BALT Hold not maintaining bank?

[Nealius]

A while ago (>6 months), I used to set BALT AP while in a 30-degree bank to orbit and FENCE in, warm up Mav EO seekers, plug in laser codes, etc. Not just in the Hornet, but other modules like the Warthog and Harrier as well. The BALT AP would always maintain 30-degrees of bank until I disengaged the autopilot.

 

However, recently in the Hornet the BALT refuses to hold bank angle. I will set it at 30 degrees, take my hands completely off HOTAS and do my FENCE checks, only to find that I am now at 60 degrees of bank for some unknown reason. It does still keep my baro altitude, but the bank angle just goes nuts.

 

What's going on here?

[Skwinty]

Don't you need to use ATT hold as well to hold your attitude whilst BALT holds your altitude.

[Bunny Clark]

BALT is only an altitude holding program, if you want it to actively hold attitude you'll need to engage ATT as well. You can have both on at the same time. I believe there is a 45 degree bank angle limit to what the A/P will hold.

 

If you're trimmed out correctly, you shouldn't roll much even without ATT engaged. My guess is your recent experience was with an unbalanced load or not trimmed out just right, so the plane rolled on its own when you weren't looking.

[QuiGon]

You can have both on at the same time.

No you can't. I tried to do exactly that yesterday, when I wanted to enter an orbit over the AO, but there was no way to achieve this in autopilot, unlike it is with other aircraft.

BALT would level me out, flying straight ahead.

ATT would not keep altitude.

Both modes together can't be activated.

:(

[Skwinty]

If the attitude of the aircraft is nose high or nose low then BALT will disengage as there is conflict between BALT and ATT. Fly straight and level, engage BALT, bank to desired angle of bank and engage ATT. No reason for it not to work unless something has changed. It's been a while since I flew the Hornet.

[QuiGon]

If the attitude of the aircraft is nose high or nose low then BALT will disengage as there is conflict between BALT and ATT. Fly straight and level, engage BALT, bank to desired angle of bank and engage ATT. No reason for it not to work unless something has changed. It's been a while since I flew the Hornet.

Interesting, from other aircraft (A-10C) I'm used to first attain the desired level of bank and then engage the AP. I will try it the other way around next time.

Edited August 13, 2020 by QuiGon

[Captain Orso]

BALT will take you out of a very shallow dive or climb (well under 5° from my experience), but if your dive or climb is too steep, BALT will simply not engage.

[KLaFaille]

No you can't. ... Both modes together can't be activated.

:(

 

 

Have to be fairly level to begin with. Sometimes BALT won't engage if outside of parameters then even when you do go level again it still won't engage. Have to do some manual maneuvering to totally override any AP then level out and engage BALT again.

[Skwinty]

The Hornet does not have a regular auto pilot as found in other aircraft. The automation is for pilot relief as I understand. You still as you say initiate the attitude and then engage ATT.

[Nealius]

Isn't ATT only for pitch (i.e. "attitude")?

 

For clarification, I am level when I engage BALT, and the aircraft maintains level throughout the entire orbit. It's only the bank angle that gets fudged.

 

Bunny Clark might be on to something, because I often encounter it when running Double Ugly.

[Victor3]

No you can't. I tried to do exactly that yesterday, when I wanted to enter an orbit over the AO, but there was no way to achieve this in autopilot, unlike it is with other aircraft.

BALT would level me out, flying straight ahead.

ATT would not keep altitude.

Both modes together can't be activated.

:(

 

Not true, I've used both together multiple times in the last week.

[RedeyeStorm]

Me too. Maybe OP your joystick is giving inputs? That would prevent the autopilot from engaging.

[VFA41_Lion]

30 degrees of bank is a lot. I've found that your speed needs to be at a decent level for the system to hold or else the speed decay will disengage the autopilot.

[imacken]

I just don't understand this discussion. I mean, why would you want to have ATTH and BALT on at the same time?

BALT holds your altitude and roll angle, and ATTH holds your attitude, i.e. pitch as well as roll. Obviously, ATTH can't hold your altitude if it is holding a non-level pitch, so having both on is pointless as BALT holds alt and roll.

[Andartu]

I really dunno what some guys have for strange problems sometimes. You cannot have a different system/Sim/aircraft than I have..

 

I read these things so often in here or on reddit.

 

I don´t want to be rude really, I want to help! It is not my intention to be offensive ok.

