Kirsty L. Veale

The Phoenix Hybrid Sounding Rocket Program: A Progress Report

The University of KwaZulu-Natal’s Phoenix Program aims to develop a hybrid sounding rocket capable of reaching 100 km apogee by 2016. The first stage of the program is the development of the Phoenix-1A low altitude vehicle, capable of delivering a 1 kg payload to an altitude of 10 km. The vehicle’s aerodynamic and structural designs have been optimized for transonic flight and the manufacture of structural components has commenced. This paper outlines the geometric design, computational analyses and manufacturing techniques associated with critical structural components of the vehicle. These include the composite airframe and fins, internal bulkheads, oxidizer tank, injector bulkhead, combustion chamber casing, and motor nozzle assembly. The integration of the payload and recovery system is also discussed. The effects of various design solutions on the simulated vehicle performance have been investigated using the custom-developed Hybrid Rocket Performance Simulation or HYROPS software. The immediate objectives of the program are to begin static testing of the Phoenix-1A flight motor by October 2011 and to start flight testing of the vehicle in early 2012.

Flight Test of the Phoenix-1A Hybrid Rocket

The Phoenix-1A hybrid rocket is a low-altitude demonstrator developed by the Aerospace Systems Research Group (ASReG) at the University of KwaZulu-Natal (UKZN). In August 2013 the hybrid motor was successfully fired in a static ground test to determine its performance. Thereafter, the vehicle airframe and onboard systems were completed and the rocket was transported to Denel Overberg Test Range in the Western Cape where it was flight-tested in 2014. The launch campaign encompassed three technical objectives: to test the Phoenix program’s ground support equipment, to evaluate the launch countdown procedures and to test the vehicle itself. In addition, the campaign served to benefit ASReG’s human capital development program through the inclusion of former and current graduate students as part of the launch team. This paper describes the Phoenix-1A flight test which was monitored by an extensive array of tracking cameras and radars. The vehicle achieved an apogee of 2.5 km but suffered damage to its nozzle during launch. The probable cause of the damage is discussed, along with the outcome of each of the test objectives.

Structural Performance of Large Scale Paraffin Wax Based Fuel Grains

Paraffin wax has been identified as a high regression rate, liquefying fuel that can be used with nitrous oxide and other oxidizers as the solid component of a hybrid rocket propellant combination. The low viscosity and low surface tension of certain liquefying fuels allows for the development of small surface wave formations, and droplet entrainment into the oxidizer stream during the combustion process. This is the main contributing factor to the increased regression rate when compared to commonly used hybrid fuels such as HTPB and HDPE . Although significant work has been conducted in the field of combustion analysis of liquefying fuels, little investigation has been done on the structural performance of large scale grains. This paper investigates the structural performance of a pure paraffin wax fuel grain on the Phoenix-1A hybrid rocket and the proposed grain design of the larger Phoenix-2A vehicle. UKZN’s in-house Hybrid Rocket Performance Simulator software, HYROPS, is used to facilitate loading and regression rate predictions. Flight data from the Phoenix-1A launch is also considered along with an analysis of unconsumed grain that remained after motor burnout.

Preliminary Design of the Phoenix-1B Hybrid Rocket

Following the launch of UKZN’s Phoenix-1A hybrid rocket in August 2014, a revised vehicle design is now under consideration to replace the P-1A technology demonstrator. Designated P-1B, the 13 km apogee workhorse is to be less expensive and easier to manufacture so as to provide a reliable launch system for ongoing research into hybrid propulsion technology and to promote human capital development in aerospace design and launch operations. Using UKZN’s in-house tools (the Hybrid Rocket Performance Simulator (HYROPS) and Hybrid Rocket Performance Code (HRPC)), the rocket will be designed to take into account the lessons learnt in the P-1A program. This paper outlines the progress made to date in the design of Phoenix-1B’s nitrous oxide/aluminum-paraffin wax hybrid motor.

Optimization via “De - Turbulating” Spoked Wheels of a Solar Car

The aerodynamic efficieny of competitive renewable energy cars, such as the UKZN solar car, is one critical aspect to consider. The potential for improving the aerodynamics of the spoked wheels by enclosing them is investigated. A constraint of this analysis was that the bulk geometry of the components could not be altered. Smooth and dimpled wheel covers allow for, the mitigation of turbulence and reduction in pressure differential across the wheel caused by the spokes. Substantial geometry simplification is required for complex fluid domains such as the one analyzed here. The designs, projected effects, manufacture and application of smooth and dimpled wheel covers is described, results imply that further optimization of the dimpled wheel covers may allow for a further gain in aerodynamic efficiency. The gain in aerodynamic efficiency is then compared to the added effect of rolling resistance caused by the added mass of the covers in order to establish a net gain in efficiency. Entire car models incorporating wheel covers were not successfully analyzed, this was due to the need for such an analysis not being necessary.