Browsing by Author "Rorabeck, Casey"

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Benefits of Modular Ball Valves in Thermal Control Systems
(2024 International Conference on Environmnetal Systems, 2024-07-21) Rorabeck, Casey; Schwieso, Patrick; Schlutt, Mark; Marandola, Elizabeth
Ball valves offer numerous benefits in thermal control system applications. Straightforward to design and consisting of few parts, ball valves can be more compact than other styles of valves, saving mass and volume. Reconfigurable for specific functions, a ball valve can provide proportional control and/or isolation. The valve seats allow robust sealing for internal leakage while maintaining a low actuation torque, allowing ball valves to be actuated in many ways, including the ability to turn by hand for manual override functionality without needing extra gearing or long lever arms. Ball valves also have a comparatively low-pressure loss, especially in the fully open position, which benefits the often-limited pressure loss budget of a spacecraft thermal control system. Ball valve components require less restrictive tolerances and are mostly axisymmetric making them readily manufacturable. Ball valves have proven quite durable, handling the loads during the launch and descent of spacecraft. The general methodology for designing ball valves is also consistent across a large range of sizes. In addition to all the performance benefits, the modularity of ball valves to perform different tasks can reduce nonrecurring engineering cost of a system. Due to this cost reduction and adequate performance characteristics, Sierra Space is developing a line of modular ball valves. These valves, evolving from previously qualified Sierra Space ball valves, can proportionally control, isolate, and divert flow. This paper will discuss the advantages of ball valves in spacecraft thermal control systems and detail the development of Sierra Space's line of modular ball valves.
Flexible Motor Controller Architecture for Spacecraft Applications
(2024 International Conference on Environmnetal Systems, 2024-07-21) Myers, Connor; Wallace, Russell; Cowgill, Bradley; Rorabeck, Casey; Tarver, Elias; Carney, David; Moffatt, Sam; Bourget, Mike; Heindl, George
Brushless DC (BLDC) motors are ubiquitous to spacecraft operation. BLDC Motors provide the driving force for many different components within ECLSS and TCS such as: valves, fans, blowers, pumps, and rotary separators. Specific to valve operation, several considerations come into play when developing a control system for a BLDC motor. Position sensing/indication, mass, power, volume, cost, radiation susceptibility, and maintainability are among primary design driving factors for developing a BLDC motor controller. Looking at the potential needs for valve control and design, a common product was developed to balance the design driving factors towards the end goal of cost reduction and simplifying on-orbit logistics and maintenance for future spacecraft. The flexible design supports a wide array of valve functions and can be maintained/removed without exposing the internal fluid to the spacecraft environment. The microcontroller-based design provides a simplified and abstracted serial data interface to the flight computer, enables low level hardware and software fault detection, allows modularity for adding additional application specific sensors and features without impacting vehicle avionics, simplifies channelization and wire harness to vehicle avionics, and allows for in field software updates. The design supports different part grades from automotive to grade 1 to optimize for the application. Additionally, key internal components have been tested to support the radiation and vibration environment encompassing many potential valve applications.