DC-8 Autopilot INS

[Pedro]

Hello to all,

First of all, allow me to thank to the HJG team for making such a wonderful work in creating these amazing classic aircraft´s, that bring an imense joy to everyone who likes classic stuff in there FS.
I´ve created this thread because I came across a problem with the DC-8-73F with INS panel.
Before I created this thread, I´ve also looked in the Douglas Support Forum but I couldn´t find nothing on this.
So, my problem is: I´ve set up a flight from Nellis AFB to Edwards AFB, I program the INS acordingly with the waypoints, Taxi to the RWY, and Take Off, after taking off and turn on the Autopilot and swich to INS mode, the Autopilot does not follow the INS Instructions. This is Happening only with the DC-873F, and Convair CV-990A (INS)
I have follow the instructions precisely for installing the Aircraft in FS9, I´ve also the B707 and B727 but I dont have this issue with these Planes.
Thank you very much in advance, for the work and support.
I want to appologize for my bad english because is not my main language.

[aerofoto - HJG Admin]

Pedro .... have you ensured the INS has been properly aligned "prior to" commencing of your virtual flight .... or that the INS NAV has been correctly engaged "through the AP" upon commencing your virtual flight ?

I've referred your query to Nathan whom is "a little more" familiar with the HJG supplied INS than I am.

I'm confident he'll get back to your .... as soon as is convenient for him to do so at this time of year.

In the mean time please refer to both of our following INS tutorials in order to try'n identify where you may be going wrong ....


INS TURORIAL
tonymadgehjg.proboards.com/thread/9801/ins-tutorial

INS TURORIAL VIDEO
tonymadgehjg.proboards.com/thread/8957/ins-tutorial


Although each of the above tutorials may related to different HJG simulations the INS we provide functions identically for each .... so far s I'm aware .... so .... there shod b no difference/s in regard to either it's programming or functionality among any of the simulations we provide that are INS featured.

Again .... I've referred your query to Nathan, so, please await his advice please.

Mark C
AKL/NZ

[Nathan Ford - HJG]

Hi Pedro, welcome to the forums.

Can I check that after takeoff, but before you turn the autopilot to INS that you have done the following?

-Ensure that the DATA SELECTOR switch is on DIS/TIME.
-Press the WPT CHG button.
-Enter 0 1 into the FROM TO display.
-Press INSERT. This will create a Leg from the airplanes current position to waypoint 1 stored in the INS.

This is used to create a leg from your current location to the first waypoint you have entered into the INS. Without this, the INS won’t know how to get to your first fix and the autopilot will have nothing to follow.

Cheers,
Nathan 🤓

[Pedro]

Hello Mark and Nathan, thank you very much to both for your really quick reply.

I ensured that the INS was properly aligned (waited aprox. 20-30 min, or fast align cheat), I´ve waited until the "Performance Index" was equal to 0 and after taking off ensure that the knob on the A/P was set to INS.
I also saw the tutorials, wich by the way, are very well done and easy to understand with much good information, thank you very much for these recomendation.
I ensured that the DATA SELECTOR was set to DIS/TIME and insert the 0 to 1 in the FROM TO display, I made this last step while still on the ground.
It´s important to mention that, I start the flight from a Cold and Dark situation and from a save flight, maybe this is creating the problem ?
I will try again a new flight and see if it works.

Thank you very much once again for your time and quick reply.

Wishing you all the best for these new year,

Kind Regards,

Pedro

[aerofoto - HJG Admin]

I've asked Nathan to have a closer look at this .... as soon as is convenient for him, so, give him a few days grace please

As you seem to be familiar with the INS .... per other HJG panels which are INS featured, but, which aren't presenting any issues for you then it's odd that what you're experiencing should affect just the CV-990A INS and DC-8-72/73 INS panels only.

For this reason I've asked Nathan to run some "fidelity checks" .... and which will take a bit of time if you don't mind awaiting his report/analysis and advice

Mark C
AKL/NZ

[Nathan Ford - HJG]

Thanks Pedro, I’m flying today, but should hopefully be able to get on the sim tonight, if not, I can have a look tomorrow 🤓👍🏻

Cheers,
Nathan

[Pedro]

Thank you once again for your time and avaliabillity to help me with this issue.
Apart from the DC-8-73F and Convair CV990A, I currently have the L-1011, B707-320B, B727-200, DC-10-30F, in all of these planes the INS works perfectly.
The only addons that I have on my FS9 are only HJG planes, all the scenery is default.
If Nathan want to recreate my flight (KLSV to KEDW), here are the coordinates:

1-N34º 47´49.30´´;W116º 27´46.51´´

2-N34º 42´16.29´´;W117º 22´57.18´´

3-N34º 36´58.63´´;W117º 57´ 37.47´´

4-N34º 37´45.18´´;W118º 08´ 15.89´´

5-N34º 39´41.05´´;W118º 12´ 01.77´´

6-N34º 48´17.77´´;W118º 04´ 33.13´´

Prior to the flight, since the default Nellis AFB scenery don´t have AFCAD´s, I move the Aircraft with slew, to a position near the Runway, and start the flight from there.
Thank you once again for your help, availiabillity and time.

