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GBU-8 HOBOS bomb


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The KMU-353 Homing Bomb (HoBo), also known as the Electro-Optical Guided Bomb (EOGB), received the GBU-8 designation in late January 1973, at the end of the Vietnam War. Although employed by F-4Ds during the war, it was not a very successful weapon, and I don't believe it remained operational long after the end of the war.

The HoBo was replaced by the GBU-15 Modular Guided Weapon system (MGWS), which began receiving designations in October 1974, although it didn't show up operationally until the mid-1980s. The MGWS did see limited service during Desert Storm and Allied Force, most notably being used to shut off Saddam's man-made oil spill into the Persian Gulf.

These kinds of bombs were extremely workload intensive both in terms of mission planning and employment and were only ever assigned to two-seat aircraft units (F-4, F-111 & F-15E), all of which were fast enough to provide the bombs with the energy they needed to glide to their targets. The A-10, having neither two seats nor excess energy never carried any of these weapons operationally, and I doubt the Air Force ever went to the expense to actually qualify them to be carried.

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These kinds of bombs were extremely workload intensive both in terms of mission planning and employment and were only ever assigned to two-seat aircraft units (F-4, F-111 & F-15E), all of which were fast enough to provide the bombs with the energy they needed to glide to their targets. The A-10, having neither two seats nor excess energy never carried any of these weapons operationally, and I doubt the Air Force ever went to the expense to actually qualify them to be carried.

thank you for the information Jim... I have one (in resin) of these bombs... so in which jet (and pylon) would you hang up it? Israeli F-4?

Edited by Alpagueur
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There are a number of publicity shots of a grey preproduction A-10A at Nellis with both GBU-10 and GBU-8 during their run up to operational service.

Edit: found some! - p. 30 of Squadron Signal's Aircraft In Action volume #1049, and halfway down here.

Cheers,

Andre

Edited by Andre
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These kinds of bombs were extremely workload intensive both in terms of mission planning and employment and were only ever assigned to two-seat aircraft units (F-4, F-111 & F-15E), all of which were fast enough to provide the bombs with the energy they needed to glide to their targets.

Just to amplify what Jim said, these bombs were glide weapons, which meant every time the flight controls were moved after release drag is created, energy bled off, and range shortened. As a consequence they were left on a ballistic path as long as possible, which meant that the bomb would "weather vane" into the prevailing winds for most of its flight time. As a result mission planning involved intensive study not only of the target but also study of the terrain features off to the side of the target, based on expected winds in the target area, and funneling features.

Regards,

Murph

Edited by Murph
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thank you for the information Jim... I have one (in resin) of these bombs... so in which jet (and pylon) would you hang up it? Israeli F-4?

The Hellenic Air Force still puts the GBU-8 on their updated F-4E Peace Icarus Phantoms.

Michael

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A_4_N_374_GBU_8_hobos.jpg

You know, I had forgotten about that! I have a friend who was an air attaché in Israel just after the Yom Kipper War (I think) and he told me about that. I actually built a 1:48 A-4 with that loadout--IIRC it had a late AN/ALQ-101 or early AN/ALQ-119 (long gondola but with no 'box' at the front) on one outboard wing station and an LAU-7/AIM-9G on the other. I think he said only two A-4 squadrons had that tasking--I think the one I did had kind of a flying tiger on a blue disk insignia, but I'm not positive about that. But I'm pretty sure they employed it during that war. Unfortunately, I didn't take any pictures of the model and it was crushed several years ago when workmen were installing a new heating system in my house. Long story, but they managed to destroy eight models. :(/> I think I still have the pieces--need to check the tail for the squadron markings.

Interesting comments above about the Greeks still (at least) displaying them on their F-4s. That's probably for air shows--it is pretty cool looking thing. I can't imagine anyone actually planning to use them at this point. My advice would be to choose a subject from the early to mid-1970s. If it is an F-4, mount it to the inboard pylons.

Edited by mrvark
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Does anyone know anything about the 'Stubby Hobo' version? It was used during the 1972 trails with the missile and bomb armed Firebee, the BGM-34A (the BQM-34A was the normal target Firebee). It wasn't just used as a show load, according to "Lightning Bugs' page 182 two of them hit the target, and a small photo shows an incoming 'Stubby Hobo'. Shown below are the two best photos of 'Stubby Hobo' that I know.

But that's about all I can find. I have never found the proper designation, or the weight, or any dimensions. A report titled 'Stubby Hobo Loads Analysis' by the Air Force Armament Lab (Eglin AFB) exists, but I cannot access it. I'm working on various models of the AQM-34 (here are my AQM-34L and M) and a BGM-34A is planned.

