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What would work without GPS?


No1sonuk

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There are currently no restrictions on putting modern aircraft, such as the A-10C, into historical scenarios that are dated before GPS existed.
So my question is ; What would still work without a GPS signal?
Obviously GPS-guided weapons wouldn't work, but assuming the digital ground mapping data is valid, would the TGP ground position hold still work off INS data?

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JDAMs for sure have INS only guidance as well, which would work in a GPS denied environment but the CEP would be much higher. This isn't simulated in DCS. The TGP should have an Inertial Sensor Unit, which would allow it to calculate seeker position relative to the aircraft's position. I can't say for sure whether a working INS would be required for this or not but if the INS is working, the stabilization should work for sure. Moreover, the TGP has some kind of 'pixel magic' to compensate and retain a stable track when it's ground stabilized.

 

Obviously the apparent limitation when it comes to these ops is INS drift. If the position drifts, not only will you have issues like waypoints not being where they should be, but since the jet can use DTED for A2G ranging, if the position information is inaccurate, that could in theory invalidate the CCIP solution, since it's calculating the range based on incorrect positional data. This isn't simulated in DCS, the INS doesn't drift and the update functions don't actually do anything.

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Everything other than the GBU-31/38/54 would be useable as normal. TGP would still work but it'd give you bad coordinate data, and punching good coordinates into the jet would send the TGP to the wrong spot. Also any mark points or steerpoints you make would drift with the INS.

There's a way to correct the drifting symbology by updating based off of known locations, but I don't know if that's simulated.

The JDAMs wouldn't necessarily be completley off the table, but I'm not sure to what level CDO stuff is simulated in DCS if at all and that gets into a lot of beeps and squeaks. Suffice to say you'd have to be careful about how you use them and if you knew you wouldn't have GPS at all on a sortie it'd probably be better to pick different weapons for your loadout.


Edited by ASAP
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1 hour ago, ASAP said:

There's a way to correct the drifting symbology by updating based off of known locations, but I don't know if that's simulated.

 

Only the F-18 has some kind of INS drift simulation out of the ED modules but that's also very, very far from being realistic. The A-10 doesn't simulate these procedures.

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Are we talking about "GPS restricted environment" or "historical scenarios"?

If latter - most of these weapons wasn't in service yet. Including A-10C itself, which was introduced in 2005. There was no TGP, JDAMs, no CBU WCMD....

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Everything works to some extent. Every "GPS" weapon is an "INS weapon which can incorporate GPS when available for improved performance." The airplanes also have the same behavior, INS with GPS for improved performance when available. Every piece of US military equipment is designed to function in the absence of GPS, just with a bit less performance due to not getting common position updates.

JDAM for example doesn't even connect to GPS during short flights. It takes too long which is why the precision improves the longer it's in the air. JDAM works fine. It's an INS weapon. Your miss distances might be 10m instead of 3m but you can still use it.

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3 hours ago, Frederf said:

Everything works to some extent. Every "GPS" weapon is an "INS weapon which can incorporate GPS when available for improved performance." The airplanes also have the same behavior, INS with GPS for improved performance when available. Every piece of US military equipment is designed to function in the absence of GPS, just with a bit less performance due to not getting common position updates.

JDAM for example doesn't even connect to GPS during short flights. It takes too long which is why the precision improves the longer it's in the air. JDAM works fine. It's an INS weapon. Your miss distances might be 10m instead of 3m but you can still use it.

THIS!

I'm a bit suprised how many people think, that such military equipment is entirely dependend on such a fragile technology like GPS, which can be easily spoofed or knocked out in case of peer to peer conflict. Pretty much all nav systems in modern military aircraft (and weapons as well) are still based on the good old INS tech, which just gets aided by GPS if available, but still works the same if GPS is not available. It just doesn't recive updates through GPS in that case and it's up to the pilot to do nav fixes, just like in the old days before GPS became a thing (before the mid 90s). Obviously it's not as precise without GPS support, but everything still functions (like TGPs and such).

Now in regards to DCS, this is only somewhat simulated in the Hornet (can drift and perform nav fixes) and I think to a lesser degree in the F-16 (can drift but is not able to do nav fixes yet). The A-10C on the other hand has no such GPS degraded simulation in DCS and works just the same with or without GPS.


Edited by QuiGon

Intel i7-12700K @ 8x5GHz+4x3.8GHz + 32 GB DDR5 RAM + Nvidia Geforce RTX 2080 (8 GB VRAM) + M.2 SSD + Windows 10 64Bit

 

DCS Panavia Tornado (IDS) really needs to be a thing!

 

Tornado3 small.jpg

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15 hours ago, Foka said:

Are we talking about "GPS restricted environment" or "historical scenarios"?

If latter - most of these weapons wasn't in service yet. Including A-10C itself, which was introduced in 2005. There was no TGP, JDAMs, no CBU WCMD....

Both.
Think of a "Final Countdown" type situation.

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On 1/5/2022 at 11:26 AM, QuiGon said:

Now in regards to DCS, this is only somewhat simulated in the Hornet (can drift and perform nav fixes) and I think to a lesser degree in the F-16 (can drift but is not able to do nav fixes yet). The A-10C on the other hand has no such GPS degraded simulation in DCS and works just the same with or without

This applies to ED modules though. Back in the old days of BS2, the Shark had INS drift but IIRC after several core updates changed how the maps and the coordinates work in the engine, these functions were never re-added. Other modules like the Viggen, the JF-17, the Mirage and the Tomcat not only have navigation drift but have simulated fixes and updates as well.

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37 minutes ago, WobblyFlops said:

This applies to ED modules though. Back in the old days of BS2, the Shark had INS drift but IIRC after several core updates changed how the maps and the coordinates work in the engine, these functions were never re-added. Other modules like the Viggen, the JF-17, the Mirage and the Tomcat not only have navigation drift but have simulated fixes and updates as well.

Indeed, although I thought that drifting for the Shark was only present in BS1 but never in BS2. I might be wrong though, it's been a while :smile:


Edited by QuiGon

Intel i7-12700K @ 8x5GHz+4x3.8GHz + 32 GB DDR5 RAM + Nvidia Geforce RTX 2080 (8 GB VRAM) + M.2 SSD + Windows 10 64Bit

 

DCS Panavia Tornado (IDS) really needs to be a thing!

 

Tornado3 small.jpg

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