How do real apache pilots deal with the SCAS?

[Hiob]

1 hour ago, PHMAC said:

I don’t think the ‘Instant Trim’ and ‘Centre Joystick Trim’ options are meant for self centering joysticks with springs.

 

Yes, they are. 

The difference is. With the first option the trim will instantly take effect which may cause a jump in the controls if you are not quick enough. The second option will disregard any movement of the physical stick before you recentered it.

The latter worked perfectly for ages in the Hip, because they hadn't any fade in on the instant trim. I think they improved that for the Apache. Now both basically work (for me). 

Edited June 15, 2023 by Hiob

[PHMAC]

10 hours ago, Hiob said:

The latter worked perfectly for ages in the Hip, because they hadn't any fade in on the instant trim. I think they improved that for the Apache. Now both basically work (for me). 

 

I guess you would need to have some kind of center detent to know exactly where to place your joystick after trim…and you need to be very quick to avoid the control jump.

 

11 hours ago, corbu1 said:

I use a modified stick to stay in place where I leave it and doesn’t self center.

Therefore I use the trim option „Joystick without springs and FFB“ which works nice for me.

That’s what I have as well. And the ‘Joystick without springs and FFB’ works very nice.

Do you use the Force Trim release button every time you reposition your stick?

Because I think it’s benefit/ impact is quite limited with our setup.

Edited June 16, 2023 by PHMAC

[TZeer]

Quote

 

Do you use the Force Trim release button every time you reposition your stick?

Because I think it’s benefit/ impact is quite limited with our setup.

 

I have same type of setup, and I mostly trim when moving the stick.

Reason is to have the flightcontrolsystem work WITH you and not AGAINST you.

If you don't trim, there is a bigger possibility that your system will get saturated. Specially on the tailrotor.
Small corrections it's not always necessary. But I trim when picking up speed, slowing down to hover, doing turns etc. 

Doing this I always give the system the best possible conditions to "assist" me.

Edited June 16, 2023 by TZeer

[corbu1]

vor 23 Minuten schrieb PHMAC:

 

That’s what I have as well. And the ‘Joystick without springs and FFB’ works very nice.

Do you use the Force Trim release button every time you reposition your stick?

Because I think it’s benefit/ impact is quite limited with our setup.

I use it as often as possible. Small tabs after small cyclic corrections. when bigger cyclic movements I press and hold FTR until I reached new heading and attitude, then release FTR. At least I try to hold FTR pressed for at least 3-5 seconds.

vor 12 Minuten schrieb TZeer:

I have same type of setup, and I mostly trim when moving the stick.

Reason is to have the flightcontrolsystem work WITH you and not AGAINST you.

If you don't trim, there is a bigger possibility that your system will get saturated. Specially on the tailrotor.
Small corrections it's not always necessary. But I trim when picking up speed, slowing down to hover, doing turns etc. 

Doing this I always give the system the best possible conditions to "assist" me.

 

This is why I press and hold FTR for 5 seconds.

[PHMAC]

Thanks @corbu1and @TZeer…that’s what I needed to know. 
 

[skypickle]

On 6/12/2023 at 1:00 PM, Raptor9 said:

Force trim overshoot is possible in any helicopter that has a force trim system with a force gradient, it is not a product of SCAS but the very fact that you are applying a muscular force against a resistance that is suddenly removed. Have a friend hold up their hand against yours to apply resistance as you try to move it. Tell them to stop resisting against your pressure and then try to keep your hand at its precise location without moving it when they simply stop resisting. Unless your timing is absolutely perfect, your hand will overshoot its position.

It may not manifest the same way in the UH-1 due to the different rotor system and relative responsiveness to control inputs compared to the AH-64.

That's how I would do it in real-life. However in DCS, I may let go of the FTR a few times during a deceleration to a hover, simply to regain some aft authority of my physical stick on my desk. I don't have a force-feedback stick so as I progressively accelerate forward in the DCS AH-64D (or any helo in DCS), I will intermittently let go of the force trim and let it spring back to center and resume my acceleration. When decelerating I do the same thing but in reverse.

