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33-406: All versions of UA120 shared a common design, with the only significant differentiating factor being the length of the motor. It was a segmented design, with between five and seven motor segments possible. A solid propellant used was a ammonium perchlorate composite propellant with polybutadiene acrylonitrile (PBAN) binder. The stage had an external diameter of 120 inches. Attitude control in flight

66-495: A hydroxyl functional group . It reacts with isocyanates to form polyurethane polymers. HTPB is a translucent liquid with a color similar to wax paper and a viscosity similar to corn syrup. The properties vary because HTPB is a mixture rather than a pure compound , and it is manufactured to meet customers' specific requirements. A typical HTPB is R-45HTLO. This product consists of oligomeric units typically containing 40–50 butadiene molecules bonded together, with each end of

99-505: A strand burner test. This test allows the APCP manufacturer to characterize the burn rate as a function of pressure. Empirically, APCP adheres fairly well to the following power-function model: It is worth noting that typically for APCP, n is 0.3–0.5 indicating that APCP is sub-critically pressure sensitive. That is, if surface area were maintained constant during a burn the combustion reaction would not run away to (theoretically) infinite as

132-410: A rubbery binder as part of the fuel. The propellant is most often composed of ammonium perchlorate (AP), an elastomer binder such as hydroxyl-terminated polybutadiene (HTPB) or polybutadiene acrylic acid acrylonitrile prepolymer (PBAN), powdered metal (typically aluminium ), and various burn rate catalysts . In addition, curing additives induce elastomer binder cross-linking to solidify

165-946: A strap-on booster on Titan 34D and Commercial Titan III . UA1207 was first flown in 1989 and used on Titan IV-A . It was proposed for several other variants of Titan III and IV, as well as the Titan-IIIM , derivatives of the Saturn rocket family and the Space Shuttle . Ammonium perchlorate composite propellant Ammonium perchlorate composite propellant ( APCP ) is a solid rocket propellant . It differs from many traditional solid rocket propellants such as black powder or zinc-sulfur , not only in chemical composition and overall performance but also by being cast into shape, as opposed to powder pressing as with black powder. This provides manufacturing regularity and repeatability, which are necessary requirements for use in

198-733: A variety of different characteristic propellant types. These can range from fast-burning with little smoke and blue flame to classic white smoke and white flame. In addition, colored formulations are available to display reds, greens, blues, and even black smoke. In the medium- and high-power rocket applications, APCP has largely replaced black powder as a rocket propellant. Compacted black powder slugs become prone to fracture in larger applications, which can result in catastrophic failure in rocket vehicles. APCP's elastic material properties make it less vulnerable to fracture from accidental shock or high-acceleration flights. Due to these attributes, widespread adoption of APCP and related propellant types in

231-467: Is charged with the responsibility (by the NAR and TRA) to check hobbyists for high-power rocket certification before a sale can be made. The amount of APCP that can be purchased (in the form of a rocket motor reload) correlates to the impulse classification, and therefore the quantity of APCP purchasable by a hobbyist (in any single reload kit) is regulated by the NAR and TRA. The overarching legality concerning

264-450: Is heavily dependent on mean AP particle size as the AP absorbs heat to decompose into a gas before it can oxidize the fuel components. This process may be a rate-limiting step in the overall combustion rate of APCP. The phenomenon can be explained by considering the heat-flux-to-mass ratio: As the particle radius increases the volume (and, therefore, mass and heat capacity) increases as the cube of

297-800: Is in solid rocket propellant . It binds the oxidizing agent , fuel and other ingredients into a solid but elastic mass in most composite propellant systems. The cured polyurethane acts as a fuel in such mixtures. For example, HTPB is used in all 3/4 stages of the Japanese M-5 launch vehicles and in 1/3 stages of Indian PSLV launch vehicle. JAXA describes the propellant as "HTPB/AP/Al=12/68/20", which means, proportioned by mass, HTPB plus curative 12% (binder and fuel), ammonium perchlorate 68% (oxidizer), and aluminum powder 20% (fuel). Similar propellants, often referred to as APCP ( ammonium perchlorate composite propellant ) are used in larger model rockets. A typical APCP propellant mixture produces 2–3 times

330-511: Is not required in APCP, most formulations include at least a few percent as a combustion stabilizer, propellant opacifier (to limit excessive infrared propellant preheating), and increase the temperature of the combustion gases (increasing I sp ). Though increasing the ratio of metal-fuel to oxidizer up to the stoichiometric point increases the combustion temperature, the presence of an increasing molar fraction of metal oxides, particularly aluminium oxide (Al 2 O 3 ) precipitating from

