How to set SCAS for hover

[M1Combat]

29 minutes ago, jnr4817 said:

I’ve got the most realistic aircraft controls minus the actual ffb system. I use dampers to act like a pseudo force trim system. All my controls will always stay where I leave them. I haven’t been using the trim button at all. But the scabs system may need it due to programming limitations. I’m not sure. This is the issue. As every person has a different setup. I wish they would specifically discuss those who just Recenter to trim and those who don’t need to Recenter. It’s a huge difference and different way of manipulating the sim flight controls. As my current system Is as realistic as I can get it from the irl aircraft I’ve flown and ridden in. I’m flight med crew full time irl. Eurocopter products but have experience in bell and other manufacturers. 

I don't think it's programming limitations.  The SCAS will need to know what you're asking the controls "center" to be each time you move that center.  That's done by releasing the trim button.  Press the button, move the stick to where you want it, release the trim button.  Just like IRL.  With sticks that re-center you'll then also have to release the stick to let it center but assuming you have the correct options checked in the config of DCS you won't need to do that of course.

 

To note...  It seems that tap-trimming works better in the Apache than the Shark.  I won't go into the details of why you "never" want to tap-trim the shark but suffice to say...  In the Apache it seems to mostly work fine and doesn't cause the same problems it does with the Shark.

[M1Combat]

"I use dampers to act like a pseudo force trim system."

I think I understand the point you're making here but you have to understand that from the perspective of the aircraft...  What your stick does when you let go of it has ZERO to do with trimming. 

It's just where the stick is.

"Trimming" the aircraft is simply telling it to center the current SCAS parameters around where the stick is currently sitting and depending on mode try to hold this or that flight parameter.

The fact that your stick doesn't re-center by itself does not replace the trim system.  You still have to trim just like everyone else does except that you don't need to re-center the controls after releasing trim.

 

[Rogue Trooper]

On 5/3/2022 at 11:33 PM, kgillers3 said:

Retrim 

Retrim Attitude hold or standard up trim?

I think the SCAS in the apache is meant for the pilot to ultimately hold the hover.... SCAS is simply an aid... I think.

At the moment I just manually hold the hover and trim with the standard up trim if need be. It seems easier when watching George's targeting sight on my left MFD.

Seems to be easier this way to also manoeuvre a little left or right to allow George to get LOS in between  a break in the tree line. 

With the Gazelle and a little hard piloting the Tunguska is meat for the grinder!

In the Apache the Tunguska is a serious amount of hard work!  

Edited May 5, 2022 by Rogue Trooper

[Bearfoot]

The manual says that activating the FTR starts to "decay" the SCAS:

Quote

When the force trim release is actioned it causes the SAS command to decay or “washout” at a one second rate. Actioning or “bumping” the force trim release for only a fraction of a second resets the mechanical portion of the force trim to a zero force state, but does not provide enough time to re- center the SAS.

Does this effect the hold modes in any way? E.g., if I have engaged attitude hold < 5 knots, and then I action the FTR for > 3 seconds to recenter the SAS, in DCS at least I remain in position hold. Is that how it's supposed to work? 

[kgillers3]

30 minutes ago, Rogue Trooper said:

Retrim Attitude hold or standard up trim?

 

 

When you hit att you’re not retrimming you’re turning the mode on and off, force trim up or force trim release is what I was referring to, sorry for the miscommunication. 

 

4 minutes ago, Bearfoot said:

The manual says that activating the FTR starts to "decay" the SCAS:

Does this effect the hold modes in any way? E.g., if I have engaged attitude hold < 5 knots, and then I action the FTR for > 3 seconds to recenter the SAS, in DCS at least I remain in position hold. Is that how it's supposed to work? 

Right now there’s no position hold that I’m aware of in game, velocity and attitude hold are in their beginning phases. While you have an indication that the hold mode is active it’s not doing anything for you at those speeds but idk just a guess and they haven’t released anything official yet. 

If you have your control indicator on and you press and hold you can see the green line (sas authority) realign with your control inputs and remain there while force trim is pressed. I bump trim in game, if the sas authority maxes out I press and hold to recenter then back to bump trim. 