@Raptor9i find a significant difference in dcs between force trim release in the huey and the apache. Because the scas actively alters control inputs, when ftr is depressed in the apache the sudden absence of those inputs can lead to wild changes in attitude. This is not force trim release overshoot due to the pilot’s hand accidentally moving after resistance is released because my hand does not move when i depress ftr. The force feedback stick i use provides a clear and significant resistive force but it is not a lot. I can continue to fly the bird w fingertip control at all times. However ed may have modeled and simulated this behavior so when ftr is depressed this wild behavior happens even though there is no stick movement.

[Raptor9]

1 hour ago, skypickle said:

@Raptor9i find a significant difference in dcs between force trim release in the huey and the apache.

The original conversation you started was about how real AH-64 pilots deal with SCAS, and you described your experiences interacting with it and how/when you use the force trim. In my initial response I was explaining the real-world reasons why the force trim is usually held down when initiating cyclic or pedal movement (instead of simply tapping it when reaching a new position) and why these substantial differences in control inputs that players see in DCS don't manifest in real life.

Following my response, you made the following statement:

On 6/12/2023 at 11:02 AM, skypickle said:

Still i never experience force trim overshoot in the huey prob because there is no scas. It just has the magnetic forces hold the stick in place. 

This statement was not correct in that force trim overshoot is purely a result of a force gradient provided by the force trim system. SCAS has nothing to do with it. You can experience force trim overshoot in any helicopter that has a force trim system with a force gradient, regardless of whether it has any sort of stability assistance system like the AH-64's SCAS (and I have).

My original statement was not an explanation of how anything functions in DCS, it was an explanation of why the force trim is used the way it is in the real AH-64, as well as many other real-life helicopters. However, the broader point I was making is that many players find the AH-64's SCAS system un-intuitive because they are not using the force trim system as intended; and if they had the same physical hardware that exists in the real AH-64 cockpit, it would be very apparent why that is.

If the SAS sleeves within the flight control servos are offset within their respective authorities, when the force trim is pressed these SAS sleeves return to center. This requires that the physical controls be adjusted to maintain the current attitude. However, if the force trim had been depressed before any substantial control inputs were made and then released when those inputs had stopped, the SAS sleeves would already be very close to center so that when the force trim is pressed the next time, there will not be substantial SAS sleeve travel because the SAS sleeves will rarely be very far from center. (This is why I stated in my original response that it is rare to encounter SAS SATURATED if the force trim is used correctly)

So to reiterate my point, force trim overshoot is not the cause of the DCS AH-64 to incur a significant deviation from its attitude when the force trim is depressed. The cause of this is improper use of the force trim release itself, which is why you hear Bradmick or myself encouraging players to stop ignoring the force trim when making adjustments to the flight controls. The very fact that players are not experiencing force trim overshoot when their physical hardware does not simulate the same force gradient of the real force trim system leads to many of these misconceptions as to the role that the FTR switch plays in controlling the helicopter and interacting with the SCAS system; which is why these effects do not occur in the DCS Huey since it doesn't have a SCAS system.

Force trim and SCAS are two separate systems, but the Force Trim Release switch position interacts with both systems at the same time. Therefore if you are improperly using the FTR switch due to a misconception of how it is used in real-life (which is the reason for my original comments about force trim overshoot), this will lead to a misconception of how the SCAS should work in conjunction with the pilot's desired control inputs.

[bradmick]

Bottom line. Regardless of hardware, push the dang button. Either put an input in and then push the button (and perform appropriate stick recenter it procedures based on special options selections) or push the button, make the input, release the button (and perform appropriate stick recenter procedures based on special options selections).

Yes, with the hold modes OFF you can “bump” the force trim, I.e. performs short press after making a micro adjustment of the controls, this will not lead to a SAS saturate (except for heading, depending on conditions, wind direction and magnitude) because you haven’t commanded the holds to hold anything.

Once you bring the hold modes on, you need to press and hold, fly to the desired state, and then release the force trim button.