363-494: Is often mitigated by reducing aluminium particle size, inducing turbulence (and therefore a long characteristic path length and residence time), and/or by reducing the aluminium content to ensure a combustion environment with a higher net oxidizing potential, ensuring more complete aluminium combustion. Aluminium combustion inside the motor is the rate-limiting pathway since the liquid-aluminium droplets (even still liquid at temperatures 3,000 K (2,730 °C; 4,940 °F)) limit

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396-477: The Space Shuttle missions, in which APCP was used for the two SRBs. The composition of APCP can vary significantly depending on the application, intended burn characteristics, and constraints such as nozzle thermal limitations or specific impulse (I sp ). Rough mass proportions (in high-performance configurations) tend to be about 70/15/15 AP/HTPB/Al, though fairly high performance "low-smoke" can have compositions of roughly 80/18/2 AP/HTPB/Al. While metal fuel

429-437: The combustion chamber . The combustion time of the aluminium particles in the hot combustion gas varies depending on aluminium particle size and shape. In small APCP motors with high aluminium content, the residence time of the combustion gases does not allow for full combustion of the aluminium and thus a substantial fraction of the aluminium is burned outside the combustion chamber, leading to decreased performance. This effect

462-421: The high-power rocketry community regularly uses APCP in the form of commercially available propellant "reloads", as well as single-use motors. Experienced experimental and amateur rocketeers also often work with APCP, processing the APCP themselves. Ammonium perchlorate composite propellant is a composite propellant, meaning that it has both fuel and oxidizer combined into a homogeneous mixture, in this case with

495-473: The specific impulse of the black powder propellant used in most smaller rocket motors. HTPB is also used as a hybrid rocket fuel. With N 2 O ( nitrous oxide , or "laughing gas") as the oxidizer, it is used to power the SpaceShipTwo hybrid rocket motor developed by SpaceDev . The land speed record attempt Bloodhound SSC was to have used HTPB with a high-test peroxide oxidizer, but that plan

528-435: The AP and Al, Al will often take an interstitial position in a pseudo-lattice of AP particles. APCP deflagrates from the surface of exposed propellant in the combustion chamber. In this fashion, the geometry of the propellant inside the rocket motor plays an important role in the overall motor performance. As the surface of the propellant burns, the shape evolves (a subject of study in internal ballistics), most often changing

561-566: The APCP " grains " (cylinders of propellant) are loaded into the reusable motor casing along with a sequence of insulator disks and o-rings and a ( graphite or glass-filled phenolic resin ) nozzle. The motor casing and closures are typically bought separately from the motor manufacturer and are often precision-machined from aluminium. The assembled RMS contains both reusable (typically metal) and disposable components. The major APCP suppliers for hobby use are: To achieve different visual effects and flight characteristics, hobby APCP suppliers offer

594-728: The United States, APCP for hobby use is regulated indirectly by two non-government agencies: the National Association of Rocketry (NAR), and the Tripoli Rocketry Association (TRA). Both agencies set forth rules regarding the impulse classification of rocket motors and the level of certification required by rocketeers in order to purchase certain impulse (size) motors. The NAR and TRA require motor manufacturers to certify their motors for distribution to vendors and ultimately hobbyists. The vendor

627-643: The aerospace industry. Ammonium perchlorate composite propellant is typically for aerospace rocket propulsion where simplicity and reliability are desired and specific impulses (depending on the composition and operating pressure ) of 180–260 s (1.8–2.5 km/s) are adequate. Because of these performance attributes, APCP has been used in the Space Shuttle Solid Rocket Boosters , aircraft ejection seats , and specialty space exploration applications such as NASA's Mars Exploration Rover descent stage retrorockets . In addition,

660-421: The application and desired thrust curve : While the surface area can be easily tailored by careful geometric design of the propellant, the burn rate is dependent on several subtle factors: In summary, however, most formulations have a burn rate between 1–3 mm/s at STP and 6–12 mm/s at 68 atm. The burn characteristics (such as linear burn rate) are often determined prior to rocket motor firing using

693-957: The chain terminated with a hydroxyl [OH] group: R-45HTLO has a functionality of 2.4-2.6, which means that there is (approximately) one additional hydroxyl group located along the chain for every two oligomeric units. This provides side-to-side linkage for a stronger cured product. HTPB is usually cured by an addition reaction with di- or poly- isocyanate compounds. Polyurethanes prepared from HTPB can be engineered for specific physical properties; polyurethanes may be highly elastic or tough and rigid. Some products include: rigid foam insulation panels; durable elastomeric wheels and tires (used for roller coasters , escalators , skateboards , etc.); automotive suspension bushings ; electrical potting compounds; high-performance adhesives ; surface coatings and surface sealants; synthetic fibers (e.g., Spandex ); carpet underlay; hard-plastic parts (e.g., for electronic instruments). An important application of HTPB