[Rogue Trooper]

1 minute ago, kgillers3 said:

When you hit att you’re not retrimming you’re turning the mode on and off, force trim up or force trim release is what I was referring to, sorry for the miscommunication. 

 

Right now there’s no position hold that I’m aware of in game, velocity and attitude hold are in their beginning phases. While you have an indication that the hold mode is active it’s not doing anything for you at those speeds but idk just a guess and they haven’t released anything official yet. 

If you have your control indicator on and you press and hold you can see the green line (sas authority) realign with your control inputs and remain there while force trim is pressed. I bump trim in game, if the sas authority maxes out I press and hold to recenter then back to bump trim. 

Thanks, that is what I used as it seems to have done the job every time. 

For now I have stopped using ATT trim and just prefer the up trim in all flight regimes. seems more fun like that.... If only George was just as enthusiastic!

Although, why have the trim down for disengage ATT and ALT hold, if a second press of ATT disengages ATT mode? Not being disrespectful !

[Bearfoot]

6 minutes ago, kgillers3 said:

When you hit att you’re not retrimming you’re turning the mode on and off, force trim up or force trim release is what I was referring to, sorry for the miscommunication. 

 

Right now there’s no position hold that I’m aware of in game, velocity and attitude hold are in their beginning phases. While you have an indication that the hold mode is active it’s not doing anything for you at those speeds but idk just a guess and they haven’t released anything official yet. 

If you have your control indicator on and you press and hold you can see the green line (sas authority) realign with your control inputs and remain there while force trim is pressed. I bump trim in game, if the sas authority maxes out I press and hold to recenter then back to bump trim. 

Right now there’s no position hold that I’m aware of in game, velocity and attitude hold are in their beginning phases. While you have an indication that the hold mode is active it’s not doing anything for you at those speeds but idk just a guess and they haven’t released anything official yet. 

Really?? Hah. It fooled me. LOL. Placebo effect is strong. I was thinking, look how easy it is to hold a hover with this position subhold ... when it was me all this time

So, whether eventually with the position hold or currently with the other hold submodes, adjusting/interrupting/actioning FTR does not change or disengage the hold mode?

 

[Rogue Trooper]

I think this is a thang with the Apache.

I think the pilot has to do the work and SCAS is simply an aid to make things easier but not perfect.

Perhaps the real Apache boys will sound off here but American Helicopters are not in the same league as European helicopters when it comes to automated flight controls.

Walter J. Boyne's book "how the Helicopter changed modern Warfare" ISBN 9781589807006 is good read but you must read it to the end.

Great book, pave low on the cover.... I mean really... what chopper looks better!

 

[kgillers3]

37 minutes ago, Rogue Trooper said:

 

Although, why have the trim down for disengage ATT and ALT hold, if a second press of ATT disengages ATT mode? Not being disrespectful !

So if you hit ATT or ALT independently it turns on and off independently, down drops both simultaneously, honestly someone somewhere decided that's how they wanted it, it could be just an evolution of design, it was something else but best answer I can give is it is the way it is. 

[Rogue Trooper]

2 minutes ago, kgillers3 said:

So if you hit ATT or ALT independently it turns on and off independently, down drops both simultaneously, honestly someone somewhere decided that's how they wanted it, it could be just an evolution of design, it was something else but best answer I can give is it is the way it is. 

Makes sense, like the Kamov KA-50 AP disengage, all four APS OFF in one go.

Edited May 5, 2022 by Rogue Trooper

[kgillers3]

43 minutes ago, Bearfoot said:

adjusting/interrupting/actioning FTR does not change or disengage the hold mode?

 

So if you think of it this way. You turn on ATT hold and you're going 70kts ground.  It will kick you into Attitude hold, you "talk" to the FMC through the force trim release, so you start walking it back and when it's finally <30 kts ground (decelerating) it will transfer to velocity hold, the entire time you have attitude hold on, it's never changed, but the way you communicate to the fmc is through retrimming via the ftr.  If you are moving the cyclic and not retrimming with attitude or velocity hold it will attempt to reassume it's previously assigned attitude / velocity once you recenter the stick to it's previously trimmed position unless it's beyond the realm of capability at which point it'll drop off. 

