ARL‐TN‐0676 ● MAY 2015

US Army Research Laboratory

Achieving 5‐μs Simultaneity of 36 RP‐80

Detonators

by Barry L Hudler, Eric W Miller, and Jarid M Kranz

Approved for public release; distribution is unlimited.

  
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ARL‐TN‐0676 ● MAY 2015

US Army Research Laboratory

Achieving 5‐μs Simultaneity of 36 RP‐80

Detonators

by Barry L Hudler and Eric W Miller

Weapons and Materials Research Directorate, ARL

Jarid M Kranz

Bowhead Science and Technology, LLC

Approved for public release; distribution is unlimited.
ii 

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May 2015 

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Technical Note 

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1 October 2013–30 April 2014 

4. TITLE AND SUBTITLE

Achieving 5-μs Simultaneity of 36 RP-80 Detonators 

5a. CONTRACT NUMBER

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6. AUTHOR(S)

Barry L Hudler, Eric W Miller, and Jarid M Kranz 

5d. PROJECT NUMBER

AH80 

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US Army Research Laboratory 

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Aberdeen Proving Ground, MD 21005-5066

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ARL-TN-0676

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12. DISTRIBUTION/AVAILABILITY STATEMENT

Approved for public release; distribution is unlimited. 

13. SUPPLEMENTARY NOTES

14. ABSTRACT

The US Army Research Laboratory investigated the conditions and the materiel required to fire large numbers of RP-80 

detonators simultaneously using the FS-43 firing system. The results of the investigation demonstrated an in-house capability 

for initiating 36 detonators within a 5-s simultaneity interval. 

15. SUBJECT TERMS

multiple detonators, FS-43, RP-80, simultaneous detonation, firing system 

16. SECURITY CLASSIFICATION OF:

17. LIMITATION

OF ABSTRACT

UU 

18. NUMBER

OF PAGES

42 

19a. NAME OF RESPONSIBLE PERSON

Barry L Hudler 

a. REPORT

Unclassified

b. ABSTRACT

Unclassified

c. THIS PAGE

Unclassified

19b. TELEPHONE NUMBER (Include area code)

410-278-7291 

Standard Form 298 (Rev. 8/98) 

Prescribed by ANSI Std. Z39.18 
iii 

Contents

List of Figures iv

List of Tables v

Acknowledgments vi

1. Introduction 1

2. Background 1

3. Experimental Setup and Firing Matrix 4

4. Experimental Results for a Single Firing System 7

5. Experimental Results for 2 Separate Firing Systems 14

6. Conclusions 22

7. References 23

Appendix A. Manufacturer‐Supplied Information Sheet on the FS‐43 25

Appendix B. Manufacturer‐Supplied Information Sheet on the RP‐80 29

Appendix C. Manufacturer‐Supplied Chart and Discussion Points

regarding Series‐Parallel Firing of EBW Detonators 31

List of Symbols, Abbreviations, and Acronyms 33

Distribution List 34
iv 

List of Figures

Fig. 1 Transfer box configuration for one FS-43 firing system and one RP-80 

detonator (shot 1) ......................................................................................2

Fig. 2 Fixture used for detonator-only experiments ...............................................5

Fig. 3 View of fixture with camera bombproof in background .............................5

Fig. 4 Successive video frames for shot 1 at 0, 5, and 10 s (left to right) ...........7

Fig. 5 Transfer box configuration for shot 2 ..........................................................8

Fig. 6 Successive video frames for shot 2 at 0, 5, and 10 s (left to right) ...........8

Fig. 7 Transfer box configuration for shot 3 ..........................................................9

Fig. 8 Successive video frames for shot 3 at 0, 5, and 10 s (left to right) ...........9

Fig. 9 Transfer box configuration for shots 4–7 ..................................................10

Fig. 10 Successive video frames for shot 5 at 0, 9, and 18 s (top to bottom) ....11

Fig. 11 Successive video frames shot 6 at 0, 6.25, 12.5, and 18.75 s (top to 

bottom) ....................................................................................................12

Fig. 12 Transfer box configuration for shots 8 and 9 ..........................................13

Fig. 13 Successive video frames for shot 8 at 0, 6.25, 12.5, and 18.75 s (top 

to bottom) ................................................................................................14

