DCS: AH-64D Flight Model discussion

[Mad_Shell]

1 hour ago, NineLine said:

1) no changes to the core flight model, just some updates to how the collective channel behaves

Mmmmh, according to quaggles website quite a few parameters in the fligt model have been changed (https://github.com/Quaggles/dcs-lua-datamine/commit/cf37c477acf7370f0247867a1d7b71e7ba9609c7#diff-61004a5997f6aa0641f2e2225af9ea2c0d86d70f556ac5b672ebef28c3220bffR855)
Even the center of mass of the aircraft has been shifted.

[M1Combat]

1 hour ago, Raven434th said:

it seems every patch of late changes the way that calibration behaves

That sounds a lot like progress :)...  Keep up sir...

1 minute ago, Mad_Shell said:

Even the center of mass of the aircraft has been shifted.

Well...  That's not "the flight model"...  just a referenced data point the flight model uses.  And the thing that caused that change is in the patch notes right?

[Mad_Shell]

3 minutes ago, M1Combat said:

That sounds a lot like progress :)...  Keep up sir...

Well...  That's not "the flight model"...  just a referenced data point the flight model uses.  And the thing that caused that change is in the patch notes right?

you're playing with words here... Even if the underlying model and equations haven't changed, when you modify parameters such as center of mass position, rotor gyroscopic moment, rotor dampening coefficient, main rotor stiffness, and more, you are effectively changing how the aircraft reacts to inputs.

[M1Combat]

Agreed.  So the right terms might be "You've changed things that make it fly differently" or even "You've changed things that cause the aircraft to react differently to control input".

 

I'm not trying to be a hard ass here...  I'm just saying that the ED employees likely have a somewhat more nuanced approach to what they include when discussing "the flight model" than some of us why just fly the things.  Because they and we operate from a slightly different perspective...  we should all be willing to look at the subject with that in mind..  Them and us :).

 

So yes...  I also think Nine could probably have replied "We changed some parameters"...  If he even knew LOL...

 

Edited April 13, 2023 by M1Combat

[Raptor9]

3 minutes ago, Mad_Shell said:

Mmmmh, according to quaggles website quite a few parameters in the fligt model have been changed
Even the center of mass of the aircraft has been shifted.

With the exception of the center-of-mass, those parameters are regarding the FMC's Collective channel, not the core flight model. And the center-of-mass adjustment was very small, not significant enough to alter the handling of the helicopter. I know this because I do flight model comparisons all the time across multiple DCS installs.

I think what is happening here is some people are using inaccurate terms to describe what they are seeing.

"Flight Model" = the core behavior of the aircraft itself, excluding behaviors exhibited by the FMC's SCAS and/or hold mode logic.
"SCAS" = the behavior of the FMC's logic in affecting the flight control servos such as damping effects, turn coordination, etc.
"Hold modes" = the assistance provided by the FMC to allow limited hands-off flying.

If people are saying "Flight model" to describe all three aspects, then they are technically "correct" in stating something has changed, but they are incorrect in stating what has been changed. The SCAS and hold mode behavior was indeed modified in the recent update (as was listed in the changelog), as well as almost every recent update in the past several months (with the exception of January I believe). If a player relies on the hold modes to keep their aircraft under control in a hover, then yes, they may interpret changes within these logics as changes to the "Flight model", but this is not the case.

If you were to fly the DCS AH-64D without hold modes in the Stable version of DCS World from December, and then fly the Open Beta version, the behavior is identical when performing a hover (Assuming the control profiles, environmental conditions within the mission, and the physical configuration of the aircraft with regards to fuel and weapons load are EXACTLY the same). The changes you would see is the Collective channel behavior as you started performing forward flight with changes to the collective input. I've done this comparison myself today.

People tend to see what they want to see, and no amount of clarification from myself or other members of ED will likely change anyone's assessment, but if someone is saying "Flight Model" to describe the SCAS/hold mode changes, that is like saying the F/A-18 flight model changed after an adjustment to the Autopilot.

[NineLine]

Don't believe me, but believe the really real Apache guy above

[admiki]

In hover, for me,  seems to be more sensitive to collective inputs and is also more twitchy in regard to pedals inputs. I don't know if it's me, but it also seems to want a lot more trim release pressing and more small cyclic inputs to get it to really stay in one spot. Sort of how Huey requires cyclic inputs to keep in one spot, but without Huey wobble.

