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Old 10-22-2019, 05:21 PM   #11
heloguy
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Quote:
Originally Posted by M1Combat View Post
I don't think either of you are understanding what I'm trying to say. No offense meant... maybe I'm not explaining it well.

All I'm asking is that you test with a very small trim offset (When the AP channels are exerting very small amounts of control authority to maintain trimmed attitude) and with a large trim offset (when the AP channels need to exert somewhere near their maximum control authority to maintain air frame attitude). This will be valuable information.

I'm just seeing both of you perform a minor test that doesn't prove anything and certainly doesn't prove any "cause" for what you're seeing.

I'm not saying "there is no issue here... move along...".

I'm saying "Test, test, Test. We'll find a bug IF it's there AND we'll have a good bit of info about what settings, procedures and even environmental factors affect it"

Until you do that... NOBODY will be convinced . If you want someone to be convinced... you need to do the leg work . That's all .


Also...

The oscillation I'm talking about is not what you're talking about. I'm talking about any free body's natural tendency to oscillate around an equilibrium. It's basically the concept that no motorcycle or aircraft EVER can go straight. EVER. It doesn't happen. That's the oscillation I'm referencing. Not what happens here when you re-trim the KA-50. I'm going to stop trying to make the point though because I don't think that either of you have the background knowledge to get the reference. Please don't take offense..

That said... I'll try to find an explanation and I'll post it here.
Don't worry, no offense taken. I also perfectly understand your attempted explanation of the phenomenon. I just don't agree that it's correct behavior in the simulated aircraft system/flight model. Mainly the aircraft system, as the flight model acts just fine when I take the ka-50's trimmer out of the equation, and simply trim using the hardware feature of my joystick.

The oscillation is easily reproduced, and is shown many times within the already posted videos. The oscillation increases in magnitude directly proportional to the amount of time the trimmer button is depressed, to a certain degree that is able to be arrested by opposite pitch in the stick.

As for background, I assume you could mean engineering. Not sure if that's the case, and no, I don't have an engineering degree. I have been flying various helicopters for the last 13 years, though, admittedly not a ka-50. I have also been playing/flying the DCS Black Shark for almost the same amount of time (12 years IIRC).

In a no wind gust situation, in a stable hover, it is possible to get a near zero oscillation hover. The small corrections required to maintain a stable hover without gusts are quite negligible compared to the oscillations in pitch experienced in the current Beta version of the DCS Black Shark when using the trimmer. The oscillations are not something I remember when playing the game initially, or until recently.

Frankly, I'm not concerned about convincing you there's a bug. I would just like someone from ED to run their own test, and confirm whether or not it's a bug. The oscillation is there, whether you perform a small re-trim, within the 20% as you say, or if you just hold the trimmer button down for a few seconds.
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Old 10-22-2019, 05:50 PM   #12
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"I also perfectly understand your attempted explanation of the phenomenon. I just don't agree that it's correct behavior in the simulated aircraft system/flight model. Mainly the aircraft system, as the flight model acts just fine when I take the ka-50's trimmer out of the equation, and simply trim using the hardware feature of my joystick."

No you don't.

As I said... "The oscillation I'm talking about is not what you're talking about. I'm talking about any free body's natural tendency to oscillate around an equilibrium. It's basically the concept that no motorcycle or aircraft EVER can go straight."

I'm talking about how you initially set the trim affecting what happens during a re-trim. You're talking about what happens when you re-trim.

The issue you're talking about isn't even an oscillation. It's a possibly errant control input coming from somewhere.

Again ... I'm not convinced it's not a bug... I'm just trying to explain a method to isolate where it's coming from so we can go to the dev's with more info rather than less.
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Old 10-23-2019, 04:29 AM   #13
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Let's stop the pretentious "I am so smart" bullshit. We're talking about an inconsistent behavior with the trimmer, not the natural oscillations that would occur in not only motorcycles and aircraft, but any moving mechanical device. It's like we're discussing an issue with bicycle handling, and you're trying to contribute by throwing out info on rubber adhesion to asphalt.

Getting back on topic, I looked into this some more and the pitching issue seems to only occur severely when the trimmer mode is set to Joystick without Spring and FFB. Here's a video of the the trimmer mode set to Default. I start by holding down the trimmer and changing the attitude significantly, then release when I have it stable. After that, I periodically hold down and release the trimmer without moving the stick, and the aircraft gradually pitches up each time towards the 0 pitch line, which I believe is just the aircraft's natural tendency to straighten out:



The same effect can be seen with trimmer mode set to Central Position Trimmer Mode, it gradually moves towards the 0 pitch lines and stays there:



It's only when the trimmer mode is set to Joystick without Spring and FFB where the aircraft starts to pitch significantly in either direction and is too large to be considered natural:



It seems that if the aircraft is going to pitch up, it will do so when the trimmer is released, and if it's going to pitch down, it does it when the trimmer is first pressed. I believe the bug is with how Joystick without Spring and FFB mode handles the trim presses.

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Old 10-23-2019, 05:24 AM   #14
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Quote:
Originally Posted by Ranma13 View Post
Let's stop the pretentious "I am so smart" bullshit. We're talking about an inconsistent behavior with the trimmer, not the natural oscillations that would occur in not only motorcycles and aircraft, but any moving mechanical device. It's like we're discussing an issue with bicycle handling, and you're trying to contribute by throwing out info on rubber adhesion to asphalt.

