Manufacture of ALCLO Pellets, Granules and Powders 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.

Nowadays, there is a considerable amount of technical information available to aid the rocket builder in their 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 anyone 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 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 to the average rocketeer, 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 of the manufacture of ALCLO.

Presently , there are no companies in the U.S. that manufacture ALCLO for re-sale. However, it is still manufactured by various contractors as a load material for use in specific pyrotechnic devices (usually igniters) , which they or other sub-contractors assemble. In other words, it is not an “off-the-shelf “ item, as is the case with Boron / Potassium Nitrate ( BKNO3 ) ignition pellets, and granules.

Of the companies that do manufacture this material for in-house use, or as a load material in a finished product (that they then supply to another customer); each one has its own proprietary process for converting the constituent ingredients into a finished ignition material. The author has experienced in his professional capacity, that these few companies that still do manufacture and use ALCLO, are very hesitant when it comes to discussing any of the technical details concerning its manufacture. Likewise, the operation of the various types of processing equipment used to make ALCLO is somewhat of a very closely held secret.

While many of the solid propellant rocket motors available to today’s rocket enthusiasts ( whether they be modelers, “build it yourself” experimentalists ) who build and fly rockets that utilize modern, near state of the art, composite solid propellants; 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 ALCLO previously here-to-fore undisclosed to a majority of those in the traditional non-professional experimental, and high power rocket communities. It is quite possible that many readers have never even heard of ALCLO. The other portion of the ignition methodology issue; the design of the igniter itself , will be discussed in greater detail in yet another publication specifically devoted to that topic.

While a complete and thorough understanding of this topic 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, and focus primarily on the manufacturing and processing aspects of this material.