3 minutes ago, Rogue Trooper said:

Makes sense, like the Kamov KA-50 AP disengage, all four APS OFF in one go.

 

Yeah, like if you want the altitude hold to drop off because you wanna change altitude you can dump just that off, maybe you're getting ready to do a landing and you want no holds, dump them both. Either way, it's the way they made it at the end of the day. 

That is when altitude hold is included in the game

 

Edited May 5, 2022 by kgillers3

[Bearfoot]

7 minutes ago, kgillers3 said:

So if you think of it this way. You turn on ATT hold and you're going 70kts ground.  It will kick you into Attitude hold, you "talk" to the FMC through the force trim release, so you start walking it back and when it's finally <30 kts ground (decelerating) it will transfer to velocity hold, the entire time you have attitude hold on, it's never changed, but the way you communicate to the fmc is through retrimming via the ftr.  If you are moving the cyclic and not retrimming with attitude or velocity hold it will attempt to reassume it's previously assigned attitude / velocity once you recenter the stick to it's previously trimmed position unless it's beyond the realm of capability at which point it'll drop off. 

So in the above example, you engage ATT hold at 70kts, and then pull the stick back to decelerate, actioning the FTR every now and then to recenter to new reference locations as you slow down? E.g, as you pass through 60, 40, 30 etc. knots (not exactly at those numbers) you would be constantly retrimming to the new speed, all the while the hold mode on?

[kgillers3]

3 minutes ago, Bearfoot said:

So in the above example, you engage ATT hold at 70kts, and then pull the stick back to decelerate, actioning the FTR every now and then to recenter to new reference locations as you slow down? E.g, as you pass through 60, 40, 30 etc. knots (not exactly at those numbers) you would be constantly retrimming to the new speed, all the while the hold mode on?

You can re trim once, point is you're telling the fmc what you want it to do via the ftr and the trimmed position 

not neccessarily important if you're not using hold modes

Edited May 5, 2022 by kgillers3

[Bearfoot]

Thanks! Appreciate the insight. Things are beginning to become slightly less fuzzy!

So we use the FTR to update the FMC what the reference is regardless of the hold mode, but the hold mode determines what gets "held" with respect to the reference. 

As you come in for a hover then, would you typically engage the hold mode while at speed and then action the FTR as you slow down to 5 knots? Or just engage the hold mode after stabilized in a hover (and then maybe use the FTR to sweeten or fine tune the hover/heading etc)?

 

[Rogue Trooper]

How do they do it in real life?

I just find it easier to disengage all SCAS systems to pull into a low level hovering fire position, only using the forward trim. then re-engage (if I decide to use it) the ATT trim.

The altitude trim will be GOD almighty when it arrives! My God altitude is twitchy when a missile leaves the rack.... Altitude requires constant attention! Drift to left or right is fine though.

The left MFD is just weapons and CPG targeting image for me.... how will I drift with the next shot and does George have LOS! 

Edited May 5, 2022 by Rogue Trooper

[kgillers3]

6 minutes ago, Bearfoot said:

 

As you come in for a hover then, would you typically engage the hold mode while at speed and then action the FTR as you slow down to 5 knots? Or just engage the hold mode after stabilized in a hover (and then maybe use the FTR to sweeten or fine tune the hover/heading etc)?

 

That would be a personal preference based on what you're comfortable with. 

4 minutes ago, Rogue Trooper said:

How do they do it in real life?

I just find it easier to disengage all SCAS systems to pull into a low level hovering fire position, only using the forward trim. then re-engage (if I decide to use it) the ATT trim.

The altitude trim will be GOD almighty when it arrives! My God altitude is twitchy when a missile leaves the rack.... Altitude requires constant attention! Drift to left or right is fine though.

The left MFD is just weapons and CPG targeting image for me.... how will I drift with the next shot and does George have LOS! 

 

Regardless of what happens in RL, you'll find a way that makes it most comfortable for you and your setup. 

Edited May 5, 2022 by kgillers3

[jnr4817]

5 hours ago, M1Combat said:

"I use dampers to act like a pseudo force trim system."

I think I understand the point you're making here but you have to understand that from the perspective of the aircraft...  What your stick does when you let go of it has ZERO to do with trimming. 