Kind regards,

Pedro

[Pedro]

Please Nathan, whenever you have the time, I don´t want to disturb you !

Thank you very much for your time and attention.

Kind regards,

Pedro

[aerofoto - HJG Admin]

I move the Aircraft with slew

It's possible, although I can't and therefore don't say this for certain, but, suddenly re-positioning the simulation using FS SLEW MODE and "after" first having programmed the INS may upset it.

If you've been doing this with each of our other INS featured panels/simulations though and which are apparently performing OK then this can't be a contributing factor.

As I implied earlier .... the INS in "each of" our panels/simulations that feature it is "identical" (it's programmed precisely the same way regardless of the panel/aircraft type), so, it's odd this should apparently impact just your CV-990A INS DC-8-62/63 INS panels only.

I'd be curious to know if you experience similar INS issues using the DC-8-50 INS, -61 INS, -71 INS, and 72/73 INS panels too .... though there's been no reports of any issues since the gauges files for these particular panels were last updated during 2018.

I'm going to leave this in Nathan's hands now .... since he's more familiar with our INS than I am.

Mark C
AKL/NZ

[Pedro]

Forgot to mention that I move the Aircraft in a cold and dark state, only after that I start to program the INS, with the DC-8 and all other Aircaraft.

I will try your sugestion with the DC-8-50, -61, -71 INS, and after I tell you something.

I´m not sure, I thing the problem is not the INS at all, I have two supicions, one is the A/P, because the CV-990A and DC-8 both have the same A/P gauge, or could be the KLN90 GPS that is sending some other information to the A/P, I´m not sure of this.

Thank you once again for your time and attention.

Cheers,

Pedro

[Pedro]

So, I follow your sugestion Mark, and prepared a flight with the DC-8-50, but something strange happen, after take off I flew the Plane manually and turn it towards Edwards AFB, then I turn on the A/P, but the A/P do not follow the INS instructions, I swich the A/P to HDG and follow Heading 240º and then 210º, and at about, 6 minutes (+-30-40NM, I´m not sure about the distance) from the first Waypoint, wich is a VOR called HECTOR, I turn the A/P into INS mode again, but this time the A/P follow the INS instructions precisely until I arrieved at KEDW.
This is really strange,and driving me crazy since a I do these Flight to test new HJG Planes with INS, but the DC-8 and Convair are the only ones wich the A/P makes some strange things and after a while it decides to follow the INS

Cheers,

Pedro

[Nathan Ford - HJG]

Hi Pedro,

I downloaded the Flying Tigers livery in FS2004 (FS9) and loaded up the sim. When you first load the same, always load a default aircraft first (I use the 182). I then changed aircraft and changed location to Nellie AFB. As there are no parking locations I used “Active Runway”.

I then taxied to a parking location (not using slew) and shut the aircraft down.

Once shut down, I shut down the INS unit (off).

Now I ran through the INS setup as per the tutorial using fast align, entering my current location into pos and the waypoints you provided. Once aligned I started the aircraft up and taxied to the active runway.

After takeoff and with the aircraft cleaned up and on autopilot heading mode, I then selected DIS/TIME WPT CHG and entered 0 and 1 into the From To window followed by INSERT.

I then set the autopilot to INS and she turned immediately to approximately 215 degrees and flew directly to the first waypoint in your flightplan. Approximately 100nm. At the moment, the aircraft has just changed direction to waypoint 2.

Can I make a couple of suggestions.

Firstly always start the sim with a default aircraft, never with a saved situation using an HJG aircraft.
Next, load the HJG aircraft fresh after loading the default plane, once again, don’t use a saved situation.
Remember to put the aircrafts current position into POS 0.
Once the INS is aligned, don’t use slew.
When you are ready to put the autopilot into INS, update the FROM TO using WPT CHG to 01 remembering to INSERT. This is important as you need to be close to being on course for the autopilot know where to go. (I can’t emphasise this step enough 😉)

From what I can see, you do have a proper understanding of the INS unit, but as I could not replicate your error there must be a small step that has slipped past you.

Maybe if you tried following the tutorial flight on the forum, but using the DC8-73F and see if that works.

Cheers and keep us posted. 🤓👍🏻

Nathan

p.s. One thing to also note, the INS on the two panels you mentioned doesn’t drive the HSI, it just drives the autopilot.

[Pedro]

Hi Nathan,

Sorry for my late reply.

Thank you very much for taking your personal time for helping me with this small issue.
I will start school this week and I have to study, in the next weekend I will make a flight following your sugestions and seed what will happen, then I´ll tell you something.
Thank you very much once again.

Cheers,

Pedro

[Nathan Ford - HJG]

All good Pedro, there is no rush, we understand that we all have busy personal lives.

Will get this figured out for you so you can get back to enjoying your flying again ☺️

Cheers,
Nathan

[Pedro]

Hi Nathan,

Sorry for making you wait so long.

I prepared a flight and folowed your sugestions and it worked perfectly, the Aircrfat followed the INS instructions, as soon as I turned the Autopilot on.
Thank you very much for taking from your personal time to help me with this small issue.

Cheers,
Pedro