 

But the first thing you have to ask yourself when something is not working from that you think its supposed to be to work is: "What I am doing wrong?" And not to blame the system in the first thought or thinking it is a bug (yes there are a lot of bugs I know).

 

And that means that you really need to read deep into the thing. At first NATOPS, then look if it is modeled in DCS, then do it precisely the way it is described via the official manual and/or chucks guide and/or everything that is available.

 

So after this, when all of this is excluded, and it still does not work, THEN you can think about a bug.

 

There is a reason why this thing is called "study level sim".

 

What I want to say is: Do it right, IF you have the intention to do it right.

I don´t get why people come to DCS and approach with an "arcadish" manner.

 

I don´t want to blame OP to be like that, just saying. Again, not by any means this is meant offensive.

 

 

So sorry, back to topic (not only answering OP, also the other posts to this point):

 

 

-Of course you can hold a bank angle in BALT only.

-Of course you can engage BALT and ATTH at the same time.

-The Hog´s AP is simply different to the Hornets AP.

-ATTH means attitude NOT altitude hold.

 

Offical actual DCS F/A-18C Manual:

 

ATTH: Attitude hold mode is selected. Attitude hold is engaged by pressing the option pushbutton next to the option display window displaying ATTH. Engagement is indicated by a colon in the ATTH option window. Currently the aircraft maintains the existing pitch and roll attitude.

 

BALT: Barometric altitude hold mode is selected. To establish barometric altitude hold, press the button next to the option display window displaying BALT. The existing barometric altitude at time of engagement is captured and maintained. Heading or attitude hold is maintained, depending upon which mode was previously engaged. The operating range is 0 to 70,000 feet. ATTH or HSEL can be selected with BALT to provide lateral control.

 

Also (even its not part of the thread):

 

HSEL: Heading select mode is selected. To establish heading select mode, select the desired heading on the HSI display by using the heading set switch, located to the left of the center DDI. Press the button next to the option display window displaying HSEL. The aircraft turns from existing heading through the smallest angle to the selected heading. Heading hold is reestablished after the selected heading is captured. Existing pitch attitude is maintained.

 

RALT: Radar altitude hold mode is selected. To establish radar altitude hold, press the pushbutton next to the option display window displaying RALT. Engagement is indicated by a colon appearing in the window next to RALT. The existing radar altitude is maintained upon engagement. Radar altitude hold coverage is from 0 to 5,000 feet. If no other mode is selected, the lateral axis control remains in heading hold. In this configuration, roll trim switch can be utilized with automatic turn coordination up to 45° with altitude maintained. ATTH or HSEL can be selected with RALT to provide lateral control.

 

Aside from that, there is a bug currently that appears sometimes (in my case at least) when you press BALT, the autopilot engages but the colon does not appear. Don´t know if that is reported already though.

 

So I rarely use ATTH actually cause BALT alone also holds my bank angle.

 

Sorry for the wall of text and all they typos that may be in it :book:

Edited August 13, 2020 by Andartu

[majapahit]

I do BALT circling all the time. Need to be shallow or you need to correct the drop until it holds. There's a gradient where BALT will hold or not, you can add stick (and throttle) whilst in BALT to correct drop, which has limits also YMMV. When BALT does not hold this means you need to switch to hand flying, that's all.

[docWilly]

BALT circling (solo) actually re-tested on lates OB without issues.

[Svend_Dellepude]

Me too. Maybe OP your joystick is giving inputs? That would prevent the autopilot from engaging.

 

^^^This

[Bunny Clark]

Alright, going back to NATOPS, this doesn't quite work the way I thought.

 

The baseline autopilot mode, "heading hold", which is activated by pressing ON/OFF on the A/P UFC page, or runs in the background when any of the other 5 modes are active, does the following:

 

• Holds the current pitch angle,
  
• If angle of bank is less than 5 degrees, current magnetic heading is held,
  
• If angle of bank is more than 5 degrees, bank angle is held.
  

 

I didn't realize that either the first or last points was a part of heading hold, I had thought both of those were only available in Attitude Hold. So apparently the only reason to ever use Attitude Hold is if you want to hold a bank angle of less than 5 degrees? That seems weird, but it's what's described in NATOPS and how it works in-game.

 

Control Stick Steering (CSS) works the same way in heading hold and Attitude Hold as well, so there's not even a difference there.

