Autopilot Steer Function .. Functional, But...

[Emmy]

...not quite accurate.

 

You'll see from these images that with the CDI pretty much centered up on 078, the jet is actually steering about seven or eight degrees right of the intended course:

 

HSI:

 

And the steerpoint is well to the left of center in the HUD:

 

Now, the system slowly tries to correct by starting a more and more aggressive left bank as you approach the steerpoint and while it may have actually gotten there by the time I crossed the steerpoint, it couldn't get there before I stepped to Steerpoint 3 at about five miles in order to "lead" the turn. You'll notice in the track that the jet also settled to the right of Steerpoint 3 as well before the track ends.

 

Thanks...

 

Track Attached...

AP Steering Error.trk

[backspace340]

Could that be the difference with magnetic declination? It's 7 degrees in Caucasus AFAIK

[Emmy]

Could that be the difference with magnetic declination? It's 7 degrees in Caucasus AFAIK

 

 

I suppose it's possible, but if it were, I think the jet would remain on a constant heading straight past the steerpoint with that same 7-8 degrees of offset but it doesn't. As I wrote, it slowly (at first) starts to correct with the bank angle increasing as you approach the active steerpoint.

 

Actually, I first noticed it on the Nevada map where it did exactly the same thing. Heading Command is also off by a few degrees relative to where you set the heading bug.

[Mike5560]

Is it not trying to fly the route though? As in put you back on the actual line that is drawn between waypoint?

[Emmy]

Is it not trying to fly the route though? As in put you back on the actual line that is drawn between waypoint?

 

 

That may also be possible, but in my example, it was roughly 20+ NM from Steerpoint 2 to Steerpoint 3 and I led the turn from 2 to 3 by about five miles which should have been plenty of room for the jet to settle right on the course line from 2 to 3 but it did not. It settled with the 7-8 degree error to the right of Steerpoint 3.

[Lace]

Wind drift? If you have a cross wind right-to-left you will not fly the planned track (078 deg), but several degrees to the right.

 

 

Granted seven or eight degrees is a lot of wind correction when traveling at 360kts. Must have been a bit breezy up there that day! (about 50kts full-cross off the top of my head).

[Emmy]

Wind drift? If you have a cross wind right-to-left you will not fly the planned track (078 deg), but several degrees to the right.

 

 

Granted seven or eight degrees is a lot of wind correction when traveling at 360kts. Must have been a bit breezy up there that day! (about 50kts full-cross off the top of my head).

 

Standard Day .. Zero Winds

[fagulha]

On the Hornet when i fly in the Persian Gulf the first thing i do is go to HSI and change the Magnetic heading to True Heading. In the Viper i don´t know if it is implemented or possible.

 

F.

[CobaltUK]

Have you mixed up heading select with steering select ? That was my 1st thought.

[Emmy]

Have you mixed up heading select with steering select ? That was my 1st thought.

 

Nope...

[Frederf]

I checked some shift occurs if you're in command steering (+a few degrees) or heading bug (-a few degrees), on Caucuses. Sort of odd how the shift is different directions in different roll modes.

I tried in NTTR and it's about -12 degrees in heading bug but little to none in command steering.

Summary is that heading and command steering are about 10-15 different from each other in both terrains but in Caucuses terrain it's about 50/50% too far left/right and in NTTR like 10%/90%.

Whatever problem it is full testing is to investigate both bug and INS steering on multiple terrains.

 

EDIT: Oh hey you can actually set the MAGV manually through the DED. Yeah, it has to be some kind of magnetic-true problem because if you change MAGV value the steering shift changes along with it.

Edited November 28, 2019 by Frederf

[randomTOTEN]

Try syncing your heading bug with the course. In your screenshot the aircraft is centered on the heading bug. This is a common design quirk of some RL general aviation systems.

[Emmy]

Try syncing your heading bug with the course. In your screenshot the aircraft is centered on the heading bug. This is a common design quirk of some RL general aviation systems.

 

I centered the heading bug on the actual direction the jet was flying while the CDI was centered on the desired course.

 

Have you done as you suggest and did it make a difference?

[Emmy]

I checked some shift occurs if you're in command steering (+a few degrees) or heading bug (-a few degrees), on Caucuses. Sort of odd how the shift is different directions in different roll modes.

I tried in NTTR and it's about -12 degrees in heading bug but little to none in command steering.

Summary is that heading and command steering are about 10-15 different from each other in both terrains but in Caucuses terrain it's about 50/50% too far left/right and in NTTR like 10%/90%.

Whatever problem it is full testing is to investigate both bug and INS steering on multiple terrains.

 

EDIT: Oh hey you can actually set the MAGV manually through the DED. Yeah, it has to be some kind of magnetic-true problem because if you change MAGV value the steering shift changes along with it.

 

Worth investigating. Nice find...

[Emmy]

Just a follow up...

 

MagVar is set automatically on the DED so I don't think it's a True Vs Mag issue. And it seems you can't manually change MagVar at this point in time so if it is True Vs Mag, then there's nothing you can do about it.

 

So maybe not a "Bug" in the truest sense, but it's a system that isn't functioning quite right (yet?)

 

 

Oh, and I let the jet continue bending to the left to reach the selected steerpoint and it just wanted to enter a left hand orbit at the selected steerpoint.

Edited November 29, 2019 by Emmy

[Emmy]

After playing with the modes some more, it's definitely following a True North course and not Magnetic. You need +6 degrees on the heading bug for Caucuses and +12-ish degrees for Nevada.