Fig. 14 Successive video frames for shot 10 at 0, 6, 12, and 18 s (top to 

bottom) ....................................................................................................15

Fig. 15 Successive video frames for shot 12 at 0, 6.25, 12.5, and 18.75 s 

(top to bottom) ........................................................................................16

Fig. 16 Successive video frames for shot 13 at 0, 6.25, 12.5, and 18.75 s 

(top to bottom) ........................................................................................17

Fig. 17 Successive video frames for shot 14 at 0, 6.25, 12.5, and 18.75 s 

(top to bottom) ........................................................................................18

Fig. 18 Successive video frames for shot 15 at 0, 6.25, 12.5, and 18.75 s 

(top to bottom) ........................................................................................19

Fig. 19 Successive video frames for shot 16 at 0, 6.25, 12.5, and 18.75 s 

(top to bottom) ........................................................................................20

Fig. 20 Side view of 33 Comp B modular charge setup. (Photograph courtesy 

of Dr Muge Fermen-Coker.) ...................................................................21

Fig. 21 Top view of 33 Comp B modular charge setup. (Photograph courtesy 

of Dr Muge Fermen-Coker.) ...................................................................22
v 

List of Tables

Table 1 Physical properties and resistance of firing lines of interest ....................4

Table 2 Experimental firing matrix ........................................................................6

Table 3 High-speed camera settings at 1-μs exposure time ...................................7
vi 

Acknowledgments

 Mr Kenneth Willan, US Army Research Laboratory (ARL), for providing 

the concept and equipment setup for simultaneously triggering the 2 FS-43 

control units using a break box. 

 Mr William Aubry, Bowhead Science and Technology, LLC, on-site at 

ARL, for providing useful physical and electrical property information for 

the different firing lines that either were used or were relevant to the 

experiments. 

 Dr Muge Fermen-Coker, ARL, for providing specific guidance for the 

modular lethality studies within ARL’s Scalable Effects Program. 

 Mr Jason Talsma, ARL, for providing the primary technical review. 

 Mr Bernard J Guidos, ARL, for providing additional report content and 

additional technical reviews. Mr Guidos also served as the coordinator for 

an ad hoc Firing Line Advisory Group consisting of the following 

personnel: Barry Hudler, Eric Miller, Jason Talsma, Richard Summers, 

Robert Frey, Richard Benjamin, Robin Strickland, Dr Brian Roos, Dr 

Kevin McNesby, Dr Muge Fermen-Coker, William Aubry, Kenneth 

Willan, John Heath, Jim Varosh (Teledyne), and Robert Reynolds (RISI). 
1 

1. Introduction

Experiments were recently conducted at the US Army Research Laboratory 

(ARL) Transonic Experimental Facility (TEF) in which 36 RP-80 detonators were 

initiated in a 5-s interval. The experiments were conducted in support of 

modular lethality studies within ARL’s Scalable Effects Program. The 5-s 

simultaneity interval was established as a requirement to avoid predetonation 

interference between adjacent Comp B modular charges and was based on the 

expected travel times of the detonation wave fronts. 

Preliminary discussions with scientists, engineers, and technicians within ARL 

indicated that previous in-house experiences with simultaneous detonation 

experiments consisted of, at most, several detonators. As such, the initiation 

circuit for 36 detonators represented a novel in-house application, possibly with 

complexity and constraint beyond that of a circuit for several detonators. To 

establish a level of reliability in the 36-detonator initiation circuit and to verify 

that the spontaneity and non-interference requirements were being satisfied, a 

series of detonator-only experiments was conducted. The detonator-only 

experiments preceded a successful simultaneous detonation of 33 Comp B 

modular charges in close proximity. 

This technical note describes details and results of the detonator-only 

experiments, with focus on the detonator initiation circuit and associated 

considerations. Notable aspects of the initiation circuit configuration and 

performance are described that may serve as a useful reference for future 

simultaneous detonation experiments. 

