Simultaneously Gained Streak and Framing Records Offer a Great
Advantage in the Field of Detonics

Manfred Held*

TDW – Gesellschaft fu¨r verteidigungstechnische Wirksysteme mbH, 86523 Schrobenhausen (Germany)

Summary

Many examples have demonstrated the particular advantage of

simultaneous and parallax-free recordings of events with frames and a
streak record in the field of shock waves and detonation physics.

1. Introduction

The danger of misinterpreting streak records in their own

was pointed out long time ago by Sultanoff

(1)

. He proposed

the simultaneous use of a streak camera with a single-frame
camera fitted with a Kerr cell shutter. The image was
projected without parallax via a beam splitting mechanism
onto a streak camera and a framing camera (Figure 1). How-
ever, a clear coordination of the observed section on the
streak record in the framing picture is not given. On the other
hand, the simultaneous streak and framing rotating mirror
cameras Cordin Model 200 and Cordin Model 330

(2)

demon-

strate an exact coordination of the streak record with the
gained framing pictures which were recorded simultaneously
with the same lens and therefore without parallax failure.
These simultaneous streak and framing rotating mirror
cameras are not essentially different from normal rotating
mirror streak and framing cameras. The only difference is
that they additionally have a special beam splitting system in
which the light for the streak record passes through a very
narrow slit in the mirror and is therefore blanked out from the
framing sequence. The rest of the picture is fully available for
the framing record (see Figure 2). This special blanking out
has the great advantage that no light is lost – neither for the
frames nor for the streak records – and that the streak slit is
marked as a reference line in the frames and therefore, the
streak record can be unmistakably coordinated to the frames.

2. Examples

Even such a simple thing as the measurement of the speed

of a shock wave, which is certainly the domain of streak

records, can be improved by the additional use of simulta-
neously gained frames. The frames in Figure 3

(3)

show that

the streak picture recorded the desired process and that no
phase velocities are present which would otherwise lead to
erroneous analyses.

To measure the detonation velocity, a cylindrical test

charge was fixed to a piece of wood (Figure 4). The air gap
between the high explosive charge and the wood surface,
increasing with the radius, caused a so-called precursor air
shock

(4)

. The frames show that this precursor air shock does

just not disturb the measurement of the detonation velocity in
the observation of the streak plane.

* e-mail: [e-mail]

Figure 2. Light beam passes of a simultaneously recording streak and
framing rotating mirror camera.

Figure 1. Simultaneous record of an event with two cameras, one in
streak and the other in a framing mode

(1)

.

#

WILEY-VCH Verlag GmbH, D-69469 Weinheim, 2001

0721-3115/01/0306 – 0148 $17.50

þ:50=0

148

Propellants, Explosives, Pyrotechnics 26, 148–155 (2001)

Figure 4. The frames show on the black line, where the streak is taken out, that the detonation velocity is not disturbed from the precursor air
shock in the air gap between the supporting wood and the cylindrical charge.

Figure 5. The frames demonstrate an eruptive or wavy detonation front for the underwater high explosive charge where the streak record gives
the accurate detonation velocity (HE

¼ APC=Al=RDX=PB 27=22=37=14).

Figure 3. Parallax-free simultaneously gained frames and streak record of a shock wave event

(3)

.

Propellants, Explosives, Pyrotechnics 26, 148–155 (2001)

Advantage in the Field of Detonics

149

Figure 7. Frames and streak record of a critical diameter test with TSST

(6)

.

Figure 6. Less sensitive high explosive charges have low intrinsic luminosity. Only the frames can be analyzed with background illumination on
detonation velocity and on the strength of the reaction with the radial expansion velocity

(5)

.

Figure 8. Frames and streak record of a radial or corner turning distance test

(7)

.

150

Manfred Held

Propellants, Explosives, Pyrotechnics 26, 148 – 155 (2001)

The detonation frames of an underwater charge, contain-

ing aluminium and plastic binder are shown in addition to the
streak record (Figure 5). Characteristic is the appearance of
the bright luminous band showing the booster detonation
followed by the narrow trace of the detonation of the
aluminized underwater high explosive charge in the streak
record, which has an eruptive propagation in the frames. This
pulsing detonation cannot be recognized in the streak record.

Less sensitive high explosives rarely show any intrinsic

luminosity under reduced detonation pressure. When obser-
ving the charges with background light, the detonation
velocity can be evaluated from the framing records and
additionally also the strength of the reaction

(5)

(Figure 6).

The frequently insufficient illumination of the detonation

of many of the modern less sensitive high explosives led to
the introduction of the so-called Tangent Streak Slit Tech-
nique (TSST)

(6)

. However, to evaluate these streak records,

it is also necessary to look at frames to eliminate any doubt
that these streak records have not been falsified by other
events, like precursor shocks. For comparison, the TSST is
also very suitable for the measurement of the critical
detonative diameter on high explosive charges. Following
the overinitiation, the dying reaction wave can be well
observed with the Tangent Streak Slit Technique (Figure 7).

