Yaw AP and lift off straight up in a hover and rotate to my desired direction of travel.

Then at about 100 feet. (30m) altitude I press the trim reset button.

When the trim returns to center, the nose will drop slightly, but that's exactly what I want. It starts me accelerating towards forward flight 

without having to push forward too much on the cyclic. I level off with the VSI on 0 and the side slip ball in the center.

Then I press the trim button, release the stick for a second and then fine tune with the hat. If I do it right, I don't get the sudden deviation when trimming.

It has already happened when I went from takeoff attitude to forward flight. BTW, if you press and hold the button, like on the Ka-50, the nose also drops , so................

 

On 7/22/2021 at 6:29 PM, jonsky7 said:

I've tried both ways, I find it weird either way. It just doesn't seem to end up in the attitude I trim it at, I'm constantly fighting it. 

 

If you are fighting it. you are doing something wrong. You are probably not balanced between stick and collective.

There is no interaction between trim and AP. One does not affect the other, but both affect the whole.

Try flying without trim, get it as close to straight and level as you can, then press trim and fine tune with the hat.

 

This is a large and heavy bird. She doesn't respond well to hard and fast inputs. Be gentle with her and she'll be gentle with you. Don't manhandle her.

If you find it hard to get her back in line after a while, she may be damaged. Turn off Yaw AP, reset trims and start over.

The many adjustments you make while flying along are accumulative. The trim reset may just be your best friend.

 

A common theme/complaint across all these threads is "The Hip doesn't do this or that or the Huey or the Ka-50 etc, etc, ad infinitum, ad nauseum. 

Stop comparing her to the Kamov, the Hip or the Huey, she is neither. She has her own personality. You must learn to deal with her on her own terms.

 

On 7/22/2021 at 6:14 PM, Ornithopter said:

 

This isn't a question about aerodynamic traits. This is a systems question about how the cyclic trim interacts with the Autopilot.  Either the cyclic trim is supposed to work as a single click at the desired attitude, like the Mi-8, or else, you're supposed to hold the trim in while you are changing from your present attitude to your desired one like the in the Shark.  Right now, a quick click on/click off of trim, as you would do in the Mi-8, interacts with the autopilot enough to cause an annoying oscillation.  This is a fact.  The only way to properly trim the Hind at present is to operate the trim exactly like you would in the Shark, which is surprising to a lot of us, because in the absence of any other information, one would naturally assume that it would behave more like the Mi-8.  That assumption could be wrong, and obviously if that's how it operates in real life, then so it shall be, but I haven't read anything thus far that provides an answer to how it is supposed to work.  

 

 

This is a systems question about how the cyclic trim interacts with the Autopilot

Wrong, they don't interact. They are separate systems, they each do their own job, but both apply to the whole bird.

 

"like the Mi-8 - like the in the Shark - as you would do in the Mi-8 - operate the trim exactly like you would in the Shark "

See what I mean about comparing to the other birds, sorry Dude,  I don't mean to pick on you, but you said it all in one post.

The hind is not any of those other birds, so stop comparing. Those other three aren't like each other, and neither is the Hind like any of those.

An eagle is not a robin, or a crow, or a sparrow, or a hummingbird. 

Accept her for who she is, not what you want her to be.   Apologies to Ornithopter,  rant over.

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If you are pushing forward a lot to remain level, your collective is too high. The same is true if you are pulling back to keep the nose up, your collective is too low.

 

No, it usually means you want to go fast or slow respectively - unlike an aircraft you need to hold the stick deflection to maintain the current attitude.

 

Quote

The trims and auto pilots are not interconnected.

 

Watch the AP channels in DCS when you press and release the trim button - they definitely interact with the trim button.

 

Quote

If you are fighting it. you are doing something wrong. You are probably not balanced between stick and collective.

 

Nope - the attitude jump happens even when you go from one completely stable flight attitude (trimmed) to another stable attitude held with stick at the moment you cycle the trim button.

 

Quote

The trim reset may just be your best friend.

 

It's cool that you've found a way for you to work around the issue, but I don't think the whole thing is supposed to work this way in the real Hind, hence the bug report.

 


Edited by Blackeye
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I have this bug happening regularly to me as well I think. In options center joystick trim, no rudder trim. Yaw, roll and pitch AP on. Starting in trimmed, stable flight, I then change attitude and regain stable flight while holding the controls. Once stable (all parameters, so also climb/descent and airspeed), press the trimmer and release the joystick to center (holding pedals in position since no rudder trim). Most of times the airframe keeps stable and the trim works as I expect it to, but there are also many times *something* happens which messes up the trim entirely. It feels as if it sort of doubles the input I tried to trim, so e.g. if I was giving 20% cyclic forward, I trim and center the joystick, the moment the joystick is centered suddenly another 20% forward stick is added. I don't know how to reproduce this, it seems happening randomly, but made me crash already several times when it happend while going in for a landing.

 

Sometimes I can fix it by re-trimming another time, but there also are times only a trim reset and re-trim can "fix" it. If I've not already crashed and burned...

 

Before it's asked:

- No, no RBS (happens in any attitude, speed, etc.)

- No, no VRS (happens in any attitude, speed, etc.)

 

Stick is a TM Warthog, no extensions and when the bug occurs it's definitly fully centered and most definitely not giving the "over-input" that is happening.

 

I'll see if I can make a .trk when this occurs again. Might as well be a pilot error, but at least I'm glad to read more people are having this issue which makes me think it isn't entirely me who's doing something wrong.

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Blackeye right. The difference between the Mi-8 and Mi-24 autopilot is that in the Mi-24 the trimmer interacts with the autopilot, the SAS signal is reset to zero when the roll and pitch channels are trimmed. The developers admit the bug, we are waiting for changes in the update.

 

 

"Accept her for who she is, not what you want her to be".  When I read this, it seems to me that  rayrayblues  is writing for himself. There are a lot of incorrect arguments. 


Edited by Mins
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