2. Background

RP-80 detonator initiation has been performed at TEF and other ARL 

experimental facilities for many years. At TEF, the typical experimental 

application involving detonation initiation uses a RISI FS-43 firing system (which 

consists of a control unit and a firing module) and 1 or 2 RISI RP-80 exploding 

bridge wire (EBW) detonators. Appendixes A and B are manufacturer’s 

information sheets on the FS-43 and RP-80, respectively. The RISI FS-43 uses a 

low-voltage 3-pair wire as the permanent firing line (from control unit to firing 

module). The initiation circuit for ARL in-house detonation experiments follows a 

baseline configuration as prescribed in ARL Standard Operating Procedure (SOP) 

385-008.1
2 

Figure 1 is a copy of illustration 3 from SOP 385-008 that shows the transfer box 

configuration (in the “safe” position) between the FS-43 control unit and a single 

RP-80 detonator. The transfer box contains the FS-43 firing module and 3 knife 

switches. The transfer box is typically located within an uninhabited bombproof 

or behind a barricade in close proximity to the explosive event, while allowing the 

control unit to be emplaced at the operator location much farther away. This 

configuration represents that which was used for shot 1 in the firing matrix for a 

single detonator. (Important note: Approved initiation circuits at ARL for 

intentional detonations include the RISI FS-43 and Cordin Model 640 High 

Energy Pulser. Information contained in this report will not correlate to multiple 

detonator use with the Cordin model.) 

Fig. 1 Transfer box configuration for one FS-43 firing system and one RP-80 detonator 

(shot 1) 

Basic considerations for this experiment included firing line length and type, both 

of which affect the rise time of the applied voltage. With a proper rise time (less 

than 3 s), RP-80s can be expected to fail at a rate of 1 in 1,000. A rise time 

greater than 3 s can be expected to produce a significantly higher detonator 

failure rate. 

Technical representatives from Teledyne RISI Inc. (manufacturer/supplier of the 

FS-43 firing systems and RP-80 EBW detonators) were contacted to obtain 

information and insight regarding multiple-detonator applications using their 

products. They supplied a standard 1-page information sheet entitled “Series 

Parallel Firing of EBW Detonators”, which is included herein as Appendix C. The 
3 

information sheet included a chart showing the recommended maximum number 

of RP-80 detonators that can be reliably initiated on each leg of a series-parallel 

circuit using the FS-43 firing system, as well as some precautionary 

recommendations. 

The information sheet was used as a basis for initially determining some 

configuration options that could be expected to provide the necessary voltage and 

simultaneity for 36 detonators. For the experiments described herein, the length of 

the replaceable firing line between the transfer box and detonator(s) was firmly 

established as 50 ft. The configuration that was explored and eventually adopted 

for initiating 36 detonators was the use of 2 separate FS-43 systems, each 

providing initiation voltage for 18 detonators. 

The information sheet was based upon certain materiel and/or conditions that 

were not duplicated in the actual experimental setup. For example, the length of 

blasting wire in the chart does not account for the presence of knife switches, 

which can introduce inductance as well as uncertain additional effective firing 

line length. 

Another example of a condition not duplicated in the experimental setup was the 

type of replaceable firing line upon which the chart is based. The chart refers to 

RISI twin-lead blasting wire (part number 167-8559) and RISI “C” cable (part 

number 162-2669); whereas the experiments were begun using RG-58 multistrand 

coaxial wire and completed using Belden 8470-063 black and white (B/W) 

twisted pair of single, insulated, 16 American wire gauge (AWG) lines. 

Eventually, the B/W twisted pair wire was adopted and used to initiate the 

33 RP-80 detonators for the full-up 33 Comp B module test. 

Table 1 shows manufacturer-stated resistance and some physical properties of the 

4 types of wire of interest. In addition to their resistance, the main differences in 

these 4 different types of firing lines are based upon their expense, ruggedness, 

and insulation. RISI C cable, the most expensive and most rugged, is used at 2 

ARL facilities and in a tandem configuration for the Cordin system described 

above; it is also used at some ARL experimental facilities as a permanent, buried, 

conductor. B/W twisted pair, the least expensive and least rugged, is used almost 

exclusively as the firing line of choice at TEF. The other 2 types of wires are 

intermediate in terms of expense and ruggedness. 
4 

Table 1 Physical properties and resistance of firing lines of interest 

Type Diameter 

(inches) AWG 

Resistance per 

1,000 ft 

(ohms) 

RISI “C” coaxial cable 0.059 (center conductor) ~15 3.18 

RISI twin lead blasting wire 0.032 20 10.15 

RG-58 coaxial 0.032–0.037 (center conductor) ~20 11.9 

B/W twisted pair 0.051 16 4.8 

In-house discussions also revealed that the 5-s spontaneity requirement for these 

experiments was less stringent than in some past in-house experiments using RP80-class detonators. It was learned that, during such past experiments, 

simultaneity of less than 1 s was achieved for 2 to 3 detonators. At that time, it 

was also concluded that multiple parallel legs with one detonator per leg provided 

a smaller simultaneity interval than one leg with multiple detonators in series. 