OTH, it's a lot less prone to lose altitude when you do slow deceleration and go through 40-ish knots.

Anyway, I would under no circumstances call it a "hot mess". Yes, it takes some muscle memory adjustment to it, but 10-15 minutes should do it.

[pii]

2 hours ago, Amarok_73 said:

Christmas (before rather than after), when it was totally possible to get into stable, hands free hover on stabilizers and fly stable forward with stabilization enabled on both, altitude and attitude. Then next patch ruined it.

Exactly my experience.

I thought, and maybe I'm wrong but, when developing software you don't release the new code until it fixes or makes better the old code it is replacing. Maybe it's just me?

[Raptor9]

I would like to ask two open-ended questions to anyone:

1) When flying with Attitude Hold enabled (regardless of sub-mode), how many use the force trim?
2) When flying without Attitude Hold enabled, how many use the force trim?

[M1Combat]

23 minutes ago, pii said:

Exactly my experience.

I thought, and maybe I'm wrong but, when developing software you don't release the new code until it fixes or makes better the old code it is replacing. Maybe it's just me?

 

Well...  That's a pretty "This is a released product and we better not eff it up" approach... to put it nicely.

 

IMO...  If they find something that's modeled wrong or has wrong parameters they should strongly consider fixing it even if it affects other things in a negative way.  The reason for that is simply because "early access...  so deal with it..." as well as the simple fact that there could be ways they need it tested by the open beta team (damn near everyone I think...  It's an opt in situation so if you're there it's your fault) so they can gather data about how it's affecting people that aren't gradually being introduced to the changes.  Maybe they need to throw it all in one package for the open beta testers because the closed beta testers become used to the model as it gradually changed so now they're blind to the culmination of the total package of changes.  Or...  maybe it's an integral tested part of a bigger change and that change is important to push to the open beta testers so they run with it.  Also...  maybe keeping it "feeling nicer" masks issues in other parts of the model that they need to have corrected, but they aren't finding them because they've masked it by incorrectly tuning some other part.

 

Either way... Be nice.

Edited April 13, 2023 by M1Combat

[pii]

3 minutes ago, M1Combat said:

The reason for that is simply because "early access...  so deal with it..." as well as the simple fact that there could be ways they need it tested by the open beta team

I have been dealing with it, thank you, but if you think I'm going to remain silent for, at least, the next three years because it's EA you are sadly mistaken.

[M1Combat]

I didn't ask you to remain silent sir :).  I asked you to be nice, and it was simply asked because the world needs more nice and less rude.

Your post was clearly an obvious jab at what you think was a release that shouldn't have happened because it made something subjectively worse for you and it was also made from a "high horse" as it were.  It's fine to see it that way...  that's not a problem...  but some snide comment about it doesn't change the fact, doesn't help anyone and only serves to add to negativity.

 

So be nice ;).  Please :).

[Floyd1212]

I think the answer is: fly more and you will get used to it.

All of the changes that have been made over time have ultimately been for the better.  Yes, there is some short-term "this feels different" condition when a change is made, but keep flying and it will become the new normal.

I personally haven't felt huge differences between patches.  Yeah, when they messed with the tail rotor a while back, it took some adjusting, but after a couple flights your muscle memory is reset.  If you are flying other stuff and coming back to the Apache every now and then, give it some time to settle back in.

[Floyd1212]

2 hours ago, Raptor9 said:

I would like to ask two open-ended questions to anyone:

1) When flying with Attitude Hold enabled (regardless of sub-mode), how many use the force trim?
2) When flying without Attitude Hold enabled, how many use the force trim?

I only use Attitude Hold when in a hover.  When in fwd flight I just trim to maintain my attitude.

I use trim to reduce the workload when cruising, but when flying NoE or when coming in to land, I reset trim and don't set it again unless I want to take my hands off the stick, or establish a hover.

When I do trim, I use the tap method (center trim mode).  I would try the hold method more, but the hat I use on my Warthog is way to stiff to keep it pressed long-term.

[al531246]

Just want to add my 2 cents to this. Since today's update (2.8.4.38947) the Apache FM is acting up. Very twitchy. Extreme roll tendencies - the helicopter is entering barrel rolls from relatively tame maneuvers. 

