A History of Research and a Review of Recent Developments

Equivalent pressure factors 55
Figure 2.21 Relationship between peak instantaneous underwater shock pressure
and the slant range for underwater nuclear explosions (from Glasstone and Dolan,
ref. 2.9).
review of surface and seabed interactions in a book by Smith and Hetherington
[2.38] of Cranfield University (Royal Military College of Science). Researchers
might also usefully consult the work of Henrych [2.39], mentioned in the
Introduction to this book.
2.5 EQUIVALENT PRESSURE FACTORS
We have already noted the custom of using TNT as the basis for information on
blast pressure. This information can be applied to other explosives by multiplying
the mass of the explosive by a conversion factor, as described in Tables 2.2 and 2.5.
Equivalent pressure factors for well-known modern explosives are 1.27
(PETN), 1.40 (Pentolite) and 1.07 (Tetryl). A recently developed explosive
that became famous as the result of terrorist activity is Semtex, manufactured
in what is now the Czech Republic. Some information on its behaviour is
given in a paper by Makovicka [2.40], which included a figure giving the
relationship between peak incident pressure and the weight of charge at a
point 7 metres distant from the centre of the explosion. This relationship can
be expressed approximately as follows:
Weight of charge (grams) 300 600 800 1000 1200
Peak incident pressure at 7 m (KPa) 15 22 25 27.5 28