Approved for public release; distribution is unlimited. / An autonomously guided rocket-powered delivery vehicle has been under development at the Naval Postgraduate School. Designed to eventually counter UAV swarm attacks, the vehicle made advances toward reaching a target in the sky. These advances reduced the time needed to launch, modify, and relaunch the rocket, while adding capabilities such as data transfer along the vehicle axis and the rapid download of flight data. Improving the vehicle included reconfiguring the guidance, navigation, and control (GNC) strategy. Advancements included the design, implementation, and evaluation of electronic servo control, actuating fins, and the mechanical coupling design. The forward compartment in the vehicle’s nose cone was structurally modified for the GNC equipment and to support electronics under high-g launch conditions. Modifications included innovative designs for managing heat transfer requirements. Using off-the-shelf subsystem components kept the advancements fiscally mindful. After implementing the design features, two final test launches were performed: one demonstrated a control spin rate of 8.5 rad/sec; the other showed the vehicle’s ability to execute pitch maneuvers on a single axis. The test results can be used to improve the GNC software and servo control parameters. Continued development will allow the system to become a viable option for countering UAV swarms. / Ensign, United States Navy

This study is dedicated to providing readers with a holistic overview of the phenomenon of the imitation among internet based companies. Four research questions have been posed and answered through qualitative primary and secondary researches. As a result of this study major success factors that allowed a Berlin - based company Rocket Internet SE to imitate ideas and business models of others have been identified, numerous recommendations have been provided to future copycat companies as well as to companies that face the pressure from such copycats in their day-to-day activities. As an outcome, more transparency has been provided about the processes of imitation in the business environment in order to allow various players to compete more effectively, structure their operations in more efficient way and avoid costly mistakes.

This thesis examines the impact of the physical contamination on optical surfaces of spacecraft by an ABS/GOX thruster. Plume contamination presents a significant operational hazard for spacecraft solar arrays and thermal control surfaces can lead to decreased power production and increased spacecraft temperatures. Historically, due to the lack of a reliable, on-demand, and multiple-use ignition methodology, hybrid rockets have never been previously considered for in-space propulsion. Recent advancements in hybrid rocket technologies, have made hybrid systems feasible for in space propulsion. However, prior to this study no research had ever been performed with regard to plume contamination effects due to hybrid rockets. This paper presents the results from a set of preliminary plume contamination measurements on a prototype small spacecraft hybrid rocket system, collected under both ambient and vacuum chamber conditions.

The Utah State University Propulsion Research Laboratory (USUPRL) has recently made significant developments in the area of hybrid rocket systems. This type of propulsion system incorporates a solid fuel and a gas or liquid oxidizer. Hybrid rocket systems are known for their inherent safety, reliability, and restart capability. Over the last several years, the USUPRL has successfully built and tested a hybrid rocket system comprising acrylonitrile butadiene styrene (ABS) plastic and gaseous oxygen (GOX). The system was demonstrated to be fully functional during ground, vacuum, and sub-orbital flight testing. Continuing forward, the USUPRL endeavors to extend the capabilities of this hybrid rocket system to in-space propulsion applications, such as an attitude control systems (ACS). This thesis investigates the feasibility of using the USU Green Hybrid Rocket as an ACS for an intermediate-sized launch vehicle. A computer simulation was developed to demonstrate the control and stability of the spacecraft under the influence of the ACS.

Steady state and transient maneuver problems for a high performance fighter aircraft with and without thrust vectoring are investigated. The steady state aspect of these studies determines control combinations with and without thrust vectoring which optimize selected level-flight point performance criteria including minimum speed, maximum instantaneous range, and maximum sustained turn rate. The transient maneuvers are initiated from straight and level flight and include a longitudinal pitch-up to a desired fuselage pointing angle and a lateral-directional transition (wind-up) to a desired steady level turn rate. For the transient maneuvers, a full six-degree-of-freedom model of the aircraft is used with three conventional aerodynamic controls, throttle control and pitch and yaw thrust vectoring control. Each of the control time histories are parameterized so as to include both the rate and range limits of the controls. A nonlinear programming algorithm is used to determine the control parameter values which yield the minimum time to execute the prescribed maneuvers. Results indicate that thrust vectoring does not significantly change the steady state behavior in the scenarios investigated. However, flight times for the transient maneuvers are found to be reduced by up to 28%. The greatest effect of thrust vectoring occurs at low Mach number. / Master of Science

