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Navigation System Issues


pdmarsh
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In the attached mission, if I have the Viggen start hot and on the runway, the navigation system works perfectly. On autopilot, the aircraft will fly directly toward a given waypoint without any deviation. There is no need to press the reference button while on the runway or make a visual or radar fix in flight. My BX8 waypoint is directly over the target convoy on the radar screen.

 

However, if I start either hot or cold on the ramp, no matter what I do the navigation system never comes into alignment and the "Nav Syst" warning light comes on and stays on. I have tried using and not using the reference button after lining up on the runway from both directions and I have tried performing a visual waypoint fix in flight. Nothing solves the problem. On autopilot, the waypoint in question will drift to one side or the other requiring constant course correction. The BX8 waypoint is off to one side of the target convoy on the radar screen.

 

At first I thought I was doing something wrong in the cold start, but the hot ramp start showed that was not the case as the hot runway start works fine, but the hot ramp start does not.

 

For what is worth, tower communications are not working either and I have experienced a number or crashes to desktop while testing this mission. I have also experienced the issue of not being able to fire Rb-15 missiles after rearm. Search code 800001 seems to work in that multiple ships get targeted in a dual missile launch, but 800002 and 800003 do not seem to work.

 

It's a great module and I am looking forward to fixes to the various issues.

 

I hope this helps.

 

Paul

Dock Strike.miz

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Did you load the cartrige correctly? Did you insert it before? Are you in mastermode "NAV"

 

and pressing the reference button on runway is a thing you alwas should do.

 

For the tower communication, have you selected the correct frequency and special channel? Also make sure you have easy comms disabled.

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Make sure you are not turning on master mode NAV too soon. It should only be turned on when you are on the runway or very close to take off. I think 2 minutes is the maximum allowed time limit for NAV to be selected before take off. Also I've noticed that you don't really need to use the reference button on take off anymore, I think that was fixed. You can see the compass align itself during the take off roll around 150km/h or so if you don't use the reference button. I usually still use it just out of habit though.


Edited by Bullitthead
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Did you load the cartrige correctly? Did you insert it before? Are you in mastermode "NAV"

 

and pressing the reference button on runway is a thing you alwas should do.

 

For the tower communication, have you selected the correct frequency and special channel? Also make sure you have easy comms disabled.

 

Hi razo+r. In the case of the cold start, I am inserting the data cartridge at the time instructed in the checklist, after ground power is on and before anything else is done. I am also loading the data properly at the time instructed in the checklist. In the case of the hot starts, the cartridge is loaded for you and the data has been loaded as well. Yet, in the case of the hot ramp start, navigation is still not functioning properly. Mastermode NAV is not set until just before taxi or takeoff. Regarding tower comms, I have selected the correct frequency and easy comms is disabled. An interesting thing about the reference button is this, also associated with the cold start. After turning on NAV mode and lining up on the runway, the Nav Syst warning light is out. After I press the reference button, the warning light comes on and stays on. If I don't use the button and just take off, the warning light will come on after takeoff.

 

Thanks for the comments, but I am fairly certain there is a bug lurking here somewhere. It seems associated with this mission file, or possibly the airbase, as it has all worked well in a different training mission at a different starting base.

 

Paul

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Make sure you are not turning on master mode NAV too soon. It should only be turned on when you are on the runway or very close to take off. I think 2 minutes is the maximum allowed time limit for NAV to be selected before take off. Also I've noticed that you don't really need to use the reference button on take off anymore, I think that was fixed. You can see the compass align itself during the take off roll around 150km/h or so if you don't use the reference button. I usually still use it just out of habit though.

 

Hi Bullitthead. Thanks for your comments. I do wait to turn on NAV mode until just before taxi or takeoff. In a different mission I can see the compass snap into position when I press the reference button. It is a reassuring thing to see. In this mission, pressing the reference button after lineup makes the Nav Syst warning light come on and I do not get that nice snap of the compass. If I don't press the reference button, the Nav Syst warning still comes on, but only after takeoff.

 

I am beginning to suspect that the airbase itself might be the issue, or how data associated with the base is used by the Viggen. Starting up hot on the runway works perfectly. Starting up hot or cold on the ramp does not work at all with regard to navigation. I have not seen this issue in other training missions.

 

Thanks again,

Paul

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Make sure you are not turning on master mode NAV too soon. It should only be turned on when you are on the runway or very close to take off. I think 2 minutes is the maximum allowed time limit for NAV to be selected before take off.

 

Yeah, and this is because the engine is used to circulate coolant, and ground idle is not enough to cool the systems outside of BER mode. If you need NAV earlier than 2 mins before take-off, you can kick the throttle into flight idle and that should be fine (according to SFI).

Win10 x64 | SSDs | i5 2500K @ 4.4 GHz | 16 GB RAM | GTX 970 | TM Warthog HOTAS | Saitek pedals | TIR5

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I think that you are right Paul. It looks like an issue with Maykop airport. I just flew your mission and am having the same issue that you describe. I tried take off from both directions of the runway and I also deleted your Viggen group and created a new one with the same results. I found that if I move the take off location to Sochi everything works correctly. I also noticed that on the kneeboard, page 11, the description for the take off and landing waypoints is ?? instead of the airport name.

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I also noticed that on the kneeboard, page 11, the description for the take off and landing waypoints is ?? instead of the airport name.

 

Good catch, Bullitthead, I missed that. However, I meant to post that the landing waypoint takes you in a totally different direction, which seems to fit. One thing I am going to try is manually entering the airport code. I also need to see what code is used by the cartridge.

 

Thanks,

Paul

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OK, I found the root cause. Although it was self-inflicted, I'm not prepared to say there isn't something that needs to be fixed.

 

I placed a FARP within the confines of the airfield and placed the Viggen flight near that, but on the ramp of course. This was done for dramatic effect, i.e. seeing a flight of choppers land as you prep for flight. The data cartridge is using the code for the FARP, 9024, instead of the airfield code of 9005. If I delete the FARP from the mission, the problem goes away. When the plane starts on the runway, it is far enough away from the FARP for this to not be a conflict.

 

Using FARPs in this manner has been done before, but it appears to be a problem unique to the Viggen with its use of a data cartridge. I will try manually changing the code and see if that is a workaround for now.

 

So, warning to all, don't cross the beams, or something like that!

 

Paul


Edited by pdmarsh
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