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726-440: The condensation of atmospheric moisture in the plume and this enhances the visible signature of the contrail. This visible signature, among other reasons, led to research in cleaner burning propellants with no visible signatures. Minimum signature propellants contain primarily nitrogen-rich organic molecules (e.g., ammonium dinitramide ) and depending on their oxidizer source can be hotter burning than APCP composite propellants. In

759-436: The gaseous solution creates globules of solids or liquids that slow down the flow velocity as the mean molecular mass of the flow increases. In addition, the chemical composition of the gases changes, varying the effective heat capacity of the gas. Because of these phenomena, there exists an optimal non-stoichiometric composition for maximizing Isp of roughly 16% by mass, assuming the combustion reaction goes to completion inside

792-437: The hobby has significantly enhanced the safety of rocketry. The exhaust from APCP solid rocket motors contains mostly water , carbon dioxide , hydrogen chloride , and a metal oxide (typically aluminium oxide ). The hydrogen chloride can easily dissolve in water and create corrosive hydrochloric acid . The environmental fate of hydrogen chloride is not well documented. The hydrochloric acid component of APCP exhaust leads to

825-551: The implementation of APCP in rocket motors is outlined in NFPA 1125. Use of APCP outside hobby use is regulated by state and municipal fire codes. On March 16, 2009, it was ruled that APCP is not an explosive and that manufacture and use of APCP no longer requires a license or permit from the ATF . Hydroxyl-terminated polybutadiene Hydroxyl-terminated polybutadiene ( HTPB ) is an oligomer of butadiene terminated at each end with

858-402: The pressure would reach an internal equilibrium. This isn't to say that APCP cannot cause an explosion , just that it will not detonate. Thus, any explosion would be caused by the pressure surpassing the burst pressure of the container (rocket motor). Commercial APCP rocket engines usually come in the form of reloadable motor systems (RMS) and fully assembled single-use rocket motors. For RMS,

891-430: The propellant before use. The perchlorate serves as the oxidizer , while the binder and aluminium serve as the fuel . Burn rate catalysts determine how quickly the mixture burns. The resulting cured propellant is fairly elastic (rubbery), which also helps limit fracturing during accumulated damage (such as shipping, installing, cutting) and high acceleration applications such as hobby or military rocketry. This includes

924-510: The propellant surface area exposed to the combustion gases. The mass flux (kg/s) [and therefore pressure] of combustion gases generated is a function of the instantaneous surface area A s {\displaystyle A_{\text{s}}} (m ), propellant density ρ {\displaystyle \rho } (kg/m ), and linear burn rate b r {\displaystyle b_{r}} (m/s): Several geometric configurations are often used depending on

957-420: The radius. However, the surface area increases as the square of the radius, which is roughly proportional to the heat flux into the particle. Therefore, a particle's rate of temperature rise is maximized when the particle size is minimized. Common APCP formulations call for 30–400 μm AP particles (often spherical), as well as 2–50 μm Al particles (often spherical). Because of the size discrepancy between

990-426: The reaction to a heterogeneous globule interface, making the surface area to volume ratio an important factor in determining the combustion residence time and required combustion chamber size/length. The propellant particle size distribution has a profound impact on APCP rocket motor performance. Smaller AP and Al particles lead to higher combustion efficiency but also lead to increased linear burn rate. The burn rate

1023-416: Was provided by means of a liquid injection thrust vector control (LITVC) system, with an external nacelle containing nitrogen tetroxide attached to the side of each booster. Solid fueled separation rockets, used to jettison the spent boosters, were affixed at the top and bottom of the stage. Thrust-termination capability, necessary for crewed rockets such as the Space Shuttle or Manned Orbiting Laboratory ,

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1056-414: Was to be provided by two pyrotechnically triggered ports on the forward closure, which when opened would allow for the non-propulsive venting of exhaust gasses. The forward end of the stage contained an aerodynamic nose cone , an ignitor, separation rockets, and the forward attachment ring. The aft end contained additional separation rockets, the nozzle, and a heat shield. The overall design of each variant

1089-484: Was very similar, the main difference being the number of segments used. This is indicated by the number at the end of each designation. UA1205 was flown between 1982 and 1992, and used as a strap-on booster on the Titan IIIC , Titan 23C , Titan IIID , and Titan IIIE rockets, besides being proposed for use on several derivatives of the Saturn rocket family . The UA1206 was flown between 1982 and 1992, and used as

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