The development of an infrastructure for end-to-end hybrid rocket flight simulation, motor and aerodynamic prediction and testing, and design analysis.

The foundations for simulation and testing of hybrid rockets at Utah State University are presented. The testing and analysis was motivated by the participation of Utah State University in the 2007-2008 University Student Launch Initiative. Due to the requirements of the competition, a 6 degree of freedom flight simulator, a motor simulator, wind tunnel and rocket motor test facilities were developed to better characterize the rocket entered into the 2007-2008 USLI competition. This effort also improved the resources for rocket design, research and testing at Utah State University

Correlation of Hybrid Rocket Propellant Recession Measurements with Enthalpy-Balance Model Predictions

An enthalpy-balance fuel-grain regression model is presented. The regression model, based on the longitudinally averaged fuel recession rates, is shown to accurately predict the chamber pressure, thrust and specific impulse performance of small and medium scale hybrid rocket motors. The key to the model predictions is the longitudinal enthalpy balance between the fuel grain heat of ablation and the convective heat transfer from the flame zone to the model surface. Convective heat transfer is related to the surface skin friction using the Reynolds analogy for turbulent flow. Simple flat plate models are used to predict the longitudinally averaged skin friction coefficient. Chemical properties of the combustion products were evaluated using the NASA Computer Equilibrium with Applications (CEA) Combustion code. Model predictions for a nitrous oxide (N2O) and hydroxyl-terminated poly butadiene (HTPB) motor are compared to data from a small-scale test firing with a 4- inch diameter motor. Suggestions for model improvements are offered

Development and Flight Testing of Energy Management Algorithms for Small-Scale Sounding Rockets

The development, implementation, and ight results for a navigation algorithm and an energy management system are presented. The navigation algorithm employs both a Kalman lter and an inertial navigation routine. The energy management system includes an asymptotic targeting algorithm and pneumatically deployed air brakes that deplete excess energy from the rocket in ight. These algorithms were developed to ful ll objectives in the NASA USLI competition. The energy management algorithm has been shown to successfully target an apogee altitude on two separate test ights

gRNAid : a tool for the comparative analysis of RNA secondary structures

The secondary structure of a 16S rRNA molecule is a graphical, two dimensional representation used by molecular biologists in determining evolutionary relationships between different organisms. By comparing two secondary structures, scientists can obtain knowledge of how 'related' one species of bacteria may be to another species [OLSE 1986]. To date, there is no widely used computer program for secondary structure creation because these programs generally do not work well with large sets of sequence data. In other words, these programs work adequately on small RNA fragments, but tend to create incorrect or unwieldy secondary structures on larger data sets. Thus, the molecular biologist is forced to create the secondary structure by hand, which is a monotonous and time consuming task. The gRNAid program is a tool implemented for the Macintosh that will aid in the creation of secondary structures. Rather than trying to calculate the molecular bonding in order to form the structure, gRNAid looks at a known secondary structure and uses it as a template to create a new secondary structure for another organism

Design of a Small Scale Aerospike Nozzle and Associated Testing Infrastructure for Experimental Evaluation of Aerodynamic Thrust Vectoring

A system for cold flow testing of an aerospike nozzle has been developed in an effort to examine the effectiveness of aerodynamic thrust vectoring and truncated nozzle base bleed. These tests are designed to produce result that will support the design of a system for hot flow testing of the same technologies. Design of a nozzle suitable for testing with reasonable cold-gas mass flow rates and measureable forces and moments involved an extensive parametric study. Conceptual-level computational fluid dynamics results for aerodynamic thrust vectoring and base bleed are also described

Analytical and Experimental Evaluation of Aerodynamic Thrust Vectoring on an Aerospike Nozzle

Results from numerical and cold-flow experimental investigations of aerodynamic thrust vectoring on a small-scale aerospike thruster are presented. Thrust vectoring was created by the injection of a secondary fluid into the primary flow field normal to the nozzle axis. The experimental aerospike nozzle was truncated at 57% of its full theoretical length. Data derived from cold-flow thrust vectoring tests with carbon dioxide as the working fluid are presented. Injection points near the end of the truncated spike produced the highest force amplification factors. Explanations are given for this phenomenon. For secondary injection near the end of the aerospike, side force amplification factors up to approximately 1.4 and side force specific impulses up to approximately 55 s with main flow specific impulses clustering around 38 s were demonstrated. These forces crisply reproduce input pulses with a high degree of fidelity. The side force levels are approximately 2.7% of the total thrust level at maximum effectiveness. Higher side forces on the order of 4.7% of axial thrust were also achieved at reduced efficiency. The side force amplification factors were independent of operating nozzle pressure ratio for the range of chamber pressures used in this test series