Does anyone know more?

bgm34a-01.jpg

bgm34a-02.jpg

Rob

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Interesting pics! I'd only ever seen a model of one. Here's what I know:

GBU-4/B & GBU-5/B

The GBU-4/B and GBU-5/B Lightweight, EOGB (LEOGB) were primarily intended for use with the BQM-34 RPV, but neither entered production. They were also linked officially with the A-7, F-111, F-4, and F-5, but never used by any of them. Both bombs adapted new warheads to the GBU-8's KMU-353A/B guidance kit.

Both warheads were developed by Project 5977, were assigned designations on 17 March 1972, and used 14-inch suspension. Shaped like truncated cones, they had a diameter of 15 inches at the front and 16 inches at the back to match the guidance kit.

The 99-inch long GBU-4/B's BLU-89/B blast/fragmentation warhead was 31.75 inches long. Its 0.25-inch thick steel case was filled with 175 pounds of Tritonal and held a 27-inch long, 0.125-inch thick Zirconium liner around the lower 270° of its circumference, which contained 5,400 132-grain (0.3-ounce) fragments.

The 100-inch long GBU-5/B's BLU-90/B shaped charge penetration warhead was 28.1 inches long. Its 0.33-inch thick aluminum and mild steel case was filled with 130 pounds of Comp B formed into a 13-inch diameter, 50° conical shaped charge. While the shape charge was its primary kill mechanism, the casing provided a secondary effect by exploding into 7,800 85-grain (0.2-ounce) fragments.

And, no, I can't explain why the bomb with shorter warhead was said to be longer...

Edited by mrvark
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Interesting pics! I'd only ever seen a model of one. Here's what I know:

GBU-4/B & GBU-5/B

The GBU-4/B and GBU-5/B Lightweight, EOGB (LEOGB) were primarily intended for use with the BQM-34 RPV, but neither entered production. They were also linked officially with the A-7, F-111, F-4, and F-5, but never used by any of them. Both bombs adapted new warheads to the GBU-8's KMU-353A/B guidance kit.

Both warheads were developed by Project 5977, were assigned designations on 17 March 1972, and used 14-inch suspension. Shaped like truncated cones, they had a diameter of 15 inches at the front and 16 inches at the back to match the guidance kit.

The 99-inch long GBU-4/B's BLU-89/B blast/fragmentation warhead was 31.75 inches long. Its 0.25-inch thick steel case was filled with 175 pounds of Tritonal and held a 27-inch long, 0.125-inch thick Zirconium liner around the lower 270° of its circumference, which contained 5,400 132-grain (0.3-ounce) fragments.

The 100-inch long GBU-5/B's BLU-90/B shaped charge penetration warhead was 28.1 inches long. Its 0.33-inch thick aluminum and mild steel case was filled with 130 pounds of Comp B formed into a 13-inch diameter, 50° conical shaped charge. While the shape charge was its primary kill mechanism, the casing provided a secondary effect by exploding into 7,800 85-grain (0.2-ounce) fragments.

And, no, I can't explain why the bomb with shorter warhead was said to be longer...

Jim, a big thanks for this information!! I quickly made a drawing using the drawing that comes with the Eduard Brassin GBU-8 and the photo where the GBU-4 or -5 is loaded on the BGM-34A. I copied the nose section and the tail section, added an aerodynamic fairing, and scaled the warhead from the photo using the fin chord. It's a vastly different thing now! I can't see the end of the aerodynamic fairing, but it gives a total length of somewhere between 94 and 100 inches. How does it look to you?

bgm34a-03.jpg

Rob

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A quick second version of the drawing, with the 'other' version included too. Plus I found a Teledyne-Ryan video

that showed roughly what the shape of the aerodynamic fairing was. Jim, do you have any idea which is which?

bgm34a-04.jpg

Rob

Edited by Rob de Bie
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A couple of F-4 GBU-8 pics from different eras and air forces:http://sistemasdearmas.com.br/pgm/gbu8kmu390.jpghttp://www.newsbeast.gr/files/1/2011/12/02/hoboslgb2.jpgJari

The thing to note on the Vietnam-era F-4D is that they spray painted the top quadrant of the bombs white. Ron Thurlow pointed this out to me--I think he found it in a report about the EOGBs. I think it was to aid in visually tracking the bombs as they went wherever they went--occasionally even to the target!

The pic of the Greek jet is fascinating--CLEARLY not an air show pic and the presence of the Litening pod (not to mention the gray camouflage) makes it clear that this is a pretty recent pic. I'm amazed that the things are still functional!

A quick second version of the drawing, with the 'other' version included too. Plus I found a Teledyne-Ryan video

that showed roughly what the shape of the aerodynamic fairing was. Jim, do you have any idea which is which?bgm34a-04.jpgRob

Excellent drawings, Rob! At this point you know as much about these bombs as I do. If I had to guess, I'd say that the top one is the GBU-4 and the bottom one the GBU-5.

Turkish Air Force actually used up some of its inventory of GBU-8 HOBOS in operations against the PKK (Kurdish separatists) in mid 1990s.

Interesting, isn't it that the Israelis, Greeks, and Turks all ended up with them?

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