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Increased impulse of solventless
extruded double base rocket propellant
by addition of high explosives RDX and FOX-7.
Erik Tunestål
EURENCO Bofors – 691 86 KARLSKOGA, Sweden
e.tunestal@eurenco.com – Phone: +46736683221
1- BACKGROUND
At Björkborn in Karlskoga propellants have been manufactured for more than a century.
Thanks to Alfred Nobel’s work in nitroglycerine it all started with double base formulations.
Over the years several compositions have been developed and we have now passed 1400
serial production recipes.
An area of propellant manufacturing is the extruded solventless double base rocket
propellants. These are smokeless propellant grains mainly used in short range systems like
shoulder-launched systems, unguided rockets and surface-to-air missiles and rockets. These
are propellants with ballistic modifiers which alter the burning characteristics of the propellant,
the goal is to have a low pressure exponent around the design pressure of a system. This
paper describes work done in the area of broadening the performance and possibilities of
using high explosives in rocket propellant formulations to increase the specific impulse.
2- OBJECTIVE
This project’s objective was to investigate if increasing the specific impulse in double base
propellants by adding high explosives affects other apparent parameters of the propellant.
The high explosives evaluated in the project is precipitated FOX-7 with an average crystal
size of around 12 microns and RDX with an average crystal size of around 6 microns.
The experimental plan consisted of six tests described in the table below.
The specific impulse is calculated from internal thermochemical codes. Since each gram of
FOX-7 and RDX contains the same molecules the theoretical specific impulse is the same.
3- PREPARATION OF HIGH EXPLOSIVES
This segment describes the manufacturing techniques which Eurenco Bofors has developed
for producing small size RDX and FOX-7 products.
3.1- RDX
The RDX crystals of propellant grade are produced in the standard RDX plant at Eurenco
Bofors. The process consists of first producing normal hexogen in the plant. This hexogen
Specific Impulse
(Ns/kg)
Expansion 70 to 1 bar
