Jonny Dyer

Skybox Imaging is building a constellation of high-resolution Earth imag- ing micro-satellites in order to revolutionize access to information about the changes happening across Earth. In 2013, Skybox launched its first satellite, SkySat-1 as the pathfinder to a constellation of small spacecraft.
We begin with a high-level overview of Skybox Imaging and its mission. Then we discuss the unique design approach at Skybox and the critical engineering ingredients that have enabled such a powerful… Show more

Skybox Imaging is building a constellation of high-resolution Earth imag- ing micro-satellites in order to revolutionize access to information about the changes happening across Earth. In 2013, Skybox launched its first satellite, SkySat-1 as the pathfinder to a constellation of small spacecraft.
We begin with a high-level overview of Skybox Imaging and its mission. Then we discuss the unique design approach at Skybox and the critical engineering ingredients that have enabled such a powerful spacecraft in a small package and at low cost.
Finally we discuss our plans for a constellation of small imaging satellites. Show less

Skybox recently became the first commercial company to baseline ECAPS’ High Performance Green Propulsion (HPGP) technology, implementing a propulsion system design with four 1N thrusters in their second generation small satellite platform (< 150 kg). The initial propulsion module, to be delivered in 2013, will serve to qualify the system design for use in an entire constellation of small satellites intended to provide customers easy access to reliable and frequent high-resolution images of… Show more

Skybox recently became the first commercial company to baseline ECAPS’ High Performance Green Propulsion (HPGP) technology, implementing a propulsion system design with four 1N thrusters in their second generation small satellite platform (< 150 kg). The initial propulsion module, to be delivered in 2013, will serve to qualify the system design for use in an entire constellation of small satellites intended to provide customers easy access to reliable and frequent high-resolution images of the Earth. Show less

An emerging class of small satellite missions requires assured operational lifetime and rapid development on a moderate budget. This paper describes a “Careful COTS” approach to component selection and testing to meet these needs. Commercial parts are selected based on best practices, and radiation tested to limits based on the modeled mission environment. High-energy proton testing allows simultaneous exploration of total dose, displacement damage, and some single-event effects.
The authors… Show more

An emerging class of small satellite missions requires assured operational lifetime and rapid development on a moderate budget. This paper describes a “Careful COTS” approach to component selection and testing to meet these needs. Commercial parts are selected based on best practices, and radiation tested to limits based on the modeled mission environment. High-energy proton testing allows simultaneous exploration of total dose, displacement damage, and some single-event effects.
The authors have developed these methodologies over the course of a number of successful low-earth orbit missions. Provided the lifetime dose is under 30 krad, a solution can probably be realized with commercial parts. Various case studies of commercial parts that have failed under this dose are given. Show less

The dynamic behavior in a hybrid rocket motor is established by a number of complicated nonlinear physical and chemical processes which could potentially lead to multiple equilibrium points for the motor operation. Depending on the stability of the equilibrium points, switching from one mode to the other during the course of the motor operation is a highly possible outcome. Even though these spontaneous shifts are commonly observed and reported in hybrids, no theoretical framework capable of… Show more

The dynamic behavior in a hybrid rocket motor is established by a number of complicated nonlinear physical and chemical processes which could potentially lead to multiple equilibrium points for the motor operation. Depending on the stability of the equilibrium points, switching from one mode to the other during the course of the motor operation is a highly possible outcome. Even though these spontaneous shifts are commonly observed and reported in hybrids, no theoretical framework capable of explaining this interesting behavior exists in the open literature at this time. It is important to note that the shifting of equilibrium points which is the subject of this study is quite different from the classical “DC-Shift” observed in solid and hybrid rockets. It is well established that the “DC-Shift” is an upward movement in the mean chamber pressure caused by large amplitude combustion oscillations. In this paper, we have developed a set of nonlinear dynamic models for the hybrid rocket system which allow for the possibility of multiple equilibrium points for the motor operation. These models have been used to establish the conditions required for switching between equilibrium points. Specifically, it has been shown that an inverse dependency between the motor efficiency and the injector pressure drop could lead to multimodal operation. Such a reverse correlation is physically plausible, since for a system that is already operating at a large injector pressure drop, any additional drop would lead to an increase in the jet break up distance. Under certain conditions hydraulic flipping of the injector orifice is also possible. Show less

The Peregrine Sounding Rocket Program is a joint program of NASA-Ames, NASA- Wallops, Stanford University and Space Propulsion Group, Inc. to develop and fly a high performance sounding rocket based on liquefying fuel hybrid rocket technology. The program was kicked off in November of 2006 and initial ground testing of the propulsion system begain in July 2008. Two virtually identical vehicles capable of lofting a 5kg payload to 100km will be constructed and flown out of the NASA Sounding… Show more

