Why does GBU-12 cruise?

[=4c=Nikola]

GBU-12 dropped from 32500ft with Mach 0.9 in ISA conditions has ballistic range of ~6NM.

 

GBU-12 dropped from 32500ft with Mach 0.9 in ISA conditions and target being lased has cruise range of more than 20NM.

 

Is that correct behavior?

 

I cannot believe that such a rudimentary control system gbu-12 has installed can increase range.

[Tenkom]

GBU-12 dropped from 32500ft with Mach 0.9 in ISA conditions has ballistic range of ~6NM.

 

GBU-12 dropped from 32500ft with Mach 0.9 in ISA conditions and target being lased has cruise range of more than 20NM.

 

Is that correct behavior?

 

I cannot believe that such a rudimentary control system gbu-12 has installed can increase range.

 

A bomb hits the ground with a significant amount of kinetic energy which could be used to increase the range in exchange for hitting the ground with less speed. However I agree that it seems excessive.

The gbu38 is especially bad in this regard. When you look at it in f6 view it seems to fly nearly horizontally for long periods time which seems impossible to me with my, admittedly, rather limited knowledge of physics and aerodynamics.

[VDV]

LGBs does not cruise, JDAM does ( I dont know how realistic is that BTW).

 

But you are in mistake anyways.

[Tippis]

LGBs does not cruise, JDAM does ( I dont know how realistic is that BTW).

 

But you are in mistake anyways.

LGBs certainly cruise in-game. This is an ancient issue, and no, he's not mistaken.

 

 

Note the publish date. Note the release altitude. Not the attitude of the mostly ballistic bombs.

[Dee-Jay]

I "doubt" that regular laser pods are powerful enough to ensure a good laser spot at FL300 / 20NM+ ... This is something for a good Wescam.

 

GBU-12 dropped from 32500ft with Mach 0.9 in ISA conditions and target being lased has cruise range of more than 20NM.

mmm ... that's not good "IMO".

Laser (and PII/III seeker) have some limitations (power/diffraction).

[VDV]

LGBs certainly cruise in-game. This is an ancient issue, and no, he's not mistaken.

 

 

Note the publish date. Note the release altitude. Not the attitude of the mostly ballistic bombs.

 

Sorry, but LGBs never "cruise" for me. I fly on Hornet. Only JDAM does.

[=4c=Nikola]

LBGs cruise in hornet as well.

[QuiGon]

Paveway I and Paveway II LGBs should not cruise/glide. The total opposite should be the case: When they start tracking they should bleed a lot of energy because of their bang-bang type control system that overcorrects a lot and thus bleeds a lot of speed.

Newer generation LGBs of Paveway III and above (e.g. GBU-24) are capable to glide/cruise AFAIK.

[Dunx]

I don't think Santa should be considered because, well, he really doesn't exist (?)

[Swift.]

I wonder if perhaps the gbu12 is seeking the end of the magic wand, which at 20NM wont be intercepting the ground at all. So it is infact seeking toward some point in the sky between the target and the plane, the same issue that allows laser mavs to be lofted manually.

[=4c=Nikola]

Paveway I and Paveway II LGBs should not cruise/glide. The total opposite should be the case: When they start tracking they should bleed a lot of energy because of their bang-bang type control system that overcorrects a lot and thus bleeds a lot of speed.

Newer generation LGBs of Paveway III and above (e.g. GBU-24) are capable to glide/cruise AFAIK.

 

Yea, that's exactly my reasoning.

[Tippis]

Yeah, there's a difference between gliding and steering along a ballistic path. The difference between the paveway variants is how effectively they do the latter; none of them can do the former… except the DCS ones do.

 

Something in their flight (or guidance) modelling give them extraordinary hang time if they have a target in view, as if being dragged along by the nose when they should rather be falling (and even still be accelerating) straight down and should long since have bled off most of their forward momentum.

[razo+r]

If you specate the bombs, you will notice that the G-meter shows 0Gs (unless the bomb corrects its flight path). Maybe this is where the weird thing is at?

[QuiGon]

One point, Paveway III and beyond cannot glide, the Paveway series is only able to follow a ballistic profile, yes newer generations are able to glide further due to the better control system QuiGon mentioned but they are unable to glide.

Absolutly right! :thumbup:

[Frederf]

This.

 

One point, Paveway III and beyond cannot glide, the Paveway series is only able to follow a ballistic profile, yes newer generations are able to glide further due to the better control system QuiGon mentioned but they are unable to glide.

 

Correction, Paveway III does glide. It's possible for PIII to climb above launch altitude. Paveway I and Paveway II are simplistic in their guidance by comparison.

 

Anyway, PII in DCS has oddly good behavior even during recent very shallow approach to target.

[Fri13]

R-27ER will drop as a stone at Mach 0.9 , but the GBU's will be perfectly gliding NOE at that release speed.

 

Irony....

 

The ballistics / aerodynamics for bombs doesn't work well in CS. It was already evident in the F/A-18C receiving the glide bombs etc when you can release them at the max range and the bombs will always find their way to the target. It is like perfect calculation for the release.

 

Instead IMHB that the release should be delayed much further than the earliest max range calculated, as the bombs likely will not make it otherwise. So if max range is 100% and minimum range is 30%, then the optimal release likely should happen between 80-40% instead 100-30%.

