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Blast Effects & Demolition

Blaster Power

Hand-held blasters--even pistols--can unleash searing concussive blasts when set to full power. The higher settings on a blaster can incapacitate or kill a person with shrapnel and shock from a near miss, or explosively blast apart hefty sums of rock, stone & metal. Maximally powered blasts are sparingly used on hand-held blasters because they deplete the blasters power source so quickly, and direct use of the blast setting upon organics is avoided. 


This article focuses on the use of blasters in a demolition type role: destroying hard targets composed of rock, stone & metal with explosive force. 

I have evaluated the explosive feats achieved by blasters in Star Wars using real-life empirically derived rules of thumb based on conventional explosives.


Galleries

Rock Blasting

Metal Blasting

Rock Blasting

Demolition of rock structures

During the waning hours of the second invasion of Geonosis, clone troopers used DC 15S blaster carbines to demolish structural support columns of rock in the successful attempt to collapse huge underground structures. These pillars were a meter (3 ft) wide in places.

R. McAdam and R. Westwater, Mining Explosives, Oliver and Boyd, 1958 provides the following rules of thumb for 'plaster shooting' rocky boulders:

Boulder Thickness (ft)
Explosive Charge (oz)
1 to 2
4
2 to 2½
8
2½ to 3
12
3 to 3½
16

So 1 pound (0.4545 kg) of explosive could be sufficient to demolish a 3 to 3.5 foot boulder of rock consistent in scale with the Geonosian columns. 

This quantity of TNT would correspond to 

Blast energy approx. 2 megajoules

Moreover, a structural column is under a considerable compressive load which tends to reduce the effectiveness of the explosive charge because it creates what miners refer to as a "tightly bound" situation

Mechanical engineer Mike Wong

The DC 15S carbine was used in another instance of ad hoc large-scale demolition when clone troopers blocked the entrance of some gundark dwellings, blasting hundreds of tons of rock to rubble and collapsing the structure. The troopers blasted an area of the cave in front of and above the visible opening from which the gundark was emerging. 

Photo of a gundark for scale; this creature is ~2.5 meters (8 feet) tall

A gundark lifts her entire body mass within the rocky abode

Former height / width / depth of the opening

The entrance is totally filled by hundreds of tons of blasted stone

Rock blasting in quarries is a highly developed technique in which the depth, diameter, and orientation of shot holes is critical to the effectiveness of the procedure, as well as the proper loading of each shot hole. However, given competent execution of all the aforementioned requirements, there are certain "rules of thumb" which one can use. The most basic rule is that the charge required for any given blasting operation and explosive type is directly proportional to the volume of the material to be blasted. In fact, one of the oldest methods of charge determination is to simply multiply the volume of rock by an "explosive coefficient" [3]. This may seem obvious or redundant, but it is nevertheless important to note that this prediction has been confirmed in practice throughout centuries of practical mining.


To be more specific, you can generally fragment somewhere between 4 and 6 tons of rock for each pound of high explosive used, and 3 to 4 tons of rock per pound of gunpowder [2]. But it should be noted that this ratio is based upon a highly optimized blasting pattern, with multiple shot holes drilled in various locations to distribute the shockwaves evenly throughout the rock face. Of course, this rule of thumb does not necessarily apply if the rock is of a highly unusual composition. Nevertheless, it is useful as a guide to the kind of energy necessary to fragment large volumes of rock if it is applied in the most efficient possible manner.

Explosives, stardestroyer.net, by mechanical engineer Mike Wong

So reducing a hundred tons of rock to fragments could be achieved using 25 pounds (11.3kg) of gunpowder, if the gunpowder was optimally distributed and strategically positioned for maximal efficiency. The energy released by one kilogram of gunpowder is ~3 megajoules, so the energy released by 25 pounds of gunpowder would be~34 megajoules


It took three troopers less than two seconds to blast the stone structure on Vanqor, and they discharged 14 bolts of energy from their blaster carbines during this time; this indicates per shot yields were in the megajoule range and that the blasters were set to blast for explosive effect. 

 

Wall Blasting

Demolition of masonry targets

Ultimate Star Wars mentions that the maximum setting on a DC 15A blaster long rifle can blast a half meter (1.64 ft) wide hole "through any ferrocrete wall" without specifying an upper limit on actual penetration. Ferrocrete is a composite material made from iron and concrete. 