The reason you have to do this with the hold modes on is because you need to center the SAS so it has its full authority when you let go of the force trim switch at the desired flight control position. The force trim button updates the FMC and the hold modes when they’re on what they should hold.

There are no more words in the English language to explain this. This is how it works, this is the logic and interaction required regardless of if you have a stick that centers or a stick that stays in a position on its own. Push, the dang, button.

[Floyd1212]

I recently made a tweak that helped my situation with holding the FTR for longer periods.  Since I have the FTR mapped to a rather stiff TMS hat on my Warthog stick, holding it was a problem and I would find my finger had relaxed enough to let go of FTR and then axis inputs on my stick were ignored until I re-centered it.

Using Joystick Gremlin, I set it up so I could quickly tap up on the hat to toggle FTR on and off (basically telling JG to hold the button down for me), but if I held the hat up for more than 0.25 seconds, FTR would work as intended, lifting the button when I let go of the hat.

It took a couple mistakes after I made the change for it to sink in, but now I have adjusted, and it is working well.

[TZeer]

I have made a secondary FTR button on my collective to deal with the same problem as @Floyd1212 mentioned. I use my pinky button on my collective. 
It's also much easier to do really fine adjustments to my cyclic when I don't have to keep holding a button on the same cyclic, specially when going from forward to hover, or turning the Apache while in hover. 

I'm just waiting for some parts so I can lower my cyclic down, this way I can rest my arm om my thigh, and get proper support for my arm. Should make it much more comfortable holding FTR while flying, and prevent unwanted cyclic inputs.

Edited June 16, 2023 by TZeer

[corbu1]

vor 3 Stunden schrieb TZeer:

I'm just waiting for some parts so I can lower my cyclic down, this way I can rest my arm om my thigh, and get proper support for my arm. Should make it much more comfortable holding FTR while flying, and prevent unwanted cyclic inputs.

The extension I use for my cyclic (TM warthog stick) was originally about 45cm in length. I shortened it a few cm‘s so I can rest my arm on my thigh, which is very helpful for fine precision movements. I find it also much more relaxing for my arm.

Edited June 16, 2023 by corbu1

[Hiob]

17 hours ago, bradmick said:

Bottom line. <…> ….push the dang button. 

perfect summary!

[JCae2798]

As a clutch user, this system really bothers me.  I've read a lot on the trim system and this thread but continue to be unsure and frustrated how it works.  Why can't we just have an option to disable this so that we don't have to worry about a trim system?  Could this not be an option?

Edited June 18, 2023 by JCae2798

[Raptor9]

15 minutes ago, JCae2798 said:

I've read a lot on the trim system and this thread but continue to be unsure and frustrated how it works.

Many players are making this out to be more complicated than it is. It is actually quite simple: "Press the switch, move the controls, let go of the switch". No more to it than that.

15 minutes ago, JCae2798 said:

Why can't we just have an option to disable this so that we don't have to worry about a trim system?

Because that interferes with how the helicopter actually works. No trim = no hold modes and incorrect SCAS logic. You can surely disable it within the cockpit on the UTIL page, but you might as well turn off the FMC channels as well.

In real life, the Force Trim system is only disabled if the system is malfunctioning or has had some sort of failure. There are reasons for this, because it is an integral part of the helicopter control system. As stated many times already, it isn't "just the trim system", the FTR switch itself interacts with the Flight Management Computer as well, which is why using it is necessary. If players fight against this, they will continue to experience difficulties.

[Hiob]

29 minutes ago, JCae2798 said:

As a clutch user, this system really bothers me.  I've read a lot on the trim system and this thread but continue to be unsure and frustrated how it works.  Why can't we just have an option to disable this so that we don't have to worry about a trim system?  Could this not be an option?

 

What do you mean with „as a clutch user“ if I may ask?

[JCae2798]

2 hours ago, Hiob said:

What do you mean with „as a clutch user“ if I may ask?