It's just where the stick is.

"Trimming" the aircraft is simply telling it to center the current SCAS parameters around where the stick is currently sitting and depending on mode try to hold this or that flight parameter.

The fact that your stick doesn't re-center by itself does not replace the trim system.  You still have to trim just like everyone else does except that you don't need to re-center the controls after releasing trim.

 

Totally agree with all this. The latest update has been better. Im a trim tapper and don’t hold it, when I use it. I’ll try using it more and see if it does anything different. Im a pretty stable flyer in the 64 already. 

[M1Combat]

If you don't retrim every time you stop moving the stick (especially if it's outside the SCAS boundary) then you're fighting the system.  It's designed to be trimmed.  In sim and IRL.

[Raptor9]

To clarify a few terms and their correct usage to avoid confusion...there is only one "Trim" command, and that is pressing the Force Trim Release button.  So any time someone mentions "re-trim" or "interrupt the force trim", it means pressing this 4-way Force Trim/Hold Mode switch to the 12 o'clock.  So there isn't really a "trim up", "trim left", "trim right" or "trim down" command in the Apache, it's simply a four-way switch where one direction is the Force Trim Release, and the other three are Hold mode commands.  I say this to prevent confusion with those coming from fixed wing modules or the Mi-24 Hind where they expect the trim control to behave like a 4-way hat with 4x different trim directions.

Not to be confused with "put the aircraft into aerodynamic trim"/"NOE trim"/"nose-to-tail trim".  These are referring to the alignment of the fuselage with regards to the airflow and/or flight direction, based on the skid/slip indicator, which is also called the "trim ball".

2 hours ago, Bearfoot said:

So we use the FTR to update the FMC what the reference is regardless of the hold mode, but the hold mode determines what gets "held" with respect to the reference.

Yep, so if I am in a level flight attitude with Attitude hold engaged and I interrupt the force trim, put the aircraft into a 10 degree banking turn, and then let go of the force trim, the aircraft will attempt to maintain that 10 degree banking turn.

If I am flying forward at 30 knots ground speed in Velocity Hold, interrupt the force trim, decelerate to 25 knots ground speed, and then let go of the force trim, it will now attempt to maintain 25 knots ground speed.

If I decelerate below 5 knots ground speed, it should automatically switch to Position hold even without touching the FTR switch; but if I am decelerating to a hover, I'm typically going to interrupt the force trim anyway while I maneuver the aircraft, and then once set I'll let go of the FTR and the aircraft will establish that position as the reference point to hover over. If I want to reposition to another hover location, I interrupt the force trim, re-position, and then let go of the FTR switch and the aircraft will hover at that new reference position.

Unlike the Ka-50, there are specific breakout values that the hold modes will stop fighting the pilot inputs because the FMC recognizes these are deliberate inputs, and will not reestablish new references until back within certain criteria. This is done independently of the force trim usage to allow the pilot to fly through the hold modes without needing to disengage them first.

The AH-64D FMC shouldn't be fighting the pilot inputs outside of its rate damping SAS function, but at the risk of sounding like a broken record, it is all work in progress.

Edited May 5, 2022 by Raptor9

[Rogue Trooper]

Trim up is the one... yes all other trims seemed that way with experimentation!

 

 

Edited May 5, 2022 by Rogue Trooper

[Bearfoot]

1 hour ago, Raptor9 said:

To clarify a few terms and their correct usage to avoid confusion...there is only one "Trim" command, and that is pressing the Force Trim Release button.  So any time someone mentions "re-trim" or "interrupt the force trim", it means pressing this 4-way Force Trim/Hold Mode switch to the 12 o'clock.  So there isn't really a "trim up", "trim left", "trim right" or "trim down" command in the Apache, it's simply a four-way switch where one direction is the Force Trim Release, and the other three are Hold mode commands.  I say this to prevent confusion with those coming from fixed wing modules or the Mi-24 Hind where they expect the trim control to behave like a 4-way hat with 4x different trim directions.

Not to be confused with "put the aircraft into aerodynamic trim"/"NOE trim"/"nose-to-tail trim".  These are referring to the alignment of the fuselage with regards to the airflow and/or flight direction, based on the skid/slip indicator, which is also called the "trim ball".

