Supergun - Project HALO Supergun - Project HALO Multidisciplinary Design Project – Final Report Aidan Cookson, Jack Feakins, Kin Man Benjamin Lee, Sophie McElhill, Alex Oses, Eleri Williams 19/01/2015 FAO: Prof. Roger Webb, Prof. Neil Downie, Dr. Chris Bridges & Dr. Ignazio Cavarretta Supergun - Project HALO EXECUTIVE SUMMARY The ‘supergun’ launch method has long been coveted as an economic alternative to conventional rocket launches. The method utilises a large powerful gun to deliver a satellite payload into orbits around the Earth. The idea was first proposed in Isaac Newton’s ‘A Treatise of the System of the World’ in 1728 and with the first significant experiments conducted by Gerald Bull in the High Altitude Research Project (HARP) in 1966. The HARP project achieved a record non-rocket launch reaching an altitude of 180 km with a 180 kg projectile at a speed of 3,600 m s-1. Project HALO (Hydrogen Assisted Launch to Orbit) is a $27 million USD proposal for delivering small CubeSat payloads to Low Earth Orbit, using modern hydrogen light gas gun technology, assisted by an innovative hybrid rocket; rejuvenating the supergun launch strategy for the 21st century and beyond. The philosophy of Project HALO is ‘a supergun for the small masses’, echoing our commitment to providing a regular, reliable and reactive service in their pursuit to advance scientific research and development from space. The current prevailing launch method for small satellites, such as CubeSats, is facilitated by attaching the satellites as a secondary payload to a large multi-stage rocket costing $100000 USD per 1U CubeSat. These large multi-stage rocket launches are irregular, complex and not tailored to the small satellite market. Project HALO will offer a flexible launch schedule for delivering payloads to a range of Low Earth Orbits at a rate of $120000 USD per 1U CubeSat. The Owen Stanley Mountain Range in Papua New Guinea has been selected to host the Project HALO supergun due to optimal launch conditions. This location provides reduced drag due to its high altitude, added initial speed due to the near equatorial prime location, and immediate proximity to the Pacific Ocean mitigating dangerous fallout in the case of mission abort. The HALO gun uses hydrogen due to its low molecular weight, leading to a lower pressure drop behind the projectile, offering the highest muzzle velocity of any practical gun architecture. To achieve this muzzle velocity a two-stage hydrogen light gas gun configuration is used. The gun barrel was designed to be a maximum of 300 m long due to feasibility of construction and transportation of the barrel to the launch site. Limiting the length of the barrel increases the acceleration forces experienced by the projectile and payload; this significant trade-off defined the project. After the selection of a 300 m long gun barrel, the design initiative of the group was to produce a feasible supergun in tandem with a projectile that can survive the harsh launch conditions, and can be visualised in simulations to achieve the desired orbit. An iterative design process was used to concurrently develop the rocket and projectile by use of simulation and CAD respectively. The trajectory simulation accounted for many factors yielding realistic data providing the group with a design base, from which the projectile, rocket and gun could be scaled from initial approximations. i Executive Summary Supergun - Project HALO With each iteration of the design process, the gun design was impacted due to increasing projectile mass. The final wet mass of the projectile of 3424 kg represents a workable and realistic design for launching at 6 km s-1 and surviving an average acceleration of 6126 g while maintaining the lowest possible mass and containing the required fuel to achieve orbit. The projectile is mainly comprised of ceramic matrix composites and carbon-carbon composites, as these materials exhibit necessary characteristics such as high compressive strength, low density and low thermal conductivity. The profile of the projectile has also been designed to reduce aerodynamic drag in order to reduce the fuel required to reach orbit. To reduce projectile mass further, the avionics of the CubeSat satellite payload is utilised in part to perform the role of projectile avionics. This leads to a mass saving of approximately 5 kg in avionics, which results in further significant savings in rocket propellant and total projectile mass. The rocket engine has been designed to give the remaining delta-v required to reach orbit using hybrid propellant technology; the engine uses solid paraffin fuel with liquid oxygen as the oxidiser. The proposed design uses LOX boil-off as a weight saving mechanism to self-pressurise the oxygen tank compared with conventional methods which require an additional gas tank, valves, pumps and insulated piping. Further design parameters have been adjusted to give the most efficient and feasible design within the size constraints of the gun barrel. The need to increase the projectile mass to cope with the high g launch has led to an impractical light gas gun design. To achieve the required muzzle velocity a multi-injection architecture has been used. The maximum realistic projectile mass determined with this design has been calculated as approximately 2000 kg. This projectile mass leads to a maximum total gun length of 500 m, a maximum pump tube length of 150 m and a maximum pressure of 290 MPa. However, for the projectile to survive the g-force experienced from launch and the extreme conditions experienced from hypersonic flow a realistic, high-strength design gives a subsequent mass of 3424 kg. The gun design constraints therefore result in a required total gun length of 1100 m with a maximum internal pressure of 370 MPa which is both structurally and environmentally impractical. For the project to progress, a lower g and a lower muzzle velocity should be targeted through the use of hydrogen gun or alternative technologies. ii Executive Summary Supergun - Project HALO ACKNOWLEDGEMENT We would like to take this opportunity to express our warm thanks to Professor Neil Downie, Dr Chris Bridges and Dr Ignazio Cavarretta, for supervising this Multidisciplinary Design Project. Professor Neil Downie always supplied innovative ideas and industry updates, Dr Chris Bridges delivered cutting edge avionics technology knowledge and Dr Ignazio Cavarretta provided us with constructive recommendations on civil construction and advised on many mechanical design challenges. iii Acknowledgement Supergun - Project HALO CONTENTS Executive Summary........................................................................................................................... i Acknowledgement ........................................................................................................................... iii Contents ........................................................................................................................................... iv List Of Figures ................................................................................................................................. ix List Of Tables ................................................................................................................................. xii Nomenclature ................................................................................................................................ xiii Abbreviations and Acronyms ........................................................................................................ xvi Units ............................................................................................................................................ xviii 1 Introduction .............................................................................................................................. 1 1.1 Scope of the Supergun Project.......................................................................................... 1 1.2 Interpretation of Design Brief........................................................................................... 1 1.3 Project Market .................................................................................................................. 2 2 Design Specification ................................................................................................................. 4 3 Location and Environment ....................................................................................................... 6 3.1 Considerations .................................................................................................................. 6 Requirements ............................................................................................................ 7 Locations Considered ............................................................................................... 7 Location Chosen ....................................................................................................... 8 Construction of the Gun ........................................................................................... 8 3.2 Other Launch Considerations ........................................................................................... 9 4 Gun and Recoil Design ........................................................................................................... 10 4.1 Gun Thermo-Fluids .......................................................................................................