INS alignment

[caponi]

what is the indicator that the INS alignment was successful ?

except i had a stop watch and count 4 minutes :D

[Stubbies2003]

Flashing RDY on the INS page prior to selecting NAV.

[caponi]

:thumbup:

[QuiGon]

Alignment is probably not implemented yet, so you can just skip it and put it so NAV instantly, similar to the Hornet.

[caponi]

are u right with the Hornet ?

if i skip the INS alignment, the way point distance will not refresh in flight ...

and i will not have a map ...

 

may be that the alignment is in WIP, but it has consequences if u skip it ... :music_whistling:

 

i would prefer that the F16 INS works without skipping ...

[QuiGon]

are u right with the Hornet ?

if i skip the INS alignment, the way point distance will not refresh in flight ...

and i will not have a map ...

 

may be that the alihnment is in WIP, but it has consequences if u skip it ... :music_whistling:

Yes, untill the last update you could just skip it. With the most recent update ED introduced some alignment functionality that is very much WIP and finishes way too fast. You can still just skip it, but then you have to push some buttons on the HSI to tell the system what your current position ist (press WPDSG, UPDT, DSG, ACPT on the HSI and then press the NWS button). Sometimes you even have to do that, because the alignment doesn't work at all sometimes (especially when flying on red side).

 

 

i would prefer that the F16 INS works without skipping ...

Yeah, me too! I hope tomorrows update will introduce a working INS alignment for the Hornet at least!

[caponi]

yes +2 :thumbup:

[sirrah]

In relation to the OP question.

 

I always thought that the F-16 alignment took more or less 8 minutes and that, when stopped earlier, it would greatly reduce accuracy (kinda similar to the Cat). Or is this only the case for the F-16A/B MLu versions?

 

Maybe someone with some F-16 avionics background can clarify this?

[mvsgas]

In relation to the OP question.

 

I always thought that the F-16 alignment took more or less 8 minutes and that, when stopped earlier, it would greatly reduce accuracy (kinda similar to the Cat). Or is this only the case for the F-16A/B MLu versions?

 

Maybe someone with some F-16 avionics background can clarify this?

 

I do not have an avionics background, but the alignment time would depend on the Inertial Navigation Unit (INU) used on the aircraft, the type of alignment being performed, whether you are inside of a Harden Aircraft Shelter (HAS) or not, etc.

 

And yes, if not fully align there will be degradation of accuracy over time.

[Flamin_Squirrel]

...whether you are inside of a Harden Aircraft Shelter (HAS) or not...

 

Why would a HAS make any difference? Accuracy will degrade with time, fully aligned or not.

 

I believe latitude makes a difference to alignment time also.

Edited October 2, 2019 by Flamin_Squirrel

[Tomsk]

No expertise, but I seem to recall hearing the EGI version aligns quicker. Which it seems is the version we've gotten.

[mvsgas]

Why would a HAS make any difference?

If GPS can get a signal, Alignment method will change

 

Accuracy will degrade with time, fully aligned or not.

true

 

I believe latitude makes a difference to alignment time also.

Not as indicated in aircraft manuals

 

Edit Just notice, meant if GPS can't get a signal inside the HAS.

Edited October 2, 2019 by mvsgas

[Krippz]

I don't think they modeled the alignment yet. But you can see the status of the alignment by pressing List and then 6 on the UFC to bring up the INS page on the DED.

[Flamin_Squirrel]

If GPS can get a signal, Alignment method will change

 

Hmmm, you sure? You can tell the aircraft where it is by entering your current co-ordinates, so how would GPS help? The plane already knows where it is.

 

Not saying you're wrong, it just doesn't seem intuitive (to me at least).

 

Not as indicated in aircraft manuals

 

I couldn't see much on the subject in the -1, but I didn't look that hard I have to admit. We're not flying around the arctic so I guess it doesn't matter too much!

[Harlikwin]

The major consideration is how much of the constellation is up and visible to the GPS receiver. More sats=less time and better accuracy.

[EvanWeeks]

The plane already knows where it is.

 

It knows this because it knows where it isn't?

 

/meme :D

[Flamin_Squirrel]

OK, but how does GPS help alignment if the plane already knows where it is?

[Harlikwin]

It knows this because it knows where it isn't?

 

/meme :D

 

LOFL... I love that video.

[Rainmaker]

There’s a lot of mixing terms here.

 

There are a few here that can get in the weeds with this (as I know a few on here have pointy head experience), but INS and GPS have to be thought as to separate things because in reality they are. INS uses gyros to spin and align, GPS uses satellite triangulation. On an EGI system, they both can be used in concert with one another. INS has to “spin up” to align, GPS works just like your commercial GPS.

 

Yes, present position can be manually entered to speed up the process, or can be stored from previous alignment. The issue becomes when you tow the jet, or it’s moved from it’s last known position. From there, it has to realign itself.

