New “maximum 10m guidance error” on GNSS is silly

[Sternlos]

IDK im no labcoat scientist but if the things guiding the bombs are in orbit around earth I don’t think they care where the plane is that dropped them.

[tripod2008]

@Sternlos

I don’t think they care where the plane is that dropped them.

(ignoring the influence of GPS satellites and complexities of how the constellation(s) impact accuracy)They would be by dint of the fact the errors in the INS simply have less time to accumulate over a shorter time of flight, also 10 meters far overestimates western ordnance which have CEP’s of 3 meters if they retain GPS connectivity.

[Sternlos]

@tripod2008

They would be by dint of the fact the errors in the INS simply have less time to accumulate over a shorter time of flight

That makes sense, see I really am not a scientist )))

What was sat bombs margin of error before it was changed to 10m? And where did gaijin decide to pull that number from.

[SilentTracker]

It was lowered to something like 5m a patch or two ago. It’s not 10m anymore. Will find patch notes in a bit. In a match right now.

EDIT: Patch notes posted below: New “maximum 10m guidance error” on GNSS is silly - #11 by SilentTracker

[vKALiBUR]

@Sternlos

What was sat bombs margin of error before it was changed to 10m?

is was “pin-point” accurate. I don’t believe anything was sourced in the changelog/devblog idk what it was.

[tripod2008]

@Sternlos

What was sat bombs margin of error before it was changed to 10m

Probably zero IIRC, simply because it can be hard to find numbers for the large variety of guided ordnance that has been added to the game.

Which is further complicated by the fact that as a statistical measure is a very large difference between the qualitative implications of a CEP50(%) vs a CEP80(%) or a accuracy value.

As they bound things differently. and further pending Gaijin’s implementation can make things annoyingly complex to actually measure.

[AlvisWisla]

It’s not 10 meters in-game currently anyway.
It’s currently 5 meters for most NATO GPS weapons.

[Ion_492]

They should just revert the change since it’s a net negative. However if they revert it, SPAA players will moan that CAS can kill them if they stay stationary too long.

It’s dumb to nerf stuff because it could be decent in one mode, without considering other modes like ARB or sim.

[vKALiBUR]

can someone post the devblog etc. where it says it was changed to 5m? edit: acc to AF.mil, “initial operational testing conducted in 1998 and 1999. More than 450 JDAMs were dropped during this testing, recording an unprecedented 95 percent system reliability while achieving a 9.6-meter accuracy rate.” They later say, “Growth of the JDAM family of weapons expanded to the MK-82 500-pound version, which began development in late 1999. Enhancements such as improved GPS accuracy…are being demonstrated and tested for future consideration.”

[SilentTracker]

@vKALiBUR

The Leviathan’s update changed a fundamental game mechanic resulting in GNSS munitions receiving a guidance error of “up to 10m”.

@AlvisWisla

It’s not 10 meters in-game currently anyway.
It’s currently 5 meters for most NATO GPS weapons.

@vKALiBUR

can someone post the devblog etc. where it says it was changed to 5m?

Patch that lowered it to between 7m and 5m, depending on ordinance. See very bottom quote for details: Update 2.47.0.47

@SilentTracker

@Stona_WT

The CEP (Circular error probable) for munitions with GNSS guidance has been reduced according to the known data.

Thank you. But by how much?

Reply from another player with details:

@Horizon333

50 kg KAB-50S, 250 lbs GBU-39A/B, 500 lbs GBU-38(V)1/B, 500 lbs GBU-38(V)2/B, 500 lbs GBU-62/B (JDAM-ER), 1000 lbs GBU-32(V)1/B, 1000 lbs GBU-32(V)2/B, 2000 lbs GBU-31(V)1/B, 2000 lbs GBU-31(V)2/B, 2000 lbs GBU-64/B:
position error: 10 → 5 m

125 kg GBU-58/B, 250 kg AASM 250 (SBU 64), 250 kg GB250 (GB3), 500 kg AASM 500 (SBU 56), 500 kg AASM 500 (SBU 66), 1000 kg GB1000 (GB5), Kh-38ML, Kh-38MT:
designation error: 10 → 7 m

250 kg AASM 250 (SBU 38), 250 kg LS-6, 500 kg FAB-500-M62 s UMPK, 500 kg LS-6, 500 kg UPAB-500B, 1500 kg UPAB-1500B, 3000 kg FAB-3000 s UMPK, Kh-36 Grom-1, Kh-36 Grom-2:
position error: 10 → 7 m

250 kg AASM 250 (SBU 54):
position error: 10 → 7 m
designation error: 10 → 7 m

250 kg KAB-250LG, 250 lbs SPICE 250, 500 lbs GBU-49(V)1/B, 500 lbs GBU-54(V)1/B, 500 lbs GBU-54(V)2/B, 500 lbs GBU-62(V)1/B (LJDAM-ER), 500 lbs Paveway IV, 1000 lbs GBU-48(V)1/B, 1000 lbs SPICE 1000, 2000 lbs GBU-24E/B, 2000 lbs GBU-50/B, 2000 lbs SPICE 2000:
designation error: 10 → 5 m

[Sternlos]

There isnt many places to hide these garbage trucks on a lot of maps.

I dont think its so bad with glide bombs as you at least have to climb or pop up and expose yourself if even briefly, but stuff like the kh38 that can be fired from the airfield without any LOS is still pretty lame. Combined with the follower camera and ground map a good cas player can just sit on their airfield and being a weird artillery piece that shoots exploding scout drones.

[vKALiBUR]

I think my point still stands that

@tripod2008

INS simply have less time to accumulate over a shorter time of flight

so the accuracy should be better the closer to the target.

[Xeno_quaza]

JDAMs IRL lack inertial guidance, so it makes sense that they have the same target deviation from any drop distance, as the accuracy of where they are aiming will always be off.

(IRL, several countries have worked on combined GNSS/Inertial systems to reduce this effect.)

[vKALiBUR]

@Xeno_quaza

JDAMs IRL lack inertial guidance

INS definition: In the context of bombs and munitions, INS stands for Inertial Navigation System.

https://www.af.mil/About-Us/Fact-Sheets/Display/Article/104572/joint-direct-attack-munition-gbu-313238/

Guidance System: GPS/INS

[Xeno_quaza]

Huh, odd, i have JMOD documents talking about them that says they don’t have it?

Assuming they do have INS, then yeah they should be more accurate closer to the target to a certain amount, although not as linearly as you’d see in other kinds of bombs.

[tripod2008]

@Xeno_quaza

JDAMs IRL lack inertial guidance

They absolutely do, use a GPS/INS system.

https://trace.tennessee.edu/cgi/viewcontent.cgi?article=3487&context=utk_gradthes

[Xeno_quaza]

Okay, odd, no idea why the documents i have say it doesn’t. They’re not dedicated JDAM documents so I guess they’re wrong, it’s still odd that they’re wrong.

[vKALiBUR]

out of curiosity, may we see your documents from the JMOD?

[Xeno_quaza]

Uh yeah lemme find it, it was some thing talking about developing innertial + GPS guidance systems

[SilentTracker]

@tripod2008

They absolutely do, use a GPS/INS system.

It would be really nice to be able to drop GNSS bombs without using a targeting pod too! (And/or without using a targeting point etc.)