Other unique conditions associated with those past experiments (such as firing 

line lengths) may have contributed to the optimum circuit configurations that 

were adopted at that time. 

3. Experimental Setup and Firing Matrix

To establish a level of reliability using the actual onsite materiel and conditions, a 

series of detonator-only experiments was conducted. Figure 2 shows a wooden 

fixture that was designed and constructed to hold multiple detonators in place. 

The fixture facilitated the connection of each detonator to the firing circuit, while 

providing a view for high-speed video coverage. The high-speed video would 

verify detonation and simultaneity for each shot. Figure 3 shows a view of the 

fixture with the camera bombproof in the background. 
5 

Fig. 2 Fixture used for detonator-only experiments 

Fig. 3 View of fixture with camera bombproof in background
6 

Table 2 shows the firing matrix that was executed for the detonator-only 

experiments. The original matrix was devised to incorporate increasing numbers 

of detonators and their simultaneity using small parameter changes. The eventual, 

final matrix was developed as the experiments progressed, based upon the 

observed results. The description of results to be presented subsequently describes 

pertinent outcomes of select shots. Five shots are marked as having failed 

(i.e., failed to satisfy the 5-s simultaneity and/or non-interference criteria), and 

were especially valuable for identifying limiting aspects of the evolving initiation 

circuit. 

Table 2 Experimental firing matrix 

Date Shot TEF 

No. 

Firing 

Systems

Wire 

Type 

Firing 

Lines per 

Firing 

System 

Dets per 

Firing 

Line 

Total 

Number 

of Dets 

Check if 

Failed 

11/8/2013 1 39046 1 RG58 1 1 1 ... 

11/8/2013 2 39047 1 RG58 1 2 2 ... 

11/8/2013 3 39048 1 RG58 3 1 3 ... 

11/8/2013 4 39050 1 RG58 3 3 9 

11/8/2013 5 39051 1 RG58 3 3 9 

11/19/2013 6 39053 1 B/W 3 3 9 ... 

11/19/2013 7 39054 1 B/W 3 3 9 ... 

11/19/2013 8 39055 1 B/W 3 6 18 ... 

11/19/2013 9 39056 1 B/W 3 6 18 ... 

11/20/2013 10 39057 2 B/W 3 1 6 

11/20/2013 11 39058 2 B/W 3 1 6 

11/20/2013 12 39059 2 B/W 1 1 2 ... 

11/21/2013 13 39060 2 B/W 3 1 6 ... 

11/21/2013 14 39061 2 B/W 3 3 18 ... 

12/19/2013 15 39184 2 B/W 3 6 36 

12/19/2013 16 39185 2 B/W 3 6 36 ... 

A Phantom 7.3 high-speed digital video camera was used to observe the 

detonation events. Table 3 shows the camera settings for each shot. The 5-s 

desired spontaneity interval represented a near-limit condition for this camera, 

and was achieved by reducing the field of view and image resolution. The 

resulting video images were adequate to determine the relative initiation times for 

each detonator, although the resolution was so low as to sometimes produce 

blurred or grainy images. The high-speed video camera was used, to an extent, as 

a sensor rather than a pure image recorder. Examples of video frames obtained for 

several shots are included with the subsequent discussion of results herein. 
7 

Table 3 High-speed camera settings at 1-s exposure time 

Shot TEF No. 

