GBU 31\38 and ramp start.

[LeadDoctor]

After half a year break and installing DCS world I've ran into a brick wall. For some reason I can't get GBUs to release\go green when I ramp start. They work fine when starting a mission in the air or if I do the start up training. Tried to many check list, watched too many videos. My brains are blowing out please help! lol Only clue I got is on the hud it shows aln uns.

Edited October 20, 2012 by LeadDoctor
UNS not cdu

[BlueRidgeDx]

It means ALIGN UNSATISFACTORY. That is, the transfer alignment is insufficient for weapon guidance.

 

Make sure that you're performing a full gyrocompass "ground" alignment. You need to let the EGI go for the full 4 minutes and the INS NAV RDY indication begins to flash. Only then should you press the NAV button and engage EGI mode from the NMSP.

 

It is possible for the weapons' transfer alignment to degrade if you sit motionless on the ground, or fly straight and level for prolonged periods (10-15 minutes). This is normal, and you should simply turn the aircraft about 90 degrees if on the ground, or maneuver the aircraft left/right if in the air. This should restore an ALN RDY state.

[YoYo]

Wait to TIME: 4.0.0.8 on MFD->CDU. Will be ok after this.

Gps must setu up.

[LeadDoctor]

Thanks, turns out I wasn't waiting long enough. Funny how few minutes worth of patience can save hours of frustration.

[Boston87]

I'm lost? How can I let the EGI run for 4 min if I can't turn it on? And what NAV button?

[IonicRipper]

When you start from the ramp with a cold plane, once you turn on the EGI it will go through an alignment process which takes a few minutes. You can see how much time its been on the CDU (T= 0.0.0.0.) If i recall correctly it takes 4 minutes. Once the INS NAV RDY is flashing you can then press the NAV mode on the CDU (3rd from the top on the right.)

 

The manual describes all of this starting from page 414.

Edited April 1, 2013 by IonicRipper

[Boston87]

OK BUT.....when i open the CDU the INS NAV RDY was blinking but i it was still ULN UNS

[Zenra]

I'm lost? How can I let the EGI run for 4 min if I can't turn it on? And what NAV button?

 

You can turn it on, using the switches on the Auxiliary Avionics Panel, as soon as you have the APU Generator on line. Probably ground power would work as well, but I have not tried this personally since DCS World. Alignment will proceed while you go through the rest of your preflight checks.

[Zeke]

The GBU-38's are a little strange in their behavior. They will align just give them time. They go from ALN UNS to ALN RDY after a little while after nav align is ready and you hit the EGI button. Once you start taxing and you turn left or right they'll go to RDY.

 

Also, I've noticed they will go back to ALN RDY when changing SPI, entering a new WP in the CDU and turning on the GUNPAC. You can get them to go back to RDY mode by simply banking left or right in flight.

 

Don't know if this is a bug or what, but you need to keep an eye on them before launching them. I've found out the hard way and learned of this fix by searching these forums.

[Evil.Bonsai]

0.0.0.0 to 4.0.0.8 isn't time, it's a test bit sequence that you can't interrupt without having to start all over again.

 

No, that's incorrect. Half of that is time 0.0-4.0 is 0-4 mins, which is how long it takes to complete the alignmient. The 2nd set of number #.#-0.8 is the 'error' of posiition, in nm I believe. Number starts high, and as it align it gets smaller and smaller until it reaches 0.8.

 

As to the previous question regarding NAV INS ready, that starts blinking when Navigational INS is ready. However, other instruments require better positioning than what is used for INS. Your TGP needs the data so that when your pointing at something with it, you can set a SPI and attack targets. If you don't allow full alignment, precision weapons like JDAMS will never hit their target and your SPI won't be accurate.

[hannibal]

Is it ok to rearm / load GBU 31/38 before performing cold start procedures or rearm / load after INS alignement?

im trying to narrow down a procedure for a manual cold start to use JDAMs

[Yurgon]

38 minutes ago, hannibal said:

Is it ok to rearm / load GBU 31/38 before performing cold start procedures or rearm / load after INS alignement?

Both ways are perfectly okay.

If you load weapons after the jet is powered up and you've gone through the startup procedure (this also applies when you rearm mid-mission), don't forget to tell the jet what weapons are loaded through DSMS -> INV or simply by reloading the entire DSMS through LOAD -> DSMS.

Either way (loading weapons before INS alignment or after) does not affect Inertially Aided Munitions (well... obviously if you never get INS aligned, they won't work, but I guess that goes without saying ).

Turning by 90° or more, or rocking the wings, will always transfer the jet's inertial alignment onto the weapons, so if your IAMs ever go ALN RDY or ALN UNS, just rock the wings or turn by 90+ degrees, and they should switch back to RDY.

As said above, prolonged level flight can make IAMs drop from RDY to ALN RDY or ALN UNS and make them unusable until the next transfer alignment.

Note, there have been user reports that this will now happen much faster than it did in the past, with just a few minutes of level flight being enough for IAM status to drop. Then again, once you know about it, just plan for a turn or several shortly before engaging anything with IAMs, and if the status still drops, just rock your wings and they should get back to RDY right away.

43 minutes ago, hannibal said:

im trying to narrow down a procedure for a manual cold start to use JDAMs

Personally, I prefer to load weapons while the jet is still cold, for the simple reason of avoiding LOAD -> DSMS after I've already gone through LOAD -> ALL during the startup process. But depending on the level of realism you're aiming at, you might find yourself parked at a ramp or shelter that doesn't allow loading of certain types of ordnance per local procedures, so you might need to taxi to an arming area (like LOLA/CALA at Nellis), load live weapons and reload DSMS. But again, to the best of my knowledge this does not affect precision or anything else about IAMs.

[hannibal]

ok, appreciate reply. going to adjust my personal start up procedure. i guess my culprit is the fast align, i was following tricker's 60 sec hog start.. so, i have to remove that out of the startup equation