When I turn the SAS off most of these issues cease. I do believe the values for the SAS are incorrectly tuned. If it's anything like a PID it's quite apparent your 'P', or more likely 'I' values are too high. Those were my impressions of the SAS prior to this update, it's worse now. 

[Amarok_73]

5 hours ago, Raptor9 said:

I would like to ask two open-ended questions to anyone:

1) When flying with Attitude Hold enabled (regardless of sub-mode), how many use the force trim?
2) When flying without Attitude Hold enabled, how many use the force trim?

As I am flying with FFB joystick, for me, answer on both questions is positive.

[Amarok_73]

4 hours ago, Floyd1212 said:

I think the answer is: fly more and you will get used to it.

All of the changes that have been made over time have ultimately been for the better.  Yes, there is some short-term "this feels different" condition when a change is made, but keep flying and it will become the new normal.

I fly this machine a lot, like every day, few hours, and still I can't get used to it having in minds that there was already pretty good implementation of stabilisation. I remember that at that time, the only significant issue with the FM was, that in the stable straight flight, the helicopter could turn suddenly in strange directions, just as when hovering it could suddenly (with a stronger gust of wind) twist and lose stability.platform. And the patch that repaired above, the same moment destroyed the attitude and alitude stabilisation in hover and straight flight.

[Toge]

2 hours ago, al531246 said:

Just want to add my 2 cents to this. Since today's update (2.8.4.38947) the Apache FM is acting up. Very twitchy. Extreme roll tendencies - the helicopter is entering barrel rolls from relatively tame maneuvers. 

Exactly this. I don't know what happens internally at ED (communication issues or something?), and don't really care about semantics regarding what is "core flight model" etc, but in my experience the apache handles very differently now. Rolling a lot more than before, especially when lowering collective, so maybe it's due to the collective changes, maybe not.

I'm not saying it's bad - if it's closer to the real thing, that's awesome. If there was some unintended change, that's fine too, it's WIP and will change in the future probably many times still, and we'll all anyway get used to flying it again. I still love it and you for developing it, and I'm happy to see all updates and improvements.

But ED, please don't disregard and ignore people's feedback with a simple "nothing changed" when it's really obvious to us that something changed that has an effect on how it flies.

[ams999]

For me, the Apache now enters an endless right turn barrel roll when I reduce the collective to zero during straight flight. Is this correct? The Huey simply takes the nose down, which I would have expected with the Apache, too.

[admiki]

7 hours ago, Raptor9 said:

I would like to ask two open-ended questions to anyone:

1) When flying with Attitude Hold enabled (regardless of sub-mode), how many use the force trim?
2) When flying without Attitude Hold enabled, how many use the force trim?

I see where you are going with this, but problem is that majority of fliers use center trim due to hardware they have. Makes precise trimming a bit hard.

All my controls stay in place, so makes it a lot easier.

Answers on both questions are: all the time, either beeping it or holding until in stabilized new position.

[Raptor9]

2 hours ago, Toge said:

I don't know what happens internally at ED (communication issues or something?), and don't really care about semantics regarding what is "core flight model" etc,

But ED, please don't disregard and ignore people's feedback with a simple "nothing changed" when it's really obvious to us that something changed that has an effect on how it flies.

It is more than just semantics. If a player simply says "Something is broke." in a bug report, that gives us zero information to go on. If a player says the "(insert function) isn't working as it should." we are going to assume they mean that specific function. Words and terms do matter, since we have no way of determining what a player actually means in lieu of actual data such as track files and such.

If I tell a restaurant their steak isn't cooked enough, but I really meant their hamburgers, that doesn't convey the proper feedback for the appropriate corrections to be made.

2 hours ago, admiki said:

I see where you are going with this, but problem is that majority of fliers use center trim due to hardware they have. Makes precise trimming a bit hard.

No, I don't think you do. I'm trying to ascertain the root cause of what people are describing as "broke" or "not behaving as it should." because I have zero data to go on. But I'm asking these questions in an open-ended way so as to not imply leading answers. Assumptions and innuendo is not useful when diagnosing the root causes. The issue isn't the trimming mode used in the special optioms, it is the overall strategy of when the force trim is being interacted with altogether that I am trying to determine.