Total 

Number of 

Dets 

Resolution 

(horizontal × 

vertical pixels) 

Frame 

Interval 

(s) 

Frame Rate 

(frames per 

second) 

1 39046 1 

2 39047 2 32 × 24 5 200,000 

3 39048 3 

4 39050 9 

5 39051 9 

160 × 64 

9 111,111 

6 39053 9 

6.25 160,000 

7 39054 9 

8 39055 18 

9 39056 18 

10 39057 6 

11 39058 6 

12 39059 2 

13 39060 6 

14 39061 18 

15 39184 36 

16 39185 36 

4. Experimental Results for a Single Firing System

Figure 4 shows 3 successive video frames capturing the initiation of shot 1, i.e., a 

single FS-43 firing system and one RP-80 detonator using RG58 wire. The 

camera interval was set to 5 s and is adequate to show an intermediate stage of 

growth in the light produced by the detonator initiation. 

Fig. 4 Successive video frames for shot 1 at 0, 5, and 10 s (left to right) 

Figure 5 is a diagram of the transfer box configuration used for shot 2, i.e., for one 

FS-43 firing system and 2 RP-80 detonators in series on a single leg of RG58 

wire. The length of firing line between adjacent detonators in series was several 

inches. This length was consistent with the length eventually used to connect, in 
8 

series, 1-inch-thick, 2-inch-diameter Comp B modular charges in contact with 

each other. Figure 6 shows 3 successive 5-s video frames capturing the initiation 

of shot 2, confirming that both detonators initiated within a 5-s interval. 

Fig. 5 Transfer box configuration for shot 2 

Fig. 6 Successive video frames for shot 2 at 0, 5, and 10 s (left to right) 

Figure 7 is a diagram of the transfer box configuration used for shot 3, i.e., using 

one FS-43 firing system and 3 RP-80 detonators, each connected to a parallel leg 

of RG58 wire. Figure 8 shows 3 successive 5-s video frames demonstrating that 

all 3 detonators initiated within a 5-s interval. 
9 

Fig. 7 Transfer box configuration for shot 3 

Fig. 8 Successive video frames for shot 3 at 0, 5, and 10 s (left to right) 

Figure 9 is a diagram of the transfer box configuration used for shots 4–7, i.e., for 

one FS-43 firing system and 9 RP-80 detonators total, with 3 detonators in series 

on each of 3 parallel legs. 
10 

Fig. 9 Transfer box configuration for shots 4–7 

Shots 4 and 5 both failed to function as desired. The detonators for shot 4 were 

arranged in a 3-× 4-inch area to retain the same camera field of view as previous 

shots. With the detonators in such close proximity, the same high-speed camera 

settings as the previous shot proved inadequate to visually determine if all 

detonators initiated within a 5-s interval. However, postshot inspection of the 

test site indicated that the detonators on 1 of the 3 parallel legs had been thrown 

from the immediate area. This suggested that predetonation interference had 

occurred. 

Shot 5 used the same circuit configuration as shot 4, but with 2 minor setup 

alterations. First, the detonators were separated from each other by several inches 

to eliminate the suspected predetonation interference. Second, the camera view 

was enlarged and resolution increased. Figure 10 shows 3 successive video frames 

(0, 9, and 18 s) for shot 5. While the 9-s frame interval was too large to 

conclusively determine if the 5-s simultaneity requirement was strictly satisfied, 

the second and third frames showed disparities in detonation initiation and 

progression that indicated questionable simultaneity. 
11 

Fig. 10 Successive video frames for shot 5 at 0, 9, and 18 s (top to bottom) 

Shot 6 addressed the initiation disparities observed in shots 4 and 5 by replacing 

the RG58 cable with the B/W twisted pair wire. Two negative aspects of the 

RG58 cable were cited: 1) that the larger resistance of the RG58 cable could 

produce a voltage drop too large for the circuit configuration, and 2) that 

differences between the geometries and properties of the inner and outer 

conductors of the RG58 cable could produce voltage anomalies. Prior to shot 6, 

the camera interval was reduced to 7 s. Figure 11 shows 4 successive video 

frames (0, 6.25, 12.5, and 18.75 s) for shot 6 demonstrating that all 9 detonators 

initiated within a 6.25-s interval and had similar progression. While the 6.25-s 

video frame interval was, strictly speaking, larger than the 5-s interval 

simultaneity requirement, the observed simultaneity and progression provided by 

the video was consistent enough to conclude that the 5-s simultaneity 

requirement was satisfied. 
12 

Fig. 11 Successive video frames shot 6 at 0, 6.25, 12.5, and 18.75 s (top to bottom) 

This sequence of video frames for shot 6 also demonstrates that the maximum 

visible light occurred in the third frame. With the particular camera settings for 

shot 6, the maximum visible light produced by the detonators occurred at 12.5 

 6.25 s. This aspect of the progression of visible light was consistent 

throughout the set of experiments. 