Yep, so if I am in a level flight attitude with Attitude hold engaged and I interrupt the force trim, put the aircraft into a 10 degree banking turn, and then let go of the force trim, the aircraft will attempt to maintain that 10 degree banking turn.

If I am flying forward at 30 knots ground speed in Velocity Hold, interrupt the force trim, decelerate to 25 knots ground speed, and then let go of the force trim, it will now attempt to maintain 25 knots ground speed.

If I decelerate below 5 knots ground speed, it should automatically switch to Position hold even without touching the FTR switch; but if I am decelerating to a hover, I'm typically going to interrupt the force trim anyway while I maneuver the aircraft, and then once set I'll let go of the FTR and the aircraft will establish that position as the reference point to hover over. If I want to reposition to another hover location, I interrupt the force trim, re-position, and then let go of the FTR switch and the aircraft will hover at that new reference position.

Unlike the Ka-50, there are specific breakout values that the hold modes will stop fighting the pilot inputs because the FMC recognizes these are deliberate inputs, and will not reestablish new references until back within certain criteria. This is done independently of the force trim usage to allow the pilot to fly through the hold modes without needing to disengage them first.

The AH-64D FMC shouldn't be fighting the pilot inputs outside of its rate damping SAS function, but at the risk of sounding like a broken record, it is all work in progress.

 

Thanks Raptor9 -- these examples really help pull it together! 

[dburne]

I have been using ATT Hold in a Hover whilst I employ my Hellfires at the weapons ranges during my learning phase. Seems to do pretty well for me, when done I just disengage and off I go to use rockets and guns. Sometimes I am moving really slowly when I engage it and it maintains that as well. I find I can yaw the chopper to my left and right if needed during this hold, if I give enough rudder it will take on and point to the new direction and continue to maintain the hold.

Edited May 6, 2022 by dburne

[Floyd1212]

In these two hypothetical scenarios, how does the SCAS system behave?

1) If I never touch the trim during a flight at all, is the system "fighting" me, or I have I not even invoked the SCAS to try and assist me since I haven't pressed the trim release button at all?

2) If I press-and-hold the trim release button as soon as I get in the helo (let's say I bind it to a toggle switch on my throttle and flip it on and leave it on) and then fly the helo around, is this the most "pure" way to interact with the helo and work "with" the SCAS?

Will the helo behave differently, from a stability standpoint, in these two scenarios?

[Raptor9]

On 5/5/2022 at 10:10 PM, Floyd1212 said:

In these two hypothetical scenarios, how does the SCAS system behave?

Will the helo behave differently, from a stability standpoint, in these two scenarios?

Currently, when you press the force trim release, it removes SAS functionality altogether and re-centers the SAS authority within each flight control servo.  This means that pressing and holding the force trim release is the same as disengaging the FMC axes altogether.

How it should work is that regardless of the force trim release being pressed or not, it should provide command augmentation (CAS) in pitch, roll and yaw axes to provide uniform control response across all longitudinal airspeeds. In addition, with the force trim release not pressed, it should provide an additional SAS function called "atmospheric upsetting prevention" which helps minimize effects from things like turbulence.

Add onto that the additional logic of the Heading hold (<40 knots) and Turn Coordination (>40 knots), which is a separate collection of logics as well.  The most basic of which is that pressing the force trim release removes any heading hold logic from being applied.

So to answer your question (in the current build of the DCS AH-64D) the SAS will still be active in your first scenario, as will the heading hold under certain conditions that "capture" the heading at speeds below 40 knots. In your second scenario, you will essentially be flying around with the SAS disabled when the FTR is being pressed continuously.

The bottom line is that the SCAS is still a WIP, so the question of how the SAS system behaves is a tricky one depending on whether you mean how the DCS AH-64D SCAS system is currently behaving versus how it should be behaving (and how it will hopefully behave in the future later in Early Access).  The real AH-64 is a little "squirrely" without the Flight Management Computer engaged, so the FMC's SCAS functions make the aircraft a stable and predictable aircraft.

[M1Combat]

Thank you Raptor