In the radial or corner turning distance tests

(7)

the frames

at Figure 8 show as an example that after about 1 ms the
breakthrough of the detonation wave was not quite symme-
trical to the streak plane. This has to be taken into account for
defining the virtual initiation distance (VID)

(8,9)

. Using the

profile technique (Figure 9), it can be clearly shown, qualita-
tively from the frames and quantitatively from the streak
records, that in the radial tests with discs of limited height
only the central core detonates, whereas with greater heights
the edges of the charges are also detonating (Figure 10).

Without the help of frames it is easy to misinterpret the

streak records of cylinder tests (Figure 11). In the case of less
sensitive high explosive charges, eruptions often occur in the
2.5 mm thick copper cylinder (Figure 12).

The initiation in the hole of a tubular charge also creates

problems, especially when the wall thickness is relatively

thin. In the example (Figure 13) the wall thickness of 8.5 mm
is too thin and only a forward detonation and no reverse
detonation takes place. The fact that no reverse detonation
occurs can clearly be seen only from the frames. On the other
hand, with a wall thickness of 28 mm of the tubular charge, a
detonation occurs both, forwards and reverse

(10)

.

Initiation phenomena in the case of shaped charge jets can

also be observed and analysed especially well with the aid of
simultaneous streak and framing records. Surprisingly, such
tests show that the charge reacts less sensitively when it is
fixed directly to the back of a barrier than separated by an air
gap

(11)

. If an acceptor charge is divided and arranged in some

distance with an air gap, tests show that the section of the
charge in contact to the barrier is not directly initiated by the
jet, whereas the following section behind the air gap is
initiated. The first perforated section is then initiated by the
second detonating section in the reverse direction. From the
frames (Figure 14) it can be seen that the detonation in the
second section starts somewhat asymmetrically, thus indicat-
ing the closeness of the limit of initiation. From the streak

Figure 10. Frames and streak records of the axial breakthrough of the
reaction products in profile streak technique.

Figure 9. Test setup for observation of the axial breakthrough of the
reaction products in profile streak technique.

Figure 11. Test setup for measuring the radial expansion velocity in a
cylinder test.

Propellants, Explosives, Pyrotechnics 26, 148–155 (2001)

Advantage in the Field of Detonics

151

record, the delays in the first section and the corner turning
distance in the second can be evaluated very precisely

(12)

.

If the acceptor charge in the above arrangement is

shortened, the breakthrough of the detonation in the acceptor
charge can be additionally observed quite easily by a mirror.
Two different arrangements of charges to the barrier are

reported in the following initiation tests. In the first case
the test charge is placed in contact to a 50 mm thick steel
barrier, and in the second there is an air gap between the
charge and a 100 mm thick steel barrier (Figure 15)

(13)

. The

length of the acceptor charge was varied. As the frames of a
30 mm thick acceptor charge – especially observed over the

Figure 12. Frames and streak record of a cylinder test with a not very powerful high explosive charge.

Figure 13. Frames and streak records of radial initiation tests with different wall thickness of the high explosive tube.

Figure 14. Initiation of a splitted acceptor charge by a shaped charge jet

(11)

.

152

Manfred Held

Propellants, Explosives, Pyrotechnics 26, 148 – 155 (2001)

mirror – show, there is no detonation in the centre in this
arrangement (Figure 16). However, in the diagonal at the
edge of the charge there is a light detonation ring, clearly
recognizable in the streak record after about 4 ms. If the
acceptor charge is increased from 30 mm to 40 mm

(Figure 17), the complete detonation can be seen, both in
the frontal and in the radial breakthrough, however with
great corner turning distance (CTD). If the charge is tested in
the arrangement with an air gap of 15 mm, a 10 mm thick
acceptor charge causes no detonation. This can be clearly
seen in the frames and streak records (Figure 18). However,
if the acceptor charge is 20 mm thick, the frames and streak
records clearly show a detonation, altough the axial break-
through and the CTD can be evaluated in great detail from
the streak records (Figure 19). These jet initiation tests are a
particularly good example of the interplay of simultaneously
gained streak records and frames. The ‘‘streak slit’’ allows
the analysis whether the jet exits from the steel barrier in the
streak plane, and one can see that the true velocities are
measured and not the phase or the bow wave velocities. In
the upper part of the streak record the impact velocity and
the residual velocity of the jet, the corner turning distances
(CTDs)

(7)

and time delays can be quantitatively evaluated; in

the lower part (mirror image), the virtual initiation distance
VID from the axial breakthrough of the reaction or the
detonation wave can be evaluated

(8)

.

Figure 16. 30 mm thick acceptor charge (TNT=RDX 35=65) in contact to a barrier, attacked by a shaped charge jet after a perforation of 50 mm
mild steel.

Figure 17. The same arrangement as Figure 16 but with 40 mm thick acceptor charge.