Shot 7 was a virtual repeat of shot 6 in terms of setup and performance, and the 

B/W twisted pair wire was adopted as the firing line of choice throughout the 

remainder of the detonator-only experiments as well as the modular charge shot. 
13 

Figure 12 is a diagram of the transfer box configuration used for shots 8 and 9, 

i.e., for one FS-43 firing system and 18 RP-80 detonators total, with 6 detonators 

in series on each of 3 parallel legs. Figure 13 shows 4 successive video frames (0, 

6.25, 12.5, and 18.75 s) for shot 8 demonstrating that all 18 detonators initiated 

within a 6.25-s interval and had similar progression. Shot 9 was a virtual repeat 

of shot 8 in terms of setup and performance. 

Fig. 12 Transfer box configuration for shots 8 and 9 
14 

Fig. 13 Successive video frames for shot 8 at 0, 6.25, 12.5, and 18.75 s (top to bottom) 

5. Experimental Results for 2 Separate Firing Systems

Shot 10 and all subsequent shots used 2 separate FS-43 firing systems in the 

initiation circuit. Shot 10 had 6 detonators total, with each of the 2 FS-43 firing 

systems having 3 detonators, and with each detonator connected to a parallel leg 

of B/W twisted pair wire. For shot 10, a Special Systems Inc 5-stage programmer 

was used to send an initiating pulse to both FS-43 control units. The camera 

position and settings were unchanged from the previous shot. The 4 successive 
15 

video frames (0, 6.25, 12.5, and 18.75 s) for shot 10 (Fig. 14) indicate that all 6 

detonators initiated but that the 2 subcircuits (each associated with each of the 2 

FS-43 firing systems) were out of synchronization by several microseconds. Shot 

11 was a virtual repeat of shot 10 and verified the synchronization disparity 

between the 2 subcircuits. 

Fig. 14 Successive video frames for shot 10 at 0, 6, 12, and 18 s (top to bottom) 

For the previous shots, the 5-stage programmer had been set up with open 

contacts that would close upon receiving the command input. Each of the FS-43 

control units had been connected to separate contacts within the 5-stage 

programmer. It was suspected that the 2 contact closures in the 5-stage 

programmer (one for each of the 2 subcircuits) did not close within the 5-s 

simultaneity requirement. 
16 

To achieve improved simultaneity between the 2 subcircuits, a modification to the 

initiation circuit for subsequent shots was adopted as follows. The 5-stage 

programmer output was moved to the closed contact connector, which operates by 

opening the contact upon receiving the command input. This connector was 

connected to a 50-VDC break box, which upon receiving the open circuit would 

output a single pulse. The single pulse was subsequently split and sent to each of 

the 2 FS-43 control units. 

This modified initiation circuit was evaluated in shot 12 by connecting only one 

firing line with one detonator to each FS-43 firing system. Figure 15 shows 4 

successive video frames (0, 6.25, 12.5, and 18.75 s) for shot 12 demonstrating 

that both detonators initiated within a 6.25-s interval and had similar 

progression. All subsequent shots used this modified initiation circuit. 

Fig. 15 Successive video frames for shot 12 at 0, 6.25, 12.5, and 18.75 s (top to bottom) 
17 

Shot 13 used the break box and 6 detonators total, with each of the 2 FS-43 firing 

systems having 3 detonators, and with each detonator connected to a parallel leg 

of B/W twisted pair wire. The circuit was the same as shots 10 and 11 but with the 

break box added. The 4 successive video frames (0, 6.25, 12.5, and 18.75 s) for 

shot 13 in Fig. 16 indicate that all 6 detonators initiated within a 6.25-s interval 

and had similar progression. 