 

It is little like holding a missile launch button to be ready release missile as soon the maximum launch range is calculated for the given target, instead waiting little longer to improve the propabilities.

[Flamin_Squirrel]

Yeah, there's a difference between gliding and steering along a ballistic path...

 

I don't believe there is. ANY deviation from a ballistic path by very definition requires the application of lift. If you can generate lift, you can glide.

 

The discussion here should be revolving around the magnitude of the Paveway's gliding abiity, not whether it can or not.

[Notso]

GBU-12 dropped from 32500ft with Mach 0.9 in ISA conditions has ballistic range of ~6NM.

 

GBU-12 dropped from 32500ft with Mach 0.9 in ISA conditions and target being lased has cruise range of more than 20NM.

 

Is that correct behavior?

 

I cannot believe that such a rudimentary control system gbu-12 has installed can increase range.

 

I don't understand the question. Your release conditions are the same for the same weapon. Are you saying the GBU-12 went 20nm while being lased and only went 6nm while being dropped ballistically without the laser on?

 

The bottom line is, NO a GBU-12 cannot "cruise" for 20nm under any conditions.

[Notso]

Correction, Paveway III does glide. It's possible for PIII to climb above launch altitude. Paveway I and Paveway II are simplistic in their guidance by comparison.

 

Anyway, PII in DCS has oddly good behavior even during recent very shallow approach to target.

 

Thank you, I was about to post the same thing. The only thing I would add to that is that PWIIIs glide ONLY if they have laser guidance. Without, they fall ballistically until and if they see the laser spot.

 

For the rest of the group: It's important to understand that PWII are nothing more than dumb bombs with a seeker kit on the nose and guidance fins on the back. But ballistically they are essentially the same as their bomb body counterparts. i.e. the GBU-12 has roughly the same ballistics as a MK-82 LDGP. A GBU-10 ~ MK84 and so on. So for instance if you drop a GBU-12 and you either don't turn on the laser or the seeker fails for some reason - the bomb will hit roughly near the target just as if you dropped a Mk-82. WITH laser guidance, it's possible to "drag" the bomb long of the original designation point, but you will deplete its energy quickly and can only go so far before it runs out of energy and falls short. There definitely is no "glide or cruise" for PWIIs.

[Notso]

R-27ER will drop as a stone at Mach 0.9 , but the GBU's will be perfectly gliding NOE at that release speed.

 

Irony....

 

The ballistics / aerodynamics for bombs doesn't work well in CS. It was already evident in the F/A-18C receiving the glide bombs etc when you can release them at the max range and the bombs will always find their way to the target. It is like perfect calculation for the release.

 

Instead IMHB that the release should be delayed much further than the earliest max range calculated, as the bombs likely will not make it otherwise. So if max range is 100% and minimum range is 30%, then the optimal release likely should happen between 80-40% instead 100-30%.

 

It is little like holding a missile launch button to be ready release missile as soon the maximum launch range is calculated for the given target, instead waiting little longer to improve the propabilities.

 

Oh no! This is the ORP vs BRP argument :doh:

[Tippis]

I don't believe there is. ANY deviation from a ballistic path by very definition requires the application of lift. If you can generate lift, you can glide.

Nah, not when the steering isn't a matter of lift, but of differential breaking, which is more like what the early models employ. :P

 

The thing is, in DCS, GBUs can extend their glide by doing the very thing that by very definition should make them lose energy and reduce their range. This is, of course, not how they should be behaving. As demonstrated, they've been doing this for quite some time now.

 

 

The bottom line is, NO a GBU-12 cannot "cruise" for 20nm under any conditions.

Close. The bottom line is, YES a GBU-12 can “cruise” like that on the condition that they're being employed in DCS. That's sort of the whole issue.

[=4c=Nikola]

Are you saying the GBU-12 went 20nm while being lased and only went 6nm while being dropped ballistically without the laser on?

 

Yes

[randomTOTEN]

LGBs certainly cruise in-game. This is an ancient issue, and no, he's not mistaken.

 

 

Note the publish date. Note the release altitude. Not the attitude of the mostly ballistic bombs.

This user uploaded the track of the video in the comments section. I just downloaded it, and the aircraft crashes into the ground before pickle.

I took control and repeated the attack.. and they still travel horizontal to the target! COOL!!

 

 

I guarantee you the USAF tried this at some point during testing.:megalol:

[Flamin_Squirrel]

Nah, not when the steering isn't a matter of lift, but of differential breaking, which is more like what the early models employ. :P

 

The thing is, in DCS, GBUs can extend their glide by doing the very thing that by very definition should make them lose energy and reduce their range. This is, of course, not how they should be behaving. As demonstrated, they've been doing this for quite some time now.

 

 

 

Close. The bottom line is, YES a GBU-12 can “cruise” like that on the condition that they're being employed in DCS. That's sort of the whole issue.

 

I don't think so. A GBU can adjust its trajectory forward of its ballistic path, which it wouldn't be able to do if what you were saying were true.

 

Don't get me wrong the video you posted in post #4 doesn't look at all right, but if a bug is going to be reported it should be done right.

[Tippis]

Oh, don't worry. It has been done. Years ago. :D