Experimental and High-Power Rocketry

1. Experimental and High-PowerRocketry FROM BOB BRASHEAR MADE BY TONY BRASHEAR

2. Introduction • Some History • Some Definitions • Some Technical Stuff • A Whole Freakin’ Bunch of Regulations • Organizations

3. SOME HISTORY • 1950’s: Explosion of model rocketry. First commercial production of compressed black powder motors for model rockets. Model rocket motor impulse classes A through B. Implementation of campaign to kill off experimental/amateur rocketry for “safety” reasons.

4. MORE HISTORY • 1960’s: Virtual monopoly of commercial model rocket motors. Experimenters driven underground and classified as “basement bombers”. Model rocketry, as we know it today, matures. Some work on composite motors for hobby rocketry begins.

5. EVEN MORE HISTORY • 1970’s: High Powered rocketry enters the picture. EX is still underground. Renegades are conducting launches outside of NAR control. Black powder motor impulse classes reach F.

6. JUST A BIT MORE HISTORY • 1980’s: Concerted effort by NAR to kill High Power. Tripoli Rocketry Association is born and holds first national launch called LDRS (LARGE and DANGEROUS ROCKET SHIPS). NAR/Tripoli battle ensues.

7. SORRY, A BIT MORE HISTORY • 1990’s: Great Truce. NAR and TRA kiss and make up (sort of). NAR and TRA recognize each others motor certification lists. NAR moves into High Power Rocketry. TRA does “experimental rocketry”.

8. I PROMISE, THE LAST ONE • 2000’s: TRA/NAR lawsuit against BATFE. EX comes out of the closet. Battle now between EX and hobby rocketry community.

9. SOME DEFINITIONS • Motor Impulse Classes (Total Impulse) A 1.25 2.5 B 2.51 5 C 5.01 10 D 10.01 20 E 20.01 40 F 40.01 80

10. A FEW MORE DEFINITIONS • Motor Impulse Classes (continued) G 80.01 160 H 160.01 320 I 320.01 640 J 640.01 1280 K 1280.01 2560 L 2560.01 5120

11. AND SOME MORE … • Motor Impulse Classes (continued) M 5120.01 10240 N 10240.01 20480 O 20480.01 40960 P 40960.01 81920 Q 81920.01 163840 R 163840.01 327680

12. TECHNICAL STUFF BP PART 1 • BLACK POWDER (BP) MOTORS* • Black Powder Motor Components • Black powder motors consist of four primary components, all of them non reusable. The case is, almost always, wound paper. Paper has good coefficent of expansion at standard storage temperatures when loaded with black powder, an item important when you don't want your grain to seperate from the liner. It also ablates well with the bare flame present in the end burn BP motor. Clay is used for the nozzle, due to its low cost and its low ablative properties with BP's consistent pressure and burning properties. A delay/smoke column similar to composite motor delays is placed at the top of the grain. The final item is the loose black powder ejection charge, which is sealed with either a thin layer of clay or a paper cap.

13. TECHNICAL STUFF BP PART 2 • Black Powder Motor Manufacture • Black powder motors are manufactured with specialized hydraulic pressing machines which have precise controls to press black powder into the casings. Black Powder has a fine line between compression and self ignition, pressures up to 900 to 1000 psi. are typical pressures for pressing but a slight increase in this pressure can lead to combustion. The rear section of the motor then gets a clay nozzle, the forward end of the motor gets the delay and smoke generator charge followed by the ejection charge and charge cap.

14. TECHNICAL STUFF BP PART 3 • Thrust Classes • Black Powder cannot be easily modulated or enhanced by additives as easily as composite propellants, other than "effects" additives such as titanium or other metals for spark effects. This means the only way to produce different thrust motors is to change the diameter of the grain face (average thrust) or lengthen the grain (total thrust).

