The overriding objective of this project is to promote a system level understanding of autonomous control systems in aerial vehicles, using innovative and deductive reasoning. Phase one includes knowledge acquisition for the helicopter dynamics, and the ordering of vehicle, sensors, and electronics. In addition to the design of Fuzzy rules, phase two will require several helicopter dynamic tests using sensors and other electronic components. The data will be processed and analyzed in order to determine the final adjustments to the system. The final project objective is to demonstrate a fully autonomous takeoff, hover, and landing of the aircraft. In addition to the demonstration flight of the aircraft, research and validation studies will be conducted for the potential certification of a scale civil remotely operated aircraft.
These are actually two separate, yet intertwined projects. There are many scientific instruments ineligible to fly on balloons because they are too heavy. If parasitic mass can be reduced overall in balloon support systems, this mass savings can be converted to additional payload capacity that can be dedicated to larger and more complex (heavier) scientific instruments. SCE students are engaged in an intensive component-by-component study of the entire balloon support system to identify areas where mass can be reduced. Students are investigating advanced material technology and performing computer-aided stress analysis to identify concepts to reduce mass without negatively impacting balloon reliability.
Some parasitic mass in balloon support systems is necessary to provide sufficient structure to withstand the severe shock events associated with release of the payload from the balloon and parachute deployment necessary to gently return the payload to Earth at the end of a flight. These events have been shown to be quite violent and evidence suggests that payload damage occurs during these events. SCE students are simultaneously investigating a dozen or more specific designs and operational methods that might be employed to mitigate these shock events, reduce or eliminate payload damage and result in mass savings for structure no longer needed to withstand these events.
Accurate measurement of atmospheric parameters (primarily temperature) at and below balloon float altitudes (~120,000 feet) has long been desirable to NASA. In addition to thermal implications, knowledge about the atmosphere profile can provide operations personnel with decision-influencing information. The difficulty in measuring atmospheric properties at these altitudes is the extremely low density, about one half of one percent of the density on the Earth's surface. SCE students are designing a low-mass, low-conductance temperature sensor and associated circuitry that can collect and transmit the data via Iridium to a ground station. The students are also designing a balloon-mounted delivery system that maximizes the molecular interaction between the atmosphere and the temperature sensor to produce a high accuracy measurement. They are creating and utilizing Computational Fluid Dynamics (CFD) models to predict the airflow over and through the instrument. Once designed and fabricated, the system is expected to be test flown on a balloon.
At balloon float altitudes, many scientific instruments will not function properly in the near vacuum conditions. For these cases, a pressure vessel is required that can provide both a pressurized operating environment as well as assist in thermal control. The two current approaches to these large pressure vessels are metal or composite structures. Traditional spun metal pressure vessels are prohibitively heavy and advanced composite structures can be extremely expensive. The NASA balloon program has been developing materials technology that can be used to produce lightweight and low-cost pressure vessels. SCE students, working with Aerostar International, Inc., are utilizing this technology to design, fabricate and test a lightweight and low-cost pressure vessel that will allow more vacuum-sensitive scientific instruments low cost access to near space.
NASA's Columbia Scientific Balloon Facility (CSBF) currently utilizes 'stacks' for controlling various functions of long-duration balloons such as relaying scientific data to the ground and control operations of the balloon itself. These stacks have significant responsibility toward the success of the mission. The goal of this SCE student project is to integrate a Peripheral Interface Controller (PIC) onto the Housekeeping, Power Supply and Command stacks. The purpose of each PIC is to move the supporting features of existing chips onto the PIC and thereby reducing the amount of supporting hardware on the stack. By eliminating support hardware, power consumption will also be reduced. The integration is transparent in that the stack's current functionality is not affected. However, since each of the three stacks has a unique function and design, unique PIC microcontrollers will be selected for each stack. To make an educated choice of a PIC, each stack is assessed for its individual design parameters.
CSBF desires to upgrade the design of their charge controller module (CCM) on their long duration balloon (LDB) payloads to enable them to be directly interfaced by RS232 serial communications without an external electronics stack. SCE student design involves a board that will interface with the 3 existing boards in the CCM to receive telemetry from and send commands to those boards, and interface with the main computer through serial communication. This project includes background and planning phases, a preliminary design phase, and final design phase. The background and planning phase involves parts analysis the project proposal. The preliminary design phase involves designing the circuit, writing software, a preliminary design review, acquiring parts, bread boarding and testing the circuit. The final design phase involves designing the printed circuit board, updating the software, critical design review, final assembly, and final testing.
NASA desired a characterization of the flow coefficient for its modified EV-13 scientific balloon valve over an appropriate range of Reynolds numbers. This flow coefficient is used in a balloon flight computer model to predict helium discharge rates at various flight altitudes and differential pressures across the balloon envelope. This helps balloon operations personnel determine helium vent durations to attain a particular altitude changes. SCE students designed and fabricated an open atmospheric air flow system to provide a steady and continuous air flow source. Given the ambient conditions, the pressure drop across the valve and the measured velocity profile, the students used Ramskill's equation to determine the valve flow coefficient over a range of Reynolds numbers. When compared to previously published results, the students' test results compared well and reinforced previous estimates. The students also performed a detailed error/uncertainty analysis to quantify the uncertainty in the results they obtained. SCE students also designed and fabricated a water channel test setup to again determine the discharge coefficient using water as the working fluid. These results compared well to the results found using air. The water channel also enabled results to be obtained over a wider range of Reynold's numbers. The students also created a CFD model of the helium valve to not only reproduce the results found with air and water as working fluids, but also predict how the valve will perform with helium as the working fluid at high altitudes.
Balloon reliability has been an issue since high-altitude, long-duration balloons were first flown. Zero-pressure polyethylene balloons are large complex systems and their reliability is a complex issue involving multiple variables. SCE students statistically analyzed the reliability data for hundreds of flights flown by the Columbia Scientific Balloon Facility with respect to several variables including manufacturer, volume, number of caps, launch stress index, and flight duration. This analysis helps determine if certain factors can be used as general predictors of reliability for balloon designs.
- Advanced Thermal Control Technology Test Bed
- Non-Solar Power Systems Research and Design
- Power Beaming Demonstrator
- Remote Coltrollable Landing System
- Water Channel Project
- High Altitude Station Keeping Balloon
- Global Realtime Access of Balloon
- Balloon Payload Floatation and Protection
- Top of the Atmosphere Radiant Flux Database