Getting back on topic, I looked into this some more and the pitching issue seems to only occur severely when the trimmer mode is set to Joystick without Spring and FFB. Here's a video of the the trimmer mode set to Default. I start by holding down the trimmer and changing the attitude significantly, then release when I have it stable. After that, I periodically hold down and release the trimmer without moving the stick, and the aircraft gradually pitches up each time towards the 0 pitch line, which I believe is just the aircraft's natural tendency to straighten out:



The same effect can be seen with trimmer mode set to Central Position Trimmer Mode, it gradually moves towards the 0 pitch lines and stays there:



It's only when the trimmer mode is set to Joystick without Spring and FFB where the aircraft starts to pitch significantly in either direction and is too large to be considered natural:



It seems that if the aircraft is going to pitch up, it will do so when the trimmer is released, and if it's going to pitch down, it does it when the trimmer is first pressed. I believe the bug is with how Joystick without Spring and FFB mode handles the trim presses.
That’s the exact test I thought of today at work, suspecting it may have something to do specifically with the trim mode. Thanks for checking that out, and I’ll see if I can replicate.
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Old 10-23-2019, 06:26 AM   #15
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Just tried it with the MSFFBII - no pitchup at all.
At a stable altitude and 240km/h, actually a very slow slight nose drop if the trimmer's held in, nothing else.

Do you have curves set on your controllers ?
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Old 10-23-2019, 07:12 AM   #16
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No curves set, though it shouldn't matter since I'm not moving the stick. If the nose is dropping very slightly, it sounds like you're getting the same behavior as I am with trimmer mode set to default or central.
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Old 10-23-2019, 10:13 AM   #17
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Maybe - it doesn't drop with a jerk though, it just slowly starts to drift down if I hold the trim in for more than a second.

No curves - Good (in that at least it eliminates something), but using curves does make a difference if you're actually using FFB, as the FFB is set to always assume no curves for providing the FFB for the trimmed position (the FFB assumes a linear relationship between real stick position and SIM stick position, but with curves that doesn't exist), and so the trimmed position & reported position of the stick end up misaligned if FFB is on and there are curves set on the pitch and roll axis.

That would mean there was a tension between the point the aircraft's AP was trying to align to and where the stick was trying to fly the aircraft to, and one side of that tension would be relaxed every time the trimmer was pushed...


There are threads about it and E.D.'s advice is no curves with FFB sticks...
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Old 10-23-2019, 12:58 PM   #18
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No curves in my case either. My setup is currently (and has been throughout this conversation) force feedback disabled, using ‘Joystick with no springs or Forcefeedback’ trimming method.

Quote:
Originally Posted by Weta43 View Post
Just tried it with the MSFFBII - no pitchup at all.
At a stable altitude and 240km/h, actually a very slow slight nose drop if the trimmer's held in, nothing else.
Can you confirm which trimming method you have selected?

Ranma, I just tried all three trimming methods, and can confirm the same results as what you posted. In addition, I tried disabling the 'Pitch Attitude' channel while using the 'Joystick without springs and FFB' method, and the pitch excursions disappeared. It seems to be an issue with that particular trimming method, and the Pitch Attitude hold function of the autopilot.
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Old 10-23-2019, 06:09 PM   #19
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@RANMA
No pretentious "I'm so smart" bullshit going on at all. Also... thanks for suggesting that maybe it's in the way the trimmer mode handles the "trim offset"...

Just like I suggested a few posts before you...

Post #6
"That offset is what I think is causing the movement you're seeing. And... I'm not sure it's a bug. If it is... It may be that the logic behind the FFB mode does the wrong thing with the AP channel's trim offset."

and

"I still feel that the cause is the AP's CURRENT control authority magnitude and how that gets applied to a NEW trimmed state."

Post #10
"If you catch the oscillation (by releasing trim) at a place where some of the 20% control authority in the AP channel is used... Then re-trim... We don't know what the shark's computer (and by that I mean the selected control logic ini the options really...) is doing WITH THAT EXERTED CONTROL AUTHORITY.

We need to."



Quote:
"We're talking about an inconsistent behavior with the trimmer, not the natural oscillations that would occur in not only motorcycles and aircraft, but any moving mechanical device."
No. Only motorcycles and aircraft and maybe a few other unstable yet self righting object. Anything on the ground with more than two wheels specifically does NOT fit in this category.

In any case... It's not my fault you don't understand the concept I'm trying to point out that could be effecting the results we're seeing based on where in that oscillation you're releasing trim. It is a motorcycle or airplane's natural tendency to oscillate back and forth on both sides of an equilibrium. Simply that.

So yeah... get off your high horse. I'm trying to help.




_______________________________________
Anyway... back on topic ...

Yeah...

As I said... I'd like to see a few tests to isolate where the issue is coming from so we can decide if it's a problem with the trimmer mode.. Thanks for those
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Old 10-23-2019, 11:28 PM   #20
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Nobody understands the concept you're trying to point out, hence why we're all ignoring you. Show evidence of what you're talking about, otherwise you're just quoting Wikipedia and yourself.
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