Figure 15. Test setup of shaped charge initiations with shortened high
explosive charges in contact, respectively air gap to the barrier.

Propellants, Explosives, Pyrotechnics 26, 148–155 (2001)

Advantage in the Field of Detonics

153

3. Conclusion

The simultaneous recordings of events with frames and

streak records without parallax, using the same lens, display
the special advantage that the streak records can be clearly

related to the always spatial events. On the one hand the
frames give spatial information on the overall event, which is
always useful for a better understanding of the streak records
and is sometimes even necessary. However, the frames have
motion blur due to the limited exposure times in the very fast
detonative processes and contain time gaps during the
interval times (Figure 20). But from the frames one can
immediately see whether the streak record was made in the
symmetry plane or whether phase velocities were registered
in the streak records. Without any doubt, streak records
produce a continuous recording, a much better time and
space resolution, even if only in the observation plane.

The following table provides a quick overview of the

special advantage of frames and streak records and the
specific advantages of simultaneous recording.

There are available on the market as individual devices,

rotating mirror framing cameras with higher picture quality,
and rotating mirror streak cameras with higher time and
space resolution, which are better than the simultaneous
streak and framing rotating mirror cameras currently avail-
able. The author is however prepared to sacrifice the higher
quality of the framing and streak records for the advantages
of parallax-free, simultaneously gained frames and streak

Figure 19. 20 mm thick acceptor charge in the same arrangement as Figure 18.

Figure 18. 10 mm thick acceptor charge TNT=RDX 35=65 arranged at 5 mm air gap behind a 100 mm thick barrier.

Figure 20. Comparison of a continuous streak record with very high
time and space resolution in the observation direction with a series of
frame images with two-dimensional pictures of the event.

154

Manfred Held

Propellants, Explosives, Pyrotechnics 26, 148 – 155 (2001)

records, since this combined information is far more impor-
tant for the interpretation and evaluation of many detonic
events than the possibly better quality achieved with other
equipments used alone.

4. References

(1) M. Sultanoff, ‘‘Some Philosophical Aspects of High-Speed

Photography Instrumentation’’, 5th Int. Congress on High Speed
Photography, 411 – 416 (1960).

(2) CORDIN, 2230 South 3270 West, Salt Lake City, Utah 84119,

USA.

(3) M. Held, ‘‘Measurement of the Shock Profiles, with Streak

Technique and Different Detonating Arrangements’’, San Diego,
Proceedings of the Society of Photo-Optical Instrumentation
Engineers SPIE, Vol. 1346, pp. 311 – 318, (1990).

(4) M. Held, ‘‘Influence of Longitudinal Gaps on the Detonation

Front’’, Propellants, Explosives, Pyrotechnics 20, 170 – 177
(1995).

(5) M. Held, ‘‘Diagnostic of the Reaction Behaviour of Insensitive

High Explosives under Jet Attack’’, 19th Congress on High Speed
Photography and Photonics, Cambridge UK, SPIE, Vol. 1358,
pp. 1028 – 2021, (1990).

(6) M. Held, ‘‘Tangent-Streak-Slit-Technique’’, 18th Int. Congress

on High Speed Photography and Photonics, Xian, China, SPIE
Vol. 1032, pp. 850 – 854, (1988).

(7) M. Held, ‘‘Corner-Turning Distance and Retonation Radius’’,

Propellants, Explosives, Pyrotechnics 14, 153 – 161 (1989).

(8) M. Held, ‘‘Initiierungsabstand und Detonationsradius’’, 22nd Int.

Annual Conference of ICT, Karlsruhe, Germany, July 2 – July 5,
1991, pp. 3.1 – 15.

(9) M. Held, ‘‘Influence of the Initiation Intensity on the Radial

Detonation

Breakthrough’’,

Propellants,

Explosives,

Pyro-

technics 20, 245 – 251 (1995).

(10) M. Held, ‘‘Retarded Detonation’’, 6th Symposium on Detonation,

1976, pp. 225 – 230.

(11) M. C. Chick and D. J. Hatt, ‘‘The Mechanism of Initiation of

Composition B by a Metal Jet’’, 7th Symposium on Detonation,
1981, pp. 352 – 361.

(12) M. Held, ‘‘Experiments of Initiation of Covered, but Unconfined

High Explosive Charges by Means of Shaped Charge Jets’’,
Propellants, Explosives, Pyrotechnics 12, 35 – 40, 97 – 100,
167 – 174 (1987).

(13) M. Held, ‘‘Analysis of the Shaped Charge Jet Induced Reaction

of High Explosives’’, Propellants, Explosives, Pyrotechnics 14,
245 – 249 (1989).

(Received December 28, 1997; Ms 1997=060)

Table 1.

Topic

Frames

Streak records

Spatial picture

þ

7

Space resolution

7

þ (but only in 1 plane)

Time resolution

7

þ

Full-time observation

7

þ

Interpretation

!

No phase velocities

!

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