From the venerable Guttmann text [3], we find some rules of thumb about destroying masonry or iron structures. In the case of masonry, Guttmann notes the longstanding rule of thumb that if you are using gelignite (low explosives being inappropriate for demolitions), the amount of charge required to destroy masonry walls can be computed from the rule-of-thumb formula L=0.1d², where L is the charge in pounds and d is the thickness of the wall in feet (this formula is not valid for walls thicker than 5 feet). In this case, the explosives are drilled into cavities spaced at twice the thickness of the wall. So to destroy a 2 foot thick wall, you would use 0.4lb charges of gelignite, drilled into tamped cavities spaced 4 feet apart.

stardestroyer.net: Explosives

 

Metallic Blasting

Demolition of metal targets

In the case of iron structures, substantially more explosive power is required relative to the volume of material to be broken up. Not only is iron much stronger than masonry, but the use of bore-holes or cavities is usually impractical so you must simply attach the explosives to the side of a the iron object to be destroyed. To destroy a cast-iron structural column, you would attach the charge to its base and tamp it as well as possible with dirt. The charge size would then be computed from the rule-of-thumb formula L=100d², where d is the diameter in feet and L is the charge of gelignite in pounds. Therefore, to destroy a six inch thick cast iron column, you would need to attach 25 pounds of gelignite: a very large and powerful explosive charge.

stardestroyer.net: Explosives

The RE factor of gelignite is 1.6

The energy density of TNT is 4.184 mJ/kg

Blast energy (or equivalent blast energy of TNT) will therefore be calculated by

E = 100d²u

Where E is blast energy in megajoules, d is depth & diameter in feet and u is 3.04, which is the energy in megajoules released by 1.6 pounds of TNT. 


Since there isn't real life experimental data using blasters I'll use this sum to approximate blast energy; this approximation is considered an order of magnitude estimate for gelignite or TNT, but it is very conservative for blaster bolts. This is in part because power--not just energy--is very important in determining the nature of explosive effects, so because dedicated explosives release their energy orders-of-magnitude faster than blaster bolts they are also more energy-efficient at generating explosive blast effects. This is not to say that a blaster bolt is incapable of generating explosive effects comparable to a dedicated explosive, only that the blaster bolt would need to expend greater energy to generate this type of effect. In the case of a blaster weapon any explosive effect is actually a secondary effect derived from the bolts interaction with a target. and the result of energetic thermal heating, melting and vaporization, which is why the explosive effect of a blaster bolt impact can be severely mitigated by sufficiently advanced armour where much less vaporization is allowed to occur. 

Blaster yield estimates on this page are therefore conservative. 

 

In Episode III  one clone trooper blasted a droideka in half and through the air with his DC 15A long rifle; the high-intensity bolts easily pierced the droids armour and the blast obliterated its entire abdomen, slamming its lower body into the ground and launching its upper body through the air. Though the bolt itself would have heated its way through the droid it was likely the ensuing explosion which blasted the droid apart. A droidekas metal abdomen is quite wide so it's not unreasonable to infer that the blast had to destroy more than 2.56cm or >1 inch of metal to blast the droid completely in half. 

Ofcourse the droid is both wider and deeper than just 2.56cm and this is a conservative estimate. 

Blast energy approx. 100*0.0833²u = 2 megajoules

In Episode IV when Luke, Han, Chewie & Princess Leia were pinned down due to suppressive fire by Imperial stormtroopers, Leia opened up an escape route by blasting a man sized hole through a large metal grate with an E 11 blaster carbine; the bars on this grate were approximately 25mm or one inch thick. In yet another example--this time from Episode I--an E 5 blaster carbine blows a B1 battledroid in half


Treating d as 2.56cm, 0.0833 ft or 1 cubic inch is clearly too conservative because so many examples show that blasters set to full blast intensity can blast through metal over a significant area. 

 

This droideka was violently blasted in half by a DC 15A long rifle

 
Leia's escape route through ~25mm metal
 

In A New Hope Luke Skywalker and Obi Wan Kenobi came across a wrecked sandcrawler which—by Kenobi's reckoning—had been blasted by small arms as he proclaimed “these blast points [...] only Imperial stormtroopers are so precise”, and pointed out the damages inflicted by “weapons bursts”.  

Leaving Luke to gape at the parallel sets of tracks, Kenobi turned his attention to the sandcrawler. 

He pointed out where single weapons' bursts had blasted away portals, treads, and support beams.