It's a system on joysticks that allow your stick to be left exactly where it is when you release your hands.  It's like pulling the springs out of it but adding tension (brakes) to hold the stick in place.

This is why I continue to be left confused on this topic.  I'm sure those that are familiar with the system and use it are also frustrated by users like me asking these questions but if the trim is to tell the aircraft where the new center point is, how is that different then what the clutch system is doing?  i guess that's why i keep getting stuck on having to trim when my stick is already in it's place and not being moved by force (spring for example)...

2 hours ago, Raptor9 said:

Because that interferes with how the helicopter actually works. No trim = no hold modes and incorrect SCAS logic. You can surely disable it within the cockpit on the UTIL page, but you might as well turn off the FMC channels as well.

I guess just to be clear, I can fly the thing pretty decently but I do find that it's extremely hard to keep it stable, I assume this is because of the SCAS/Trim system not being used by design...  Thanks for the tip, I'll see if this gives me a bit more control.

[Hiob]

22 minutes ago, JCae2798 said:

It's a system on joysticks that allow your stick to be left exactly where it is when you release your hands.  It's like pulling the springs out of it but adding tension (brakes) to hold the stick in place.

This is why I continue to be left confused on this topic.  I'm sure those that are familiar with the system and use it are also frustrated by users like me asking these questions but if the trim is to tell the aircraft where the new center point is, how is that different then what the clutch system is doing?  i guess that's why i keep getting stuck on having to trim when my stick is already in it's place and not being moved by force (spring for example)...

I guess just to be clear, I can fly the thing pretty decently but I do find that it's extremely hard to keep it stable, I assume this is because of the SCAS/Trim system not being used by design...  Thanks for the tip, I'll see if this gives me a bit more control.

Ah, ok. Thanks.

[Raptor9]

1 hour ago, JCae2798 said:

how is that different then what the clutch system is doing?  i guess that's why i keep getting stuck on having to trim when my stick is already in it's place and not being moved by force (spring for example)...

Because your hardware is simulating a different setup than what exists in the real helicopter. If it were the same, your stick would spring back to its last position where the Force Trim Release switch was last pressed.

And since the FMC, SCAS, and Hold mode logic all revolves around the concept that the cyclic (and pedals) is spring-loaded to the force trim reference, and it uses the force trim reference positions to drive its logic, any hardware that does not simulate this setup will lead to a false impression of how the force trim works, and how the FTR is interwoven into the overall FMC logic. So, if one were to press the Force Trim Release switch any time the controls are moved, the system would be used as intended and the logic would align, even if the force gradient that exists in the real helicopter isn't manifesting on your physical control stick.

Just because the force gradient isn't there, doesn't mean the remainder of the FMC logic can be ignored without creating issues. Remember, the logic of the FMC, SCAS, and Hold modes are based on the concept that the force gradient is there any time the FTR isn't pressed, and is not there any time the FTR is pressed, which is why the trim system should be used as if it were. The reason that Brad and I keep telling people to use the Force Trim Release switch isn't because people need to use it for the purposes of force trim, but for the purposes of employing the logic of the FMC, SCAS and Hold modes as they are designed. You may not physically need to apply a constant pressure to keep your physical stick in place without pressing the FTR, but the AH-64's Flight Management Computer sees this as if you do because that is how the real FMC is programmed, because in real-life the force gradient does exist. Therefore, the FTR needs to be used as it would in real-life; if the FTR switch is ignored, then the FMC will react as if the FTR were being ignored in the real aircraft as well.

If you had a pilot that was intent on muscling through the entire flight in a real AH-64 without pressing the Force Trim Release switch, they too would never be able to get a hold mode to engage properly, because they would be ignoring the underlying logic of how the FMC was designed and the purpose of its existence in the first place.

[JCae2798]

6 hours ago, Raptor9 said:

And since the FMC, SCAS, and Hold mode logic all revolves around the concept that the cyclic (and pedals) is spring-loaded to the force trim reference, and it uses the force trim reference positions to drive its logic, any hardware that does not simulate this setup will lead to a false impression of how the force trim works, and how the FTR is interwoven into the overall FMC logic. So, if one were to press the Force Trim Release switch any time the controls are moved, the system would be used as intended and the logic would align, even if the force gradient that exists in the real helicopter isn't manifesting on your physical control stick.