Fig. 16 Successive video frames for shot 13 at 0, 6.25, 12.5, and 18.75 s (top to bottom) 
18 

Shot 14 used the break box and 18 detonators total, with each of the 2 FS-43 

firing systems having 3 parallel legs of B/W twisted pair wire, and with each leg 

having 3 detonators. Each of the 2 subcircuits was the same as shots 6 and 7. The 

4 successive video frames (0, 6.25, 12.5, and 18.75 s) for shot 14 in Fig. 17 

indicate that all 18 detonators initiated within a 6.25-s interval and had similar 

progression. 

Fig. 17 Successive video frames for shot 14 at 0, 6.25, 12.5, and 18.75 s (top to bottom) 
19 

Shot 15 used the break box and 36 detonators total, with each of the 2 FS-43 

firing systems having 3 parallel legs of B/W twisted pair wire and with each leg 

having 6 detonators. After the shot, it was realized that the break box had not been 

turned on. Figure 18 shows 4 successive video frames (0, 6.25, 12.5, and 

18.75 s) for shot 15. The top 18 detonators, which were connected to one FS-43 

firing system, initiated several microseconds before the bottom 18 detonators, 

which were connected to the other FS-43 firing system. 

Fig. 18 Successive video frames for shot 15 at 0, 6.25, 12.5, and 18.75 s (top to bottom) 
20 

Shot 16 was repeat of shot 15 except that the break box was turned on. The 4 

successive video frames (0, 6.25, 12.5, and 18.75 s) for shot 16 in Fig. 19 

indicate that all 36 detonators initiated within a 6.25-s interval and had similar 

progression. 

Fig. 19 Successive video frames for shot 16 at 0, 6.25, 12.5, and 18.75 s (top to bottom) 
21 

The 16 shots consisting of up to 36 detonators provided the verification of 

reliability and simultaneity needed to proceed with the 33 Comp B modular 

charge shot. Several other Comp B modular charge shots, using up to 7 charges 

connected in series on a single leg, were also conducted early in the program. 

Those shots demonstrated, among other things, that the Comp B modular charges 

could be initiated using RP-80 detonators without a booster pellet. 

Figures 20 and 21 show 2 views of the 33 Comp B modular charge setup. The 

postshot results indicated that a successful simultaneous detonation of 33 Comp B 

modular charges in close proximity was achieved. 

Fig. 20 Side view of 33 Comp B modular charge setup. (Photograph courtesy of Dr Muge 

Fermen-Coker.) 
22 

Fig. 21 Top view of 33 Comp B modular charge setup. (Photograph courtesy of Dr Muge 

Fermen-Coker.) 

6. Conclusions

The detonator-only experiments, along with the associated investigation into the 

required parameters, demonstrated an in-house capability for initiating 36 

detonators within a 5-s simultaneity interval. Relevant details concerning the 

setup of the initiation circuit were encountered during the process and contributed 

to the knowledge base. Those details included not only those aspects that 

contributed to successful application of the technology, but also those aspects that 

demonstrated inherent limitations. Perhaps most importantly, the experiments 

served to reaffirm the importance of establishing baseline characteristics on 

explosive operations such as simultaneous detonations, serving as a model for 

future experiments to be conducted safely and on a repetitive basis. 
23 

7. References

1. ARL Standard Operating Procedure 385-008. Static detonation of high 

explosives (outdoor facilities). Aberdeen Proving Ground (MD): Army 

Research Laboratory (US), 2009 Mar 3. 
24 

INTENTIONALLY LEFT BLANK. 
25 

Appendix A. Manufacturer‐Supplied Information Sheet on the

FS‐43

 

This appendix appears in its original form, without editorial change. 
26 
27 
28 

INTENTIONALLY LEFT BLANK. 
29 

Appendix B. Manufacturer‐Supplied Information Sheet on the

RP‐80

 

This appendix appears in its original form, without editorial change. 
30 
31 

Appendix C. Manufacturer‐Supplied Chart and Discussion Points

regarding Series‐Parallel Firing of EBW Detonators

 

This appendix appears in its original form, without editorial change. 
32 
33 

List of Symbols, Abbreviations, and Acronyms

ARL US Army Research Laboratory 

AWG American gauge wire 

B/W black and white 

EBW exploding bridge wire 

SOP Standard Operating Procedure 

TEF Transonic Experimental Facility 
34 

 1 DEFENSE TECHNICAL 

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