Modular Guided Weapons System

[Yellow Palace]

The GBU-15/20 Modular Guided Weapons System turns out to be a lot more complex than I'd imagined. Like, a lot. Initially, no fewer than fifty-four configurations were envisaged, with various configurations of:

• Mark 84 or SUU-54 dispenser warheads
• Electro-optical, imaging IR, 'distance-measuring' (which seems to be inertial), or laser guidance - with two possible IR or laser modules!
• Three different wing configurations - the standard short-chord wings for direct attack only, expanded (i.e. long chord) wings for standoff and low-altitude delivery, and high-lift wings for range extension, which became the GBU-20.
• Options to add data links, distance measuring, and even LORAN

It also seems to have been expected to be a joint weapon, with different identification for the Navy wing kits due to the fuses being shipped with aerodybnamic surfaces. The quality of the scan from DTIC isn't great, but it also looks like it was considered as a defence suppresion weapon for SAC.

Interestingly, the details of six configurations, presumably including one missing guidance section and 'field-installed module', aren't shown in the configuration matrix. All of this came under the 'Pave Strike' programme, which also gave us the EF-111A, F-4G, and the TR-1 aircraft, as well as Pave Tack, laser and IIR Maverick, and a projected electronic warfare RPV.

https://apps.dtic.mil/sti/tr/pdf/ADA067594.pdf

 

[Scott Kenny]

Laser guided cluster bomb seems a bit odd, though I'd guess it was for the extended range kit and SEAD.

 

[Yellow Palace]

Laser guided cluster bomb seems a bit odd, though I'd guess it was for the extended range kit and SEAD.

Having done a bit more reading, I have a suspicion that one of the blanked out options in the weapon matrix is a SEAD version linked to the Precision Location Strike System.

 

[Dilandu]

Laser guided cluster bomb seems a bit odd, though I'd guess it was for the extended range kit and SEAD.

If you need to attack the area target - for example, an armor column - then it's a perfect solution. Standard "dumb" cluster bombs are very complicated to aim properly; pilot is forced to take into account not only the bomb ballistic, but the submunitions ballistic also (which means that he must not only calculate the dispersion point for the bomb, but also calculate the area when submunition would fell). With laser-guided bomb, the situation is much simpler.

 

[Hood]

Aiming was of dumb bombs was tricky, so many atmospheric variables at play. An updraught coming off a hillside sufficient to slow a retarded bomb's descent by 0.68 seconds was enough to cause a 70ft miss!

 

[Dilandu]

Aiming was of dumb bombs was tricky, so many atmospheric variables at play. An updraught coming off a hillside sufficient to slow a retarded bomb's descent by 0.68 seconds was enough to cause a 70ft miss!

Yep, and in case of cluster dumb bomb - the submunitions have their own behavior also, and react to the wind differently than the bomb itself.

 

[NMaude]

Yep, and in case of cluster dumb bomb - the submunitions have their own behavior also, and react to the wind differently than the bomb itself.

Being an area effect weapon I think that windage would be less of an issue.

 

[TomS]

Being an area effect weapon I think that windage would be less of an issue.

Still matters, hence the Wind-Corrected Munitions Dispenser (basically INS correction of the trajectory until dispense).

 

[Dilandu]

Being an area effect weapon I think that windage would be less of an issue.

No. Against armored targets you need the tight enough dispersion pattern, to ensure enough hits. So you want the center of pattern to be on target, not somewhere else.

 

[Yellow Palace]

Okay, so I was wrong about the DME guidance. Or rather, I was right, then decided I couldn't possibly be, so decided to be wrong instead.

It's not a form of inertial guidance. It's literally the distance-measuring equipment radio navigation system; there was some interest in it as a guidance system for missiles in the 1970s:

DME Surface to Surface Missile Demonstration System Analysis.

System design, analysis and tests were performed in preparation for a joint U.S. ArmyAir Force demonstration flight test. This flight test will involve use of the Air Force Advanced Location and Strikes System ALSS Distance Measuring Equipment DME navigation and guidance techniques for control...

apps.dtic.mil

Three-Beacon Projectile Guidance Study

The feasibility of employing an array of three ground-based beacons operating as distance measuring equipment DME transponders to accurately guide a projectile to a target is explored. For simplification of the problem, the projectile is assumed to be a point mass, with only drag, gravity and...

apps.dtic.mil

That sounds weird, which is why I'd initially dismissed it, but actually makes some sense. There's a line of development through Oboe, Gee-H, and SHORAN - all initially used for precision bombing - to the DME system.

It also makes a bit of sense of the proposed configurations with LORAN - the two radio-navigation systems look to have been mutually exclusive. AFAIK, radio-navigation has never been used for an operational air-launched weapon system.

There seem to have been some DME-only configurations envisaged, suggesting that it was expected to offer sufficient accuracy for unitary (not just dispenser) warheads.

One of the laser-guided configurations is specifically identified as being associated with the SCANA program, which I mentioned in the F-111 thread.

The 1984 Weapons File also identifies a range of possible exciting ways to maim one's enemies with the SUU-54 dispenser warhead:

• BLU-63 and BLU-86 fragmentation bomblets
• BLU-97 combined effects bomblets
• BLU-91 and BLU-92 air-delivered mines
• BLU-106 anti-runway projectiles

The CBU-75, carrying fragmentation bomblets, seems to have been the primary intended load, mostly for defence suppression. This actually was deployed with a Paveway I guidance kit as the GBU-2, sometimes called Pave Storm.

 

[Scott Kenny]

The 1984 Weapons File also identifies a range of possible exciting ways to maim one's enemies with the SUU-54 dispenser warhead:

• BLU-63 and BLU-86 fragmentation bomblets
• BLU-97 combined effects bomblets
• BLU-91 and BLU-92 air-delivered mines
• BLU-106 anti-runway projectiles

The CBU-75, carrying fragmentation bomblets, seems to have been the primary intended load, mostly for defence suppression. This actually was deployed with a Paveway I guidance kit as the GBU-2, sometimes called Pave Storm.

Now I have a need to build a couple F-4G Wild Weasels with strange weapons mixes...