The Peregrine Sounding Rocket Program is a joint program of NASA-Ames, NASA- Wallops, Stanford University and Space Propulsion Group, Inc. to develop and fly a high performance sounding rocket based on liquefying fuel hybrid rocket technology. The program was kicked off in November of 2006 and initial ground testing of the propulsion system begain in July 2008. Two virtually identical vehicles capable of lofting a 5kg payload to 100km will be constructed and flown out of the NASA Sounding Rocket Facility at Wallops Island. The propellants utilized are nitrous oxide and paraffin, a high regression rate liquefying fuel initially developed at Stanford University. The goal of the Peregrine program is to demonstrate the operational maturity of liquefying hybrid propulsion systems for space applications and their potential to reduce propulsion system costs. This is the third in a series of three annual papers outlining the Peregrine project and providing status updates. The majority of this (JPC 2009) paper will focus on the results of the propulsion system ground test program and the detailed design of the vehicle. Show less

Even though N2O is a widely used energetic material, the number of decomposition related accidents are quite limited due to its abnormally slow decomposition kinetics. However hazards do exist especially in propulsion systems where large quantities of N2O are stored at room temperature in thin walled vessels. Moreover the closely coupled combustion chamber is a significant source for ignition which does not naturally exist in other applications. A detailed kinetics model for the N2O… Show more

Even though N2O is a widely used energetic material, the number of decomposition related accidents are quite limited due to its abnormally slow decomposition kinetics. However hazards do exist especially in propulsion systems where large quantities of N2O are stored at room temperature in thin walled vessels. Moreover the closely coupled combustion chamber is a significant source for ignition which does not naturally exist in other applications. A detailed kinetics model for the N2O decomposition process is presented. It is shown that a simplified single step first order kinetics model accurately captures the decomposition process at pressures larger than 40 atm. With use of the kinetics data, it has been shown that, at the same pressure and temperature, the N2O decomposition rate is six orders of magnitude slower than the decomposition of hydrogen peroxide (H2O2), making it a much safer propellant. Models for homogenous and local thermal ignition are also presented. It is shown that the estimated minimum ignition energy for pure N2O is approximately 450 mJ which is three orders of magnitude larger than the ignition energy for a stoichiometric CH4/air mixture. Small concentrations of diluents (i.e. N2, O2 or He) further increase the ignition energy making the mixture extremely difficult to ignite at dilution levels higher than 30%. The results of a model developed to predict the pressure rise in a closed vessel subject to decomposition is presented to demonstrate the significant hazard that exists in the N2O tank. The model predicts a 20 fold increase in pressure over a time period of many seconds for tanks that are in the range of 1-3 meters in length. Finally, a list of safety related recommendations unique to N2O operations have been included. The general conclusion is that despite its potential decomposition hazard, if handled properly, N2O is one of the safest oxidizers being used in rocket propulsion systems. Show less

The Peregrine Sounding Rocket Program is a joint basic research program of NASA Ames Research Center, NASA Wallops, Stanford University and the Space Propulsion Group, Inc. (SPG). The goal is to determine the applicability of liquifying hybrid technol- ogy to a small launch system. The approach is to design, build, test and fly a stable, efficient liquefying fuel hybrid rocket vehicle to an altitude of 100 km. The program was kicked off in October of 2006 and has seen considerable progress in… Show more

The Peregrine Sounding Rocket Program is a joint basic research program of NASA Ames Research Center, NASA Wallops, Stanford University and the Space Propulsion Group, Inc. (SPG). The goal is to determine the applicability of liquifying hybrid technol- ogy to a small launch system. The approach is to design, build, test and fly a stable, efficient liquefying fuel hybrid rocket vehicle to an altitude of 100 km. The program was kicked off in October of 2006 and has seen considerable progress in the subsequent 18 months. Two virtually identical vehicles will be constructed and flown out of the NASA Sounding Rocket Facility at Wallops Island. This paper presents the current status of the project as of June 2008. For background on the project, the reader is referred to last year’s paper. Show less

The Peregrine Sounding Rocket Program is a joint program of NASA Ames Research Center, NASA Wallops, Stanford University and the Space Propulsion Group, Inc. (SPG) to design, build, test and fly a liquefying fuel hybrid rocket vehicle to an altitude of 100 km. The program was kicked off in October of 2006 with initial ground testing of the propul- sion system to begin in September 2007 and first flight to be conducted in July 2008. Two virtually identical vehicles capable of lofting a 5 kg… Show more

The Peregrine Sounding Rocket Program is a joint program of NASA Ames Research Center, NASA Wallops, Stanford University and the Space Propulsion Group, Inc. (SPG) to design, build, test and fly a liquefying fuel hybrid rocket vehicle to an altitude of 100 km. The program was kicked off in October of 2006 with initial ground testing of the propul- sion system to begin in September 2007 and first flight to be conducted in July 2008. Two virtually identical vehicles capable of lofting a 5 kg payload will be constructed and flown out of the NASA Sounding Rocket Facility at Wallops Island. The propellants utilized will be nitrous oxide and SP1x01, a high regression rate, paraffin-based liquefying fuel initially developed by Dr. Arif Karabeyoglu at Stanford University. The goals of the Peregrine program include demonstrating the operational maturity of liquefying hybrid propulsion systems for space applications, utilizing a lean and efficient engineering team to keep cost down and progress on schedule, and paving the way for future large-scale hybrid propulsion work at Stanford University, NASA Ames and SPG. This paper is divided into sections describing project goals, programmatic details, initial vehicle design and progress to-date on the propulsion ground test phase of the program. Show less

