INS alignment Initial POS doesn't matter.

Isn't the IFA the in flight alignment?

Isn't the IFA the in flight alignment?

It is but the RL manual floating the net and the pocket guide we get from RAZBAM describe it as the normal operation position after initial alignment.

The notion that IFA and NAV are different because IFA includes continuous GPS updates while NAV does not is missing out on a bigger picture.

IFA is both a method to align the system completely (from OFF >30s) while airborne as well as a method to maintain position-keeping after a normal full ground alignment.

The coupling mode/position keeping modes are:

DGD/INS

DGD/GPS

DGD/ADC

DGD/

POS/INS

POS/GPS

IFA POS/INS

IFA POS/GPS

When the switch is in "NAV" or similar unselected deficiency the coupling mode is loose and DGD/ is shown. When the switch is in "IFA" and functioning normally the coupling mode is tight and POS/ is shown.

The last two modes which have "IFA" in them are only displayed when the INS is not aligned but "IFA" is selected by the switch. This would be the case when taking off before a complete alignment or performing an alignment while airborne. The IFA label disappears when the INS has accepted the alignment and is functioning normally. If a complete alignment is done on the ground the "IFA" label is never seen.

It may be tempting to think that POS/GPS is the superior mode. That is not the case. POS/INS is the best quality mode. When tightly-coupled POS is displayed and the GPS, ADC, and INS are all aiding each other. You want the INS as the position-keeping source. The GPS's benefits are realized because the INS is tightly-coupled to the other systems. You do not normally want to have GPS be the PK source when flying.

The second half of the mode is the position keeping source, ADC INS GPS in that priority order. In ADC the airplane maintains position information based on low-quality ADC inputs like TAS and AOA. ADC cannot be used as a PK source in tightly coupled mode. In tightly-coupled other sensors are continually used to refine the alignment while in flight.

Notice that DGD/GPS mode exists which uses GPS as a PK source but is not tightly-coupled meaning that you can have a GPS PK source but despite showing GPS position the INS is not being aided by GPS. For example setting the switch to "NAV" but cycling the EHSD button so that the PK source to GPS would do this.

The system's sensitivity and requirement for:

Position

Magnetic heading

Magnetic variation

entered info vary from situation to situation. E.g. a GPS carrier alignment performs a wide angle alignment first and doesn't need an entered heading. A manual sea alignment does.

As the title says, no matter what LL you enter it seems to make no difference. I spawned at Maykop and entered Vaziani's LL as if it were my initial POS. It aligned perfectly right over my parking spot at Maykop. Shouldn't it be offset or something? Is this a bug or an incomplete feature?

Wait...You Spawned at MAYKOP...Entered Vazianis L/L and youre questioning why it worked properly?

Wow nice comprehension skills. Read the thread again please.

If the INS is ONLY coupled with GPS in IFA Mode, how come that the moving map knows your correct position, despite you aligned with wrong coordinates and the mode selector knob went to" NAV" after "INS GND"?

(You don't even have to touch the mode selector after alignment)

I think it's a minor bug. As I am no expert I would suspect the moving map-feature relies on the Navigation system and is not linked seperately e.g. with the pilots mobile phone...

If the INS is ONLY coupled with GPS in IFA Mode, how come that the moving map knows your correct position, despite you aligned with wrong coordinates and the mode selector knob went to" NAV" after "INS GND"?

It shouldn't, it should show an alignment error in a similar way as the M-2000C.

I think it's a minor bug. As I am no expert I would suspect the moving map-feature relies on the Navigation system and is not linked seperately e.g. with the pilots mobile phone...

IMHO, not so much a bug as WIP or a unmodelled feature.

Thank you for your answer Ramsay, but I don't get it. Why should it show an alignment error?

Should it not act like correctly aligned, with that data you fed it, including wrong coordinates and wrong position on map?

Thank you for your answer Ramsay, but I don't get it. Why should it show an alignment error?

AFAIK with an incorrect alignment position, a flight plan and it's waypoints will be offset to the moving map until a GPS or pilot position fix corrects the error.

This example from Heatblur's DCS F-14 shows the effect INS error build up over time - on return to Nellis AFB (blue line), the INS thinks the F-14 is landing in the desert to the North, rather than on the runway.

AFAIK deliberately entering the wrong initial position or heading has a similar effect.

Should it not act like correctly aligned, with that data you fed it, including wrong coordinates and wrong position on map?

Waypoints are entered using Lat/Long, so their position will be correct on the moving map, however the EHSI/HUD director would guide away from their 'real' location as the aircrafts own position is incorrect on the map i.e. the INS in the above example would guide the F-14 to ' RWY 21', 10km south of it's real location, unless a position fix was taken to correct the error.