[Toge]

11 minutes ago, Raptor9 said:

It is more than just semantics. If a player simply says "Something is broke." in a bug report, that gives us zero information to go on. If a player says the "(insert function) isn't working as it should." we are going to assume they mean that specific function. Words and terms do matter, since we have no way of determining what a player actually means in lieu of actual data such as track files and such.

If I tell a restaurant their steak isn't cooked enough, but I really meant their hamburgers, that doesn't convey the proper feedback for the appropriate corrections to be made.

I see, and agree with you there. My point was more to the direction that if players give feedback that the thing flies/behaves weirdly, there might be a reason worth investigating even if the player can't give exact technical details or know how you differentiate what is flight model and what is not internally, instead of just falling back to "no changes were made to this specific part of the whole". And even if the player specifies some technical name of a system, you have to understand that we don't necessarily know what we're talking about or what it means to you in a technical sense. Following your example, a customer in a restaurant might generally complain that the taste of their favorite dish has changed, instead of being specific about which part or the way it was cooked, and then it would be the cook's job to figure out if they really changed something and if it's for the best, perhaps by asking the customer for more details if needed.

And yes, working in software dev with customers myself, I perfectly understand that "this feels more twitchy and erratic" is not something that you can really work with. And I see you're already asking those more specific questions to get to the root of it, so kudos to you for being patient and trying to figure it out. The first reply by NineLine to the comments about the latest patch seemed more dismissive to me, and that's where my reaction comes from.

To answer your questions, I don't really use the holds almost ever (but if I do, I try to trim as perfect as I can before engaging them), and mainly use the trim for level flight only. During combat maneuvers I generally don't touch the trim at all.

[Renko]

12 hours ago, Raptor9 said:

I would like to ask two open-ended questions to anyone:

1) When flying with Attitude Hold enabled (regardless of sub-mode), how many use the force trim?
2) When flying without Attitude Hold enabled, how many use the force trim?

For me is a no for the Attitude Hold, but yes for Force Trim.
I can mantaining attitude in hover pretty well without much effort most of the time, or while flying

My setup is (because i think is important in this discussion):
- In special option i have Instant trim for cyclic, and no trim for peddals (peddals without trim springs and FBB)
-CM3 base with 10mm stick extension
-Warthog throttle
-VKB T-Rudder peddals

Tested always in Instant Action, Caucasus, Mission "AH-64D Runway Start"

It did felt more sensitive last night. Today felt better, but i have a more agresive curve on cyclic axis in the Apache than any other helo in DCS. So it is more sensitive in some degree.

But while testing i did notice something that changed, and that may add to the twitchy feeling.
In the pedals it feels like the Heading Hold mode has more authority now. And it needs more input to move it. And when it kicks in its harder, making it wobble on the yaw
For example, when you take off as soon as you are light on wheels it kicks in .
Then as soon as you are on the air, suddenly it makes an input to the left. No matter if your rudder has no input, or if you are pressing it to the left/right.
That didnt happened  in the previous version 2.8.3.38090
Look at the image named Screenshots A. I tried to not make any inputs. Just collective
Disregard this avobe because without Force Trim the FMC was struggling to correct that. My Bad, it was not a good example. Sorry


And while you are hovering, using hold modes to achive a stable position, i noticed something too with the FMC cyclic channel.
In the DCS 2.8.3.38090 Open Beta when you are stable, the Green cross from the FMC cyclic channel is outside the center.
While in the current version is centered
In the Screenshots B the most modern version is the one with the blue boxes


I dont know if this adds to the discussion, but i found those changes on the behaviour of the Apache that may change the user experience.
Hope it helps

Edited April 14, 2023 by Renko

[placsea]

On 4/14/2023 at 9:38 AM, Raptor9 said:

I would like to ask two open-ended questions to anyone:

1) When flying with Attitude Hold enabled (regardless of sub-mode), how many use the force trim?
2) When flying without Attitude Hold enabled, how many use the force trim?

Edit: I was wrong. No problem or issue. 

Edited April 15, 2023 by placsea

[admiki]

9 minutes ago, placsea said:

So the latest patch has fixed the collective and the altitude hold mode seems much more reliable and steady, am I doing anything wrong to induce the attitude hold drift or is it just a w.i.p thing? 

I see only altitude hold drift here?

Which makes sense. If you look at collective channel, you can see FMC increasing collective until it runs out of authority. Reason that is happening is your helicopter increasing speed. Increasing speed will decrease lift.