Holy <profanity> it just clicked!  Out of all the stuff I have read to date not one person has clearly mentioned that this is the way it works in real life!  Knowing this now makes me rethink the whole setup and i now see why and how it works.

So now knowing this I can see why some make actually prefer a spring setup over a clutch setup?  At least for this module...  I take this back, i can still see the benefit similar to a FFB stick...

Edited June 18, 2023 by JCae2798

[Raptor9]

I really wish more players would read the quick start manual starting on page 203, especially the sections talking about the force trim breakout values and the hold mode engagement logics. They would see how the cyclic and pedal force trim reference positions make the Force Trim Release switch the linchpin as to how these FMC functions work to control the aircraft.

[Floyd1212]

Or they could read the 32 page Force Trim thread...

On second thought, reading the Quick Start Guide is probably the way to go.

3 hours ago, Raptor9 said:

I really wish more players would read the quick start manual starting on page 203

Is this in the released manual, or an upcoming revision? Page 203?

[Raptor9]

8 hours ago, Floyd1212 said:

Is this in the released manual, or an upcoming revision? Page 203?

The current quick start guide, when it starts talking about the force trim breakout values, but also later in the section when it talks about the engagement logic for each hold mode. Pretty much each logic group graphic shows a force trim reference position within some axis being a factor of engagement. When violated, no hold mode.

Having said that, the upcoming manual revision is quite substantial, to include more in-depth explanations of the FMC functions and logic. But most of those graphics showing the engagement logic wont change.

[JCae2798]

10 hours ago, Floyd1212 said:

Or they could read the 32 page Force Trim thread...

I be fair I have and watched a number of videos but what finally clicked for me was that the real thing uses a magnet hold/spring feature that was unclear to me in the real thing.  Using the logic with my clutch system that where i leave me stick leaves the same result in game what's the point of the trim system?  I get everything else about how trim works and how it repositions the center, but when it comes to a clutch system and i never saw the value until it finally was clear that the real system has a system controlled magnet system on its center trim position that the system fights with.  Knowing this now makes it clear.

I will also add that flying without the trim system worked for me but would ever so slightly have the heli slowly steer off trim where now practicing a bit last night i see a bit more stabilization.  

When it comes to the manual I usually refer to Chuck's guides and again it wasn't clear to me reading any of it that it works this way.  It just explained what the trim system was doing which I already understood...which again was that it just recenters the center position of the stick but never went into depth about how the magnet system and FMC actually works.

 

EDIT:

And one last note about that other thread which I forget if it was Raptor or another ED member but there is so much back and forth and different points of what the system is doing maybe it just left me more confused than educated... 

Edited June 19, 2023 by JCae2798

[Raptor9]

1 hour ago, JCae2798 said:

And one last note about that other thread which I forget if it was Raptor or another ED member but there is so much back and forth and different points of what the system is doing maybe it just left me more confused than educated... 

I believe Floyd1212 was being sarcastic in stating to read that thread, for the very reason it was chock full of a lot of misinformation, ranging from slightly inaccurate to downright outlandish. I've unpinned that thread to prevent any confusion in the future, since Bradmick's video tutorial thread is a lot more useful, accurate, and is from someone that has thousands of hours flying and instructing the real AH-64D.

@bradmick and myself flew the real AH-64D for many years, so if we are refuting another's claims about the AH-64, it comes from a place of real-world knowledge and experience. There have been a number of self-proclaimed "experts" on these forums that have made some pretty interesting statements in the past about the AH-64 (and helicopters in general), and so if you see Brad or myself refuting them, that is the reason why and the source behind our responses.

[bradmick]

Yup, I still fly and teach folks how to fly the big rig. All my knowledge (like @Raptor9) is first hand, and not gleaned from a book with zero practical application of the books concepts and explanations.