IIRC INS drift for the AV-8B is approx 1nm per hour and drift rates greater than 1.5nm require investigation.

Heatblur's original thread: DCS F-14 Update - All About Inertia!

All non-stored heading alignments have a wade angle gyrocompass stage which finds the heading to ~2° and do not require heading pilot entry. Stored heading alignments in which the stored heading is wrong (either moved or the ship heading is wrong or both) may cause align failures. Sea stored heading doesn't save the actual heading but the relative angle from the ship's heading. Basically all stored-heading alignments skip the wide angle step and save 1-4 minutes for ASN-130 systems (ASN-139 presumably faster). Heading errors of ~10° may cause an alignment failure.

Refinement of the small angle alignment heading should be largely independent of the supplied heading or discovered rough heading. Perhaps the alignment quality isn't as good or takes longer with poorer initial data.

All alignments are sensitive to initial position entered except IFA (carrier or airborne) since they are GPS-sourced. SINS provides the reference position over the link. With ground alignment the reference position is waypoint zero. The only time the pilot would be required to enter a manual initial position is sea manual alignment.

The GPS may be used as a manual position update source even in NAV mode.

The AV-8B has 3 levels of drift compensation (factory, permanent, and sortie). If a good flight was made with less than 1nm/h drift the permanent bias can be modified at shutdown. The sortie bias is made during alignment and lost at shutdown. Using the IFA mode the permanent bias can be adjusted based on IFA use that flight.

AFAIK with an incorrect alignment position, a flight plan and it's waypoints will be offset to the moving map until a GPS or pilot position fix corrects the error.

 

[...]

 

Waypoints are entered using Lat/Long, so their position will be correct on the moving map, however the EHSI/HUD director would guide away from their 'real' location as the aircrafts own position is incorrect on the map i.e. the INS in the above example would guide the F-14 to ' RWY 21', 10km south of it's real location, unless a position fix was taken to correct the error.

 

IIRC INS drift for the AV-8B is approx 1nm per hour and drift rates greater than 1.5nm require investigation.

 

Heatblur's original thread: DCS F-14 Update - All About Inertia!

That's what this thread is all about. Despite an incorrect alignment position, the position of the own aircraft on the moving map is correct.

1. Post

As the title says, no matter what LL you enter it seems to make no difference. I spawned at Maykop and entered Vaziani's LL as if it were my initial POS. It aligned perfectly right over my parking spot at Maykop. Shouldn't it be offset or something? Is this a bug or an incomplete feature?

5. Post

Just tried it myself. It alligns perfectly with completely wrong coordinates, without switching to IFA or something else. This seems to make the whole alignment process useless. :huh:

 

EDIT: O.K. tried it again. It's only the moving map. Wrong coordinates stay wrong.

Conclusion:

[...]

 

Maybe a dev can chime in and explain how it should work.

1 Week has gone by and the whole issue inflated to 4 pages.

Another issue seems to be the ability to bypass an alignment by going straight to gyro and back to IFA.

Waypoints and markpoints won't work for about 3 min until the IFA is done, but you will get all hud symbology including velocity vector and other systems that would rely on the INS.

Also as far as I know IFA should take up to 10 min while flying or moving but it seems to take only 3 no matter the situation.

At this point inputting correct INS initial POS or even waiting to move before it is done is an act of masochism.

I really wish the devs would acknowledge these issues, because I'm afraid if they don't we will never see them fixed.

This is EA and what is the point of EA if members of the community report bugs or issues and no one from the development team listens or chimes in if said issues are not bugs? How are we to know if our issues are being looked into?

The out of EA by the end of the year timeline I have heard mentioned seems like a long shot unless the plan is to stick us with a broken unfinished product. I hope this timeline is extended for the sake of all owners of this module.

With that being said I do love this module and hope RAZBAM makes it as awesome as I know it can be.

Irl doesn't the ground crew set initial pos and other parameters?

For GND, GPS/IFA, and SEA alignment initial position comes from waypoint 0, GPS, and SINS data respectively. The pilot will not normally enter values for alignment. It wouldn't be ground crew but data cartridge if any data is to be pre-entered. If any ground crew action was to be done it would be to align and shutdown before the pilot arrives so he could make use of the stored heading alignment.

That makes sense.

Ya but if the aircraft has been moved since the last alignment then the stored heading would be incorrect.

Funny thing is that I have shut down and repaired my airplane and stored heading alignment is not an option upon restarting the aircraft.

It seems to only work when that option is selected.

Although there are serious issues, please don't forget this one

* bump :D

Bumping for RAZBAM attention.

We'll check. Thanks.