Ralphk Posted August 13, 2020 Share Posted August 13, 2020 Hey folks i noticed that while engaging target with the jdam on a slant terrain my gbu is not hitting the spi and missing by 2 meters or so... what could be the reason? I am within release parameters... Sent from my SM-G950F using Tapatalk Link to comment Share on other sites More sharing options...
Frederf Posted August 13, 2020 Share Posted August 13, 2020 JDAM kills SPI so inaccuracy of JDAM is inaccuracy of SPI. What sensor is generating your SPI? Link to comment Share on other sites More sharing options...
Ralphk Posted August 13, 2020 Author Share Posted August 13, 2020 Tgp point lock on a bmp Sent from my SM-G950F using Tapatalk Link to comment Share on other sites More sharing options...
Frederf Posted August 13, 2020 Share Posted August 13, 2020 OK, TGP is calculating intersection of TGP LOS with DTSAS surface with assumption of A-10 EGI position. EGI position is perfect so this can be ignored. DTSAS surface is a database of terrain in memory which is similar but not exactly equal to actual terrain. Calculated intersection of TGP look direction and this surface is only approximately equal to intersection of this line of sight to actual terrain. Additionally vehicle is not in terrain database so it is not accounted for in calculation. Try to look at coordinate display on TGP page first without and then with laser rangefinder firing. You will see that coordinates under cursor are different with and without this laser range information. This is because target position calculation is now using TGP LOS and laser range instead of surface intersection. Try dropping a JDAM against the target while laser rangefinder is on and you will see improved accuracy. Link to comment Share on other sites More sharing options...
Ralphk Posted August 13, 2020 Author Share Posted August 13, 2020 Thx for the extensive information Sent from my SM-G950F using Tapatalk Link to comment Share on other sites More sharing options...
Nero_6 Posted August 14, 2020 Share Posted August 14, 2020 I think it's a new bug problem or something like that. I have the same problem: Last week I make my SPI with TGP and when i have the "MAN RELEASE" i release the bomb and always hit the target... Now, it's imposible. The bomb always falls 3 meters before... I must release the bomb when the indicator of the CCRP reticule it's in the half position. It's the only way to hit the target,... [sIGPIC][/sIGPIC] Link to comment Share on other sites More sharing options...
Emmy Posted August 14, 2020 Share Posted August 14, 2020 Pickling the split second the window opens has always led to at least some inaccuracy so a little patience won’t hurt. [sIGPIC][/sIGPIC] http://www.476vfightergroup.com/content.php High Quality Aviation Photography For Personal Enjoyment And Editorial Use. www.crosswindimages.com Link to comment Share on other sites More sharing options...
Ralphk Posted August 14, 2020 Author Share Posted August 14, 2020 Freferf to follow ur logic i indeed saw q difference in coordinates and i marked the spi while lasing and was subsequently able to hit the targets.. so basically the spi should be set while lasing. Sent from my SM-G950F using Tapatalk Link to comment Share on other sites More sharing options...
Frederf Posted August 14, 2020 Share Posted August 14, 2020 Yes that makes a more accurate SPI. Link to comment Share on other sites More sharing options...
Biga42 Posted August 17, 2020 Share Posted August 17, 2020 @Ralphk this video will help you: Link to comment Share on other sites More sharing options...
Ralphk Posted August 18, 2020 Author Share Posted August 18, 2020 Thx for the vid Sent from my SM-G950F using Tapatalk Link to comment Share on other sites More sharing options...
Ralphk Posted August 18, 2020 Author Share Posted August 18, 2020 I should be using the mark point it is a very handy tool on the battlefield Sent from my SM-G950F using Tapatalk Link to comment Share on other sites More sharing options...
DmitriKozlowsky Posted August 18, 2020 Share Posted August 18, 2020 Two meters off, is ON target. Anything within 50 meters is OK for JDAM. Within 10 meters is ON target. If you want to put a bomb into a manhole, use LGB. Link to comment Share on other sites More sharing options...
LastRifleRound Posted August 19, 2020 Share Posted August 19, 2020 Question: Since TGP becomes the designation source on TMS long up, does the range revert back to DTSAS when the laser stops firing, or does it keep the laser for slant range until the pod is slewed again? I usually set SPI with TMS Long up with the TGP as SOI, then briefly hold the lase button for a second or so, but I do not leave it on through the whole attack (and do not slew the pod again either. If I do, I re-lase when I'm done) Link to comment Share on other sites More sharing options...
LastRifleRound Posted August 19, 2020 Share Posted August 19, 2020 Two meters off, is ON target. Anything within 50 meters is OK for JDAM. Within 10 meters is ON target. If you want to put a bomb into a manhole, use LGB. JDAM WEZ when fully aligned on an aircraft with tightly coupled GPS is like 9m 50m is expected when GPS not tightly coupled, at least according to the Harrier documentation. I doubt the A10 is worse than this, and it certainly isn't off by that amount in DCS unless I do something wrong. You are right though, if it it's pinpoint accuracy you want, it's hard to beat an LGB, at least in DCS. Link to comment Share on other sites More sharing options...
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