A water analogy technique was used in this investigation of the flow field in the pulse I motor of a two-pulse solid rocket motor. A full scale model of clear acrylic material was constructed to allow direct visual access of the flow field. The experiment, which was conducted with one of the VPI water analogy rigs, simulated the flow in the spent pulse I motor chamber after the pulse Il motor would have been ignited. The relations between the pattern and angle of the throughflow holes on the bulkhead--which separates the two motor chambers--and the downstream flow pattern in the pulse I chamber were assessed by changing the bulkhead model configuration for each test. Video records of the flow pattern were obtained through flow visualization tests, which used either fluorescein dye or air bubbles as the tracer. Also, hot water tests with thermocouple measurements were conducted as a means of investigating the rate of mixing of the propellent from the pulse Il motor with the gases in the pulse I motor chamber, as well as the migration of the pulse Il propellent along the wall of the pulse I motor casing. The test data show a clear relation between the hole arrangement on the bulkhead and the ensuing downstream flow pattern, as well as the rate of mixing along the wall of the pulse I motor casing. Consequently, the results provide directions for improving the performance of heat transfer insulation material on the wall of the pulse I motor through a prudent choice of the hole arrangement on the bulkhead. / Master of Science

The objective of this thesis was to select a star for observation and determine the error in the retrieval technique for a rocket experiment to measure lower thermospheric Nitric Oxide in the polar night using stellar occultation technique. These objectives are accomplished by planning the geometry, determining the requirements for observations, window for launch and discussing the retrieval technique. The planning is carried out using an approximated (no drag) and simulated rocket trajectory (provided by NSROC: NASA Rocket Operations Contract). The simulation for the retrievals is done using data from Student Nitric Oxide Explorer. Stars were taken from a catalogue called TD1. Launch times were obtained from the geometry planned resulting from selecting a zenith angle after choosing a maximum occultation height and determining rocket apogee. Window for observing Spica was found to be 20 minutes. The retrieval technique and simulations showed that column densities and volume densities should be retrievable to less than 5% and 20% respectively observing occultation heights 90-120km. The study suggests that choosing a star positioned north w.r.t the observation location gives us more poleward latitudes and larger launch window. Future research can be carried out applying the stellar occultation and retrieval technique to a satellite. / Master of Science

A long hollow cylinder with five layers, subjected to a random thermal environment is analyzed. The random thermal environment includes the ambient air temperature, solar radiation and wind speed. The location of interest is Phoenix, Arizona. The governing differential equation is the so-called one-dimensional Fourier heat conduction equation in cylindrical coordinates. An implicit finite difference scheme is developed to obtain temperature responses inside the cylinder. Given the linear elastic behavior of materials involved, induced stresses and strains are evaluated at the end of each time step of the finite difference scheme. A statistical analysis is then carried out to determine the probability of failure of the propellant and hence the service life of the motor can be computed. / Ph. D.

A series of frozen stress experiments were conducted on surface flaws of varying aspect ratios in pressurized cylinder with star-shaped cutout in order to study the stress intensity factor distribution along the flaw border and to estimate the loss of the inverse square root singularity when the crack border intersects the inner star surface at right angles. By applying a refined optical method, the photoelastic data are converted into classical stress intensity factors resulting from the three dimensional stress state existing at the inner surface and compared with a numerical analysis to indicate the nearly uniform distribution of the stress intensity factor along the crack border. Based upon this result a two dimensional weight function approach is demonstrated to yield accurate values of the maximum stress intensity factor for the motor grain test geometry. / Ph. D.

Student Number : 0105159R - MSc(Eng) Dissertation - School of Electrical and Information Engineering - Faculty of Engineering and the Built Environment / This dissertation presents the design of a re-usable rocket for use in triggered-lightning experiments. It is intended that the rocket will tow a thin wire to sufficient height so that the lightning mechanism will attach onto the wire and follow it to ground. The rocket design is inherently safe as it does not use explosive materials for its propulsion system, and hence conforms to South African explosive legislation. The designed rocket consists of a hybrid motor, which uses a solid combustion chamber and liquid oxidiser rather than solid motors which use a single solid fuel or a liquid motor which uses two liquid propellants. The mechanical performance of the oxidiser stage is critical in containing the pressurised oxidiser and regulating the flow of the oxidiser into the combustion chamber. The design of the combustion chamber and the rate at which the solid material burns is key to the generation of the pressure which is expelled through the nozzle to produce thrust. The design of the nozzle is covered in which the material from which it is made must withstand temperatures in excess of 1600 ◦C. The entire system was modelled to calculate the parameters of the various subsystems. The simulation study shows that the rocket will be able to reach 1 km with a complete section of wire towed behind it. A cost analysis, against other commercial rocket systems, was performed. The analysis concludes from the total cost of ownership that it is significantly cheaper to operate the designed rocket, over the course of the experiment, than other rocket systems.