The Multiple Use Plug Hybrid for NanoSats (MUPHyN) Miniature Thruster

The Multiple Use Plug Hybrid (for) Nanosats is a prototype thruster is being developed to fill a niche application for NanoSat-scale spacecraft propulsion. When fully developed, the MUPHyN thruster will provide an effective and low-risk propulsive capability that could enable multiple NanoSats to be independently re-positioned after deployment from a parent launch vehicle. Because the environmentally benign, chemically-stable propellants are mixed only within the combustion chamber after ignition and the flow rate of the fuel is determined by a pyrolysis mechanism that is nearly independent of pressure or fuel grain defects, the system is inherently safe and can be piggy-backed near a secondary payload with little or no overall mission risk increase to the primary payload. The MUPHyN thruster uses safe-handling and inexpensive nitrous oxide (N2O) and acrylonitrile-butadiene-styrene (ABS) as propellants. Fused Deposition Modeling (FDM), a direct digital manufacturing process, is used to fabricate short-form-factor solid fuel grains with multiple helical combustion ports from ABS thermoplastic. This manufacturing process allows for the rapid development and manufacture of complex fuel grain geometries that are not possible to extrude or cast using conventional methods. This technology enables the construction of fuel grains with length-to-diameter ratios appropriate for incorporation into CubeSats while maintaining high surface areas and regression rates that allow the system to maintain a near optimal oxidizer to fuel ratio. The MUPHyN system provides attitude control torques by using secondary-injection thrust vectoring on a truncated aerospike nozzle. This configuration allows large impulse delta V burns and small impulse attitude control firings to be performed with the same system. To ensure survivability during extend duration burns, the MUPHyN incorporates a novel regenerative cooling design where the N2O oxidizer flows through a cooling path embedded in the aerospike nozzle before being injected into the combustion chamber near the nozzle base

Development and Testing of a Green Monopropellant Ignition System

This paper will detail the development and testing of a "green" monopropellant booster ignition system. The proposed booster ignition technology eliminates the need for a pre-heated catalyst bed, a high wattage power source, toxic pyrophoric ignition fluids, or a bi-propellant spark ignitor. The design offers the simplicity of a monopropellant feed system features non-hazardous gaseous oxygen (GOX) as the working fluid. The approach is fundamentally different from all other "green propellant" solutions in the aerospace in the industry. Although the proposed system is more correctly a "hybrid" rocket technology, since only a single propellant feed path is required, it retains all the simple features of a monopropellant system. The technology is based on the principle of seeding an oxidizing flow with a small amount of hydrocarbon.1 The ignition is initiated electrostatically with a low-wattage inductive spark. Combustion gas byproducts from the hydrocarbon-seeding ignition process can exceed 2400 C and the high exhaust temperature ensures reliable main propellant ignition. The system design is described in detail in the Hydrocarbon-Seeded Ignition System Design subsection

UBRI Photometry of Globular Clusters in the Leo Group Galaxy NGC 3379

We present wide area UBRI photometry for globular clusters around the Leo group galaxy NGC 3379. Globular cluster candidates are selected from their B-band magnitudes and their (U-B)o vs (B-I)o colours. A colour-colour selection region was defined from photometry of the Milky Way and M31 globular cluster systems. We detect 133 globular cluster candidates which, supports previous claims of a low specific frequency for NGC 3379. The Milky Way and M31 reveal blue and red subpopulations, with (U-B)o and (B-I)o colours indicating mean metallicities similar to those expected based on previous spectroscopic work. The stellar population models of Maraston (2003) and Brocato etal (2000) are consistent with both subpopulations being old, and with metallicities of [Fe/H] \~ -1.5 and -0.6 for the blue and red subpopulations respectively. The models of Worthey (1994) do not reproduce the (U-B)o colours of the red (metal-rich) subpopulation for any modelled age. For NGC 3379 we detect a blue subpopulation with similar colours and presumably age/metallicity, to that of the Milky Way and M31 globular cluster systems. The red subpopulation is less well defined, perhaps due to increased photometric errors, but indicates a mean metallicity of [Fe/H] ~ -0.6.Comment: 12 pages, Latex, 10 figures, 1 table, submitted for publication in MNRAS, Fig. 11 available in source file or from [email protected]

On the sintering of single crystal rutile

The sintering of single crystal rutile spheres has been studied in air and in reducing atmosphere in the temperature range 900 to 1350[deg]C. The rate of sintering is characterized by two stages: a slow initial one, followed by a more rapid period. Simultaneously with the change in sintering rate, flat surfaces develop on the rutile spheres. It is suggested that this phenomenon is responsible for the change in sintering rate.From qualitative and quantitative evidence, it is concluded that surface diffusion is the transport process controlling sintering under the conditions of the present studies. The results of this investigation are at variance with those of previous studies. Possible reasons for the discrepancy are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33417/1/0000818.pd