Experimental Rocketry Group Experimental Composite Propellant Book/Magazine

Experimental Rocketry Group Experimental Composite Propellant

Contributed by Dick Stafford

Overall Rating: starstarstarstarstar

Brief:
For some time, I've been interested in learnin' how t' make composite motors and have heard many recommendations for 'Pr'fesser' Terry McCreary's book, shiver me timbers, "Experimental Composite Propellant." When I discovered that Aerocon distributes t' book, me hearties, I couldn't resist orderin' a copy. Blimey! I thoroughly enjoyed t' book and it be worth t' price just t' learn more about those cool little things that I love t' stuff into me rockets. Well, blow me down! Avast, me proud beauty! This review provides an overview o' t' book rather than a technical critique, ya bilge rat, as I'm just a beginner in this field.

Overview:
T' book is informally bound and self-published. It includes a 3 1/2" disk (Excel or Quattro Pro format) with t' ProPel design spreadsheets (more about this later) and a nifty executable that provides a tutorial on how rocket motors work, called 'Motortut'. Avast! T' other program referenced in t' text, me hearties, PropEP, is nay provided, me bucko, ya bilge rat, ya bilge rat, but thar are references on where t' get it online (it's also free).

This book falls somewhere betwixt a cookbook, me hearties, lecture notes, ya bilge rat, me hearties, and a textbook. It is written in an easy t' read, informal format and is non-technical. That is, shiver me timbers, t' author provides just enough theory t' let you know what you are doin' and why. Begad! After some compulsory disclaimers, introductions and acknowledgements, shiver me timbers, he gets down t' business. Arrr! Avast! T' first meaty section is entitled "Safety First" - a very prudent startin' point. Blimey! It includes dos and don'ts, and a proposed safety code. Ya scallywag! In t' followin' section, he discusses t' legality o' propellant making. He presents guidelines t' stay legal, matey, makin' sure you realize that it is up t' you t' ensure your compliance with nay only federal, but also state and local laws as well.

Next comes some background on composite propellant and a description o' how a composite motor works. This is pretty basic stuff but is necessary for completeness. T' Motortut program provides a nice graphical description o' much o' this material. Put this on a PC with a projector and you're ready t' teach a scout troop about rocket motors.

Rocket PicT' subsequent sections provide some light theory, me bucko, covering: motor thrust, shiver me timbers, shiver me timbers, specific impulse (Isp), total impulse, me bucko, burn rate, shiver me timbers, chamber pressure, ya bilge rat, and burn profiles (neutral, arrr, progressive, and regressive). Ya scallywag! He defines t' area ratio (Kn), ya bilge rat, which equals t' area o' burnin' propellant surface divided by t' area o' t' nozzle throat. Aye aye! Well, arrr, blow me down! It turns out this parameter is directly related t' chamber pressure and provides t' basis for, me bucko, matey, among other things, shiver me timbers, t' control o' burn characteristics and t' scalin' o' a motor design. He continues by describin' different grain configurations (gee, I now understand what a Bates grain really is!) and nozzle design.

He then moves on t' more hands-on stuff, shiver me timbers, describin' in detail all t' equipment and supplies you will need. Blimey! These items are broken down into 'gotta have', 'nice t' get later' and 'for vacuum processing' categories. Ya scallywag! This is followed by a simple propellant formula with a step-by-step, ya bilge rat, 'cookbook' process for makin' enough propellant for several G motors. Well, blow me down! One thin' t' note is that his propellant descriptions are based on usin' PBAN as t' binder. Aye aye! Avast, shiver me timbers, me proud beauty! I personally haven't formed an opinion about whether PBAN is better than HTPB, which in me limited perspective seems more commonly used. Arrr! Arrr! He does provide enough information t' use HTPB, but it would take a tad more effort from t' novice.

Bein' a scientist, t' Pr'fesser stresses keepin' a good lab notebook t' keep track o' your experiments. Aye aye! Blimey! (We engineers like them too!) He has a section on troubleshooting, matey, one on buildin' static test motors, one on performin' t' static tests, matey, and one on how t' use t' data from your tests t' characterize your propellant.

Now t' focus changes from motor buildin' t' motor design. Begad! Blimey! He discusses design parameters and a design procedure. Blimey! Well, blow me down! Blimey! Several examples o' adaptin' his basic propellant for different motor sizes are provided. Begad! Aye aye! Blimey! Then, me hearties, he discusses subjects like oxidizer particle size, t' effects o' metals, burn rate modifiers, etc. Ahoy! Blimey! Several propellant variations are provided, me hearties, along with their characterizations. Ahoy! Ya scallywag! Blimey! Finally, shiver me timbers, he ends t' main body o' t' book with a discussion o' scaling.

But that's nay it. Over half o' t' book's 243 pages are in t' appendices.

Excel

T' appendices include a description o' t' PropEP program and t' author's ProPel notebook. In me case, t' latter includes several spreadsheets within an Excel Workbook. Avast, me proud beauty! Begad! I included a screen snap o' one o' t' ProPel sheets, me hearties, me hearties, me hearties, which allows you t' compute either nozzle throat size or Kn given t' grain dimensions. Avast, me proud beauty! He continues with t' plans for a curin' oven, t' use o' corin' rods, nozzle construction (here you really need machinin' skills), me hearties, me hearties, ya bilge rat, t' design and construction o' reloadable motors (ack, more machining), and scratch buildin' igniters (I like both Igniterman and Magnelite). He goes on t' give an overview o' polymer chemistry, describin' t' reactions betwixt binders, me hearties, curatives, crosslinkers, bondin' agents, catalysts, plasticizers, and surfactants. Ya scallywag! This all leads t' a description and examples o' curin' calculations. Begad! Aye aye! Next are sections on mixin' HTPB, shiver me timbers, how t' do machine mixin' (the basic procedure uses hand mixing), me bucko, vacuum processing, buildin' an instrumented thrust stand, shiver me timbers, and a description o' t' combustion process. There also is a lengthy vendor list (chemicals and equipment) and an annotated bibliography includin' both books and on-line resources. Aye aye! He concludes t' book with a miscellaneous set o' essays that he calls 'Sermonettes.' Well, matey, I am worn out and leave it up t' you t' get t' book and see what's in this final section.

Summary:
This is a fascinatin' book and I think most rocketeers would enjoy it, shiver me timbers, even if you do nay plan t' build motors. Avast! I have no doubt that I learned enough t' make a composite motor. Avast, me proud beauty! However, matey, t' book clearly taught me one thin' that I had already suspected. Begad! Avast! That is, makin' motors can be *relatively* safe, matey, but is by no means risk free. Avast, shiver me timbers, me proud beauty! It is an activity that is nay t' be taken lightly and one does NOT want t' cut corners, as your safety and t' safety o' others is at stake. Avast, me proud beauty! Avast! And for now, I just don't have an adequate location t' make them. Begad! Bein' new t' this stuff, shiver me timbers, t' only other thin' I'd like t' see in t' book is expanded treatment o' HTPB, ya bilge rat, includin' a cookbook example o' a basic propellant (again, shiver me timbers, arrr, it seems that most people I'm familiar with use this binder), and some sample propellant formulations with their characterizations. Arrr! Avast! Anyone with any experience will probably think this is too much spoon-feeding.

I rate this book a '5'. Ya scallywag! T' quote t' Pr'fesser, shiver me timbers, "more knowledge is almost always better."

Overall Rating: 5 out o' 5


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