 

GPS picks up satellites, calculates heading, alt, PP...and it’s basically good from there. It also doesn’t have the drift issues that INS has, which is why it’s favored from an accuracy standpoint.

 

EGI systems can use both, or one or the other, based on pilot preference depending on the aircraft. Some use INS as primary and some use GPS. If blended, the aircraft is going to compare both signals to try and give you the best accuracy.

[mvsgas]

I but the alignment time would depend

 

Hmmm, you sure? You can tell the aircraft where it is by entering your current co-ordinates, so how would GPS help? The plane already knows where it is.

I was talking specifically about time to align. again, depending on the system, the INU, the method to align and whether GPS has a signal or not. If no GPS signal, depending on the system, additional steps are needed prior to alignment, thus changing time to align.

 

I couldn't see much on the subject in the -1, but I didn't look that hard I have to admit. We're not flying around the arctic so I guess it doesn't matter too much!

The information would be in the 1F-16CM-34-1-1 circa 1 June 2007

Para 2.2.3 page 2-162 to 2-177 for RLG and para 2.2.4 page 2-178 to 2-188 for EGI

But that is just a guess, since I do not have one.

[Harlikwin]

There’s a lot of mixing terms here.

 

There are a few here that can get in the weeds with this (as I know a few on here have pointy head experience), but INS and GPS have to be thought as to separate things because in reality they are. INS uses gyros to spin and align, GPS uses satellite triangulation. On an EGI system, they both can be used in concert with one another. INS has to “spin up” to align, GPS works just like your commercial GPS.

 

Yes, present position can be manually entered to speed up the process, or can be stored from previous alignment. The issue becomes when you tow the jet, or it’s moved from it’s last known position. From there, it has to realign itself.

 

GPS picks up satellites, calculates heading, alt, PP...and it’s basically good from there. It also doesn’t have the drift issues that INS has, which is why it’s favored from an accuracy standpoint.

 

EGI systems can use both, or one or the other, based on pilot preference depending on the aircraft. Some use INS as primary and some use GPS. If blended, the aircraft is going to compare both signals to try and give you the best accuracy.

 

:thumbup:

[sirrah]

There’s a lot of mixing terms here.

 

There are a few here that can get in the weeds with this (as I know a few on here have pointy head experience), but INS and GPS have to be thought as to separate things because in reality they are. INS uses gyros to spin and align, GPS uses satellite triangulation. On an EGI system, they both can be used in concert with one another. INS has to “spin up” to align, GPS works just like your commercial GPS.

 

Yes, present position can be manually entered to speed up the process, or can be stored from previous alignment. The issue becomes when you tow the jet, or it’s moved from it’s last known position. From there, it has to realign itself.

 

GPS picks up satellites, calculates heading, alt, PP...and it’s basically good from there. It also doesn’t have the drift issues that INS has, which is why it’s favored from an accuracy standpoint.

 

EGI systems can use both, or one or the other, based on pilot preference depending on the aircraft. Some use INS as primary and some use GPS. If blended, the aircraft is going to compare both signals to try and give you the best accuracy.

 

Thanks for this explanation :thumbup:

 

Still I wonder, am I correct that F-16A/B MLu alignment takes approx. 8 munutes, while the F-16C/D block50 aligns in 4 minutes (as the OP checked on his stopwatch)? Or is the correct alignment time not implemented yet maybe?

[Flamin_Squirrel]

So it might be worth describing how an INS aligns. At least, this is my understanding. I'm happy to be corrected, 'cos I find this stuff interesting and want to get it right.

 

INS requires that it knows its current lat/long prior to alignment. That generally comes from pilot input, or GPS in most modern aircraft. Once the INS has this info, alignment begins; it does this by using 3 gyros (one in each axis) to sense how each one precesses, caused by the earth's rotation. Combined with knowledge of where it is on the planet from the earlier entered lat/long, it can establish where it is pointing in 3D space, including which direction true north is.

 

So, assuming my understanding is correct, the alignment time is in large part due to the need for the earth to rotate enough that the INS can detect said rotation, in order to establish orientation (rather than position). As far as I'm aware GPS can only help with position, so how does it help speed up alignment?

[Rainmaker]

Thanks for this explanation :thumbup:

 

Still I wonder, am I correct that F-16A/B MLu alignment takes approx. 8 munutes, while the F-16C/D block50 aligns in 4 minutes (as the OP checked on his stopwatch)? Or is the correct alignment time not implemented yet maybe?

 

I asked roughly the same question in the EGI thread with regards to the 8 vs 4 and when/why it changed. I never got an answer. Someone out there probably knows, but it isn’t me.

[Flamin_Squirrel]

It cannot speed up, but it can slow down if ttff is too long.

 

Btw, INS finds its own latitude. Pilot or gnss enters the latitude for sake of error detection. If entered and calculated latitude don't match, it displays some error code.

 

Btw2, INS can speed up gnss ttff.

 

:thumbup: