Manufacture of BKNO3 Ignition Granules and Pellets by Chuck Piper

Obtaining a reliable, safe, and inexpensive means of igniting solid propellant rocket motors has long been a goal of both the professional, and hobbyist rocket builder.

Today, there exists a considerable body of technical information to aid the rocket builder in the design and construction of solid propellant rocket motors, and flight vehicles. Unfortunately, very little technical information exists on igniters and igniter materials that is written at comprehension level that can be reasonably understood by any but the most technically astute of these individuals. In other words, you really do have to be “a rocket scientist” to understand most of it!

That which does presently exist, is usually embodied in highly technical reports, journals, and manuals, whose distribution is essentially limited, to those persons in the defense or aerospace industry, on a need to know basis. That information which is available, and is not considered as “defense sensitive”, is in many instances, closely held as “company proprietary information” by those who have developed it. This is particularly true in the case of the manufacture of BKNO3 ignition granules and pellets.

Of the two or three companies that still manufacture this material for re-sale in the U.S.; each one has its own special procedures for manipulating the constituent ingredients into a finished product. The author has found in his professional capacity, that while manufacturers of BKNO3 are quite willing to discuss such details as the chemistry of BKNO3 (they’ll come right out and give you the exact percentages of the ingredients used), they are deliberately evasive, when it comes to discussing any of the details concerning the various types of processes, or equipment used in its manufacture. Trying to obtain any truly relevant information on this topic is like “pulling teeth”. As we all know, “the Devil is in the details”.

While many of the solid propellant rocket motors available to today’s rocket enthusiasts who build and fly rockets that utilize modern, near state of the art, composite solid propellants (whether they be modelers, “build it yourself” experimentalists , or the more recent category of aficionados known as high-power rocketeers); the means of reliably igniting these motors (i.e. igniter technology, and igniter materials) has clearly lagged far behind that of motor development.

The purpose of this report then, is to partially bridge this “informational gap” between motor technology and ignition methodology, by addressing much of the information concerning BKNO3 previously here-to-fore undisclosed to a majority of those in the traditional non-professional experimental, and high power rocket communities. The other portion of the ignition methodology issue; the design of the igniter itself, will be discussed in greater detail in another publication specifically devoted to that topic.

Although a complete and thorough understanding of this subject cannot be accomplished without an extensive discussion of chemistry, physics, thermodynamics, gas dynamics, and other advanced engineering disciplines , we have opted to take a somewhat less rigorous approach. Rather than burdening the reader with volumes of highly technical information, we have included a reference section at the end of the report for those wishing a more detailed discussion of the subject material presented. We hope that this report will assist you in your quest of producing ignition materials for use in igniters for those bigger, better, safer, and more reliable rockets.