Self-pressurizing propellants have some very attractive attributes for the propulsion sys- tem designer. The high vapor pressure at low temperatures of oxidizers such as nitrous oxide and fuels such as ethane allow these propellants to be used efficiently without the need for an external pressurant and the associated complexity and mass. However, performance prediction for self-pressurized systems is made more difficult due to the complex thermo- dynamics and mass transfer kinetics inherent in… Show more

Self-pressurizing propellants have some very attractive attributes for the propulsion sys- tem designer. The high vapor pressure at low temperatures of oxidizers such as nitrous oxide and fuels such as ethane allow these propellants to be used efficiently without the need for an external pressurant and the associated complexity and mass. However, performance prediction for self-pressurized systems is made more difficult due to the complex thermo- dynamics and mass transfer kinetics inherent in a two-phase system. Further complications arise from the fact that at pressures useful for a propulsion system the incompressible as- sumption is not valid for the liquid phase and the ideal gas assumption is not appropriate for the vapor phase. This work describes the culmination of the modeling done to date at Stanford University and NASA Ames for self pressurized propellant thermodynamics and fluid mechanics. A fundamental relation explicit in the Helmholtz energy is used in these models to provide very accurate caloric properties and PρT relations. A viable model to predict two-phase injector flow relations is presented and compared with test data as an example of the usefulness of this equation of state. Show less

This study presents data relevant to the regression rate of various hybrid rocket fuels using nitrous oxide (N20) as the oxidizer, which were obtained using the Stanford Sub-scale Hybrid Test Facility. The fuels investigated include Hydroxyl Terminated Polybutadiene (HTPB), Polymethyl Methacrylate (PMMA), High Density Polyethylene (HDPE), sor- bitol, and paraffin (SP1A). Aluminum in varying concentrations was added to castable grains to observe the effect on regression rate and performance… Show more

This study presents data relevant to the regression rate of various hybrid rocket fuels using nitrous oxide (N20) as the oxidizer, which were obtained using the Stanford Sub-scale Hybrid Test Facility. The fuels investigated include Hydroxyl Terminated Polybutadiene (HTPB), Polymethyl Methacrylate (PMMA), High Density Polyethylene (HDPE), sor- bitol, and paraffin (SP1A). Aluminum in varying concentrations was added to castable grains to observe the effect on regression rate and performance. Multiple injector config- urations were tested to investigate effects on axial variation of port diameter, combustion efficiency, and motor stability. Show less

Recent breakthroughs in hybrid rocket technology centered around the development of a high regression rate, liquifying fuel are overcoming traditional hybrid rocket performance shortcomings. Over the past 8 years research efforts at Stanford University and NASA Ames have identified paraffin wax as a high regression rate fuel and characterized its combustion performance with multiple oxidizers. In order to demonstrate the maturity of paraffin wax technology, an intermediate-scale sounding rocket… Show more

Recent breakthroughs in hybrid rocket technology centered around the development of a high regression rate, liquifying fuel are overcoming traditional hybrid rocket performance shortcomings. Over the past 8 years research efforts at Stanford University and NASA Ames have identified paraffin wax as a high regression rate fuel and characterized its combustion performance with multiple oxidizers. In order to demonstrate the maturity of paraffin wax technology, an intermediate-scale sounding rocket named Peregrine is being built with the objective of reaching an apogee of 100 km. This project, a collaboration between NASA Ames, Stanford University and NASA Wallops will begin with a rigorous ground test program prior to building the flight vehicle. This paper chronicles the design and early build-up of this test facility which is capable of testing 15,000 lb thrust rocket engines. Sources for more information regarding the Peregrine project are also included. Show less

The purpose of this study was to characterize the regression rates of three traditional hybrid rocket fuels along with one novel fuel using nitrous oxide as the oxidizer. In order to complete these tests, a robust test facility was developed for use in this study as well as in future hybrid rocket programs at Stanford University. This stand allowed for rapid successive hot fire testing and the capability to test multiple fuel grain configurations. To date it has been used to conduct 40 hot fire… Show more

The purpose of this study was to characterize the regression rates of three traditional hybrid rocket fuels along with one novel fuel using nitrous oxide as the oxidizer. In order to complete these tests, a robust test facility was developed for use in this study as well as in future hybrid rocket programs at Stanford University. This stand allowed for rapid successive hot fire testing and the capability to test multiple fuel grain configurations. To date it has been used to conduct 40 hot fire tests. Performance values and fuel regression rate data are presented for HTPB, PMMA, HDPE, and sorbitol. Show less