Star Wars Episode IV: A New Hope novelization

A sandcrawler is a 40 meter (131 ft) long--building sized--vehicle with thick metal walls, yet even one of these gargantuan machines was immobilised by pinpoint blaster fire, with some blasts destroying metal support beams and hatchways. The portal hatch could be scaled in the film; it was almost a foot thick and although it may not have been solid through all of this depth, these photos of the hatch do suggest it had at least 0.25 ft or 76 mm of solid depth. 

 

Sandcrawler portal hatch prior to destruction

 

Sandcrawler portal hatch post destruction

 

Blast energy approx. 100*0.25²u = 19 megajoules

In other words, single pinpoint shots destroyed entire support beams, and the support beams necessary for a vehicle of such great size would have to be enormously thick and strong. Even the act of destroying the huge treads alone would require heavy firepower; a modern soldier would be hard-pressed to do that kind of damage even with direct hits from a LAW or RPG. These men had no armoured vehicles; they were a "black ops" team, using dewbacks for mobility. The only weapons they had were the guns we saw them carrying, and with those guns, they were able to destroy a vehicle the size of a small apartment building.

Mechanical engineer Mr. Wong discussing blaster small arms and the Jawa sandcrawler

 

But blasted hatchways on a Jawa sandcrawler aren't the only examples implying the handheld blaster can wield metal-door-busting power. Later in A New Hope when Luke, Han, Chewie and Leia found themselves trapped in a trash compactor, the first thing Han did was attempt to blast away the metal bulkhead which was blocking their exit. He fired a single high powered bolt at the hatch but unfortunately the entire chamber was magnetically shielded, which prevented the doors destruction and caused the bolt to ricochet wildly around the room, reflecting from wall to wall. Luke clearly had similar expectations from his stolen E 11 blaster since he had already tried to blast the door down before Han had even arrived! 

George Lucas himself talked about "laser pistols" being used to destroy metal bulkheads twice in the fourth edition draft of A New Hope; this is Lucas's description of the trash compactor scene (note: Han fires at the hatch toward the left most side): 

LUKE

No! wait!


Han draws his laser pistol and fires at the hatch. 

The laserbolt ricochets wildly around the small metal room. Everyone dives for cover in the garbage as the bolt explodes almost on top of them. Leia climbs out of the garbage with a rather grim look on her face.


LUKE

Will you forget it? I already tried it.

It's magnetically sealed!

Jane Doe - Another Company, LLC

In the film Luke Skywalker opens the metal door guarding Princess Leia's cell using a button, however in both the novelization and the fourth edition draft by George Lucus it is said that he "blows the door away" using a blaster. In this case the film overrides the older scripts and the novel, and it is appropriate that Luke didn't try to blast the prison cell door for three main reasons: 

 

  • It could've been inhumane & dangerous to blast the bulkhead with Leia being so close to the door
  • A prison cell door could be more well armoured against small arms compared to other metal doors
  • There was a button to open the door

Luke stops in front of one of the cells and blasts the door away with his laser pistol. When the smoke clears, Luke sees the dazzling young princess-senator. She had been sleeping and is now looking at him with an uncomprehending look on her face. Luke is stunned by her incredible beauty and stands staring at her with his mouth hanging open.

Star Wars Episode IV: A New Hope
Fourth Edition draft by George Lucas

Both bulkheads were around two meters tall, a meter wide and composed of metal; even at the density of a relatively light metal--such as titanium--these doors would have weighed almost half a metric ton, or ~1,000 pounds. It could be inferred that both Luke Skywalker & Han Solo expected the higher settings on a blaster carbine to destroy half ton metal doors; the resulting destruction--had it occurred--might've been similar to the explosive breaching of the elevator door by Imperial stormtroopers. 

 

References

Data & Science

Stardestroyer.net's article on Explosives by mechanical engineer Mike Wong


R. McAdam and R. Westwater, Mining Explosives, Oliver and Boyd, 1958 - (rules of thumb for boulder and rock blasting)


Oscar Guttmann, Blasting: A Handbook For The Use Of Engineers And Others Engaged In Mining, Tunnelling, Quarrying, Etc, Charles Griffin and Co., 1906. - (rules of thumb for demolition of masonry & iron)

 

Feats

Star Wars: The Clone Wars - "Legacy of Terror" - (demolition of structural columns made from rock)


Star Wars: The Clone Wars - "Dooku Found" - (demolition of a large rock formation)


STAR WARS Episode I: The Phantom Menace


STAR WARS Episode II: Attack of the Clones


STAR WARS Episode IV: A New Hope