15. TECHNICAL STUFF COMPOSITES PART 1 • Composite vs. Black Powder • Composite motors are the motors we think of when we think "High Power Rocketry". Black Powder (BP) motors become, more and more, temperature sensitive, the longer and wider the fuel slug is, hence cracks can appear in the slug. As black powder has no burn modulation techniques, it inherently burns/ignites more rapidly than composites. A larger surface area from a crack can over-pressurize a nozzle in microseconds. The specific impulses of black powder are very low compared to composite propellants so more and more energy is wasted in lifting itself, pound for pound, relative to composite propellant motors. Composite motors are safer, requiring a high, consistent heat source to ignite, whereas BP can be lit with a spark

16. TECHNICAL STUFF COMPOSITES PART 2-1 • Composite Ingredients • Composite Propellant is made of, primarily, two major materials, mixed wet, and then cured into a solid, albeit, rubbery form via an "epoxy style" process. Other items are used for effects and mass flow regulation. The major composite motor components are: • 1. Oxidizer. Commercially, Ammonium Perchlorate (AP) in granular form between 90 to normally 200 micron size is used, although some experimentalists use other oxidizer materials such as Ammonium Nitrate (AN). AN propellants traditionally have a lower specific impulse (energy per pound) but this, of course relies on finer tuning of the other components.

17. TECHNICAL STUFF COMPOSITES PART 2-2 • 2. Fuel-Binder. This can be one material or two but both aspects are important. The fuel , of course does the work, and the binder is the item that makes the mass a solid. • 3. Effects. Various metals are usually added to allow a multitude of flame and burning characteristics. Normally, composite motors burn without smoke, but additives are normally added to enhance tracking or even to modify the burn to a slower impulse for some vehicles. • 4. Miscellaneous. Items such as a blackening agent to darken the propellant to inhibit IR transmission and other ingredients to deaden noise and other characteristics of a solid fuel burn are also important.

18. TECHNICAL STUFF COMPOSITES PART 3-1 • Composite Motor Types • There are two primary types of approved composite rocket motors, the single use and the reloadable. They are as follows: • Single Use This motor is assembled at the manufacturer in either a plastic, fiberglass or aluminum tube (called a case). Propellant is either poured or inserted into the case and then the ends are permanently attached These ends consist of a nozzle on the aft end and forward plug that may include either a delay stack with an ejection well or just a closed plug. This motor is always thrown away after use.

19. TECHNICAL STUFF COMPOSITES PART 3-2 • Reloadable motor These types of motors come in two closure systems, threaded and bushing/snap-ring closures. The Aerotech Reloadable Motor System (RMS™) is an example of a threaded system.. The bushing/snap ring system pioneered by Dr. Frank Kosdon, among others, is a system where the forward bushing plug and the aft nozzle bushing are retained through snap rings inserted into internal grooves in the case at the proper length case for that motor. These bushing plugs can slide, within the case, but at pressurization, are forced to, and retained by, the snap rings. The essential propellant components, the grains, are loaded the same, however. Different length cases are provided, for all reloadable motors, in standard diameters, normally measured in millimeters, and various lengths, measured either by length or, even more common, by maximum thrust (Newton Seconds) per case.

20. TECHNICAL STUFF HYBRIDS • Hybrid Motors • Hybrid motors are specifically rocket motors that use a fuel and an oxidizer that are in two different states, in this case, a solid fuel (plastic, cellulose, paper, etc) and a liquid/gaseous oxidizer (primarily nitrous oxide). Nitrous Oxide has the stable characteristic of becoming a good to better oxidizer, the hotter it gets. This fact allows it to be handled safely at room temperature, and provide a controlled burning with an ignition source, continuous flame. This, minus some ignition systems makes a motor system that is completely safe and "explosive free". The fuel used, usually plastic can provide the same specific impulse as Ammonium Perchlorate Composite Propellant (APCP) motors at, in most cases, one third to one half the cost.

21. THOSE STINKIN’ REGULATIONS • Who do we deal with? FAA BATFE STATE LOCAL

22. ORGANIZATIONS (FINALLY!) • National Association of Rocketry • Tripoli Rocketry Association • International Experimental Aerospace Society