 

But I just re-checked on current Stable and everything is working in-game as described in NATOPS. I can enable both ATTH and BALT at the same time, regardless of which order I enable them. And my out of balance hypothesis seems to be wrong as well; I tested with 4 bombs on one wing and none on the other with neutral trim and while both heading hold and ATTH struggled with precision, both roughly held angle of bank successfully.

 

Perhaps your stick isn't centering perfectly? Small stick inputs while A/P is active won't disable A/P as suggested above, but it will command CSS which could slowly change the commanded angle of bank.

Edited August 13, 2020 by Bunny Clark

[majapahit]

Alright, going back to NATOPS, this doesn't quite work the way I thought.

 

The baseline autopilot mode, "heading hold", which is activated by pressing ON/OFF on the A/P UFC page, or runs in the background when any of the other 5 modes are active, does the following:

 

• Holds the current pitch angle,
  
• If angle of bank is less than 5 degrees, current magnetic heading is held,
  
• If angle of bank is more than 5 degrees, bank angle is held.
  

 

I didn't realize that either the first or last points was a part of heading hold, I had thought both of those were only available in Attitude Hold. So apparently the only reason to ever use Attitude Hold is if you want to hold a bank angle of less than 5 degrees? That seems weird, but it's what's described in NATOPS and how it works in-game.

 

Control Stick Steering (CSS) works the same way in heading hold and Attitude Hold as well, so there's not even a difference there.

 

But I just re-checked on current Stable and everything is working in-game as described in NATOPS. I can enable both ATTH and BALT at the same time, regardless of which order I enable them. And my out of balance hypothesis seems to be wrong as well; I tested with 4 bombs on one wing and none on the other with neutral trim and while both heading hold and ATTH struggled with precision, both roughly held angle of bank successfully.

 

Perhaps your stick isn't centering perfectly? Small stick inputs while A/P is active won't disable A/P as suggested above, but it will command CSS which could slowly change the commanded angle of bank.

"heading hold"?

there is

Attitude Hold (ATTH): attitude <45° bank <70°, or

Heading Select (HSEL): which you dial in on the HSI

Control Stick Steering (CSS)

[Bunny Clark]

"heading hold"?

Yes. As I said before, it's a baseline mode that can be independently activated with the ON/OFF button, or comes on with any of the other 5 modes. If you activate any of the other 5 modes and then deactivate them with the relevant option select button, heading hold will remain on. When heading hold is active by itself, "A/P" is displayed on the left DDI advisory line. The only way to deactivate heading hold is with the paddle switch.

 

See NATOPS I-2-60

[majapahit]

Yes. As I said before, it's a baseline mode that can be independently activated with the ON/OFF button, or comes on with any of the other 5 modes. If you activate any of the other 5 modes and then deactivate them with the relevant option select button, heading hold will remain on. When heading hold is active by itself, "A/P" is displayed on the left DDI advisory line. The only way to deactivate heading hold is with the paddle switch.

 

See NATOPS I-2-60

errr, that's the Control Stick Steering (CSS), why invent names that suppose a relationship with 'heading' which is not the case.

Where in NATOPS would it say 'there is a baseline autopilot mode which is referred to as "heading hold'' by NATOPS.

[imacken]

No, he is right, there is another mode, and shows as A/P on the DDI. It is operational when one of the other modes is switched off, or you push the on/off button. Personally, I have not been able to ever see the difference between A/P and ATTH.

I've never seen the basic A/P being called 'heading hold', though, I must admit.

[imacken]

Where in NATOPS would it say 'there is a baseline autopilot mode which is referred to as "heading hold'' by NATOPS.

 

Er, well actually, it says exactly that on page I-2-61!

[Bunny Clark]

errr, that's the Control Stick Steering (CSS), why invent names that suppose a relationship with 'heading' which is not the case.

Nope, CSS is a function, and it works in multiple modes. CSS works for pitch and roll in both heading hold and ATTH, and it works for roll only in RALT.

 

Where in NATOPS would it say 'there is a baseline autopilot mode which is referred to as "heading hold'' by NATOPS.

Section 2.9.2.1 Autopilot.

 

Personally, I have not been able to ever see the difference between A/P and ATTH.

As far as I can tell, the only difference is that ATTH will hold a bank angle of less then 5 degrees, where heading hold will correct that angle to 0.