RIO : Avionics Box Mass Reduction
Internship with the Remote In/Out (RIO) Group at SpaceX
Summer 2015
During the Summer of 2015, I interned in SpaceX's Remote In/Out (RIO) Group, led by Craig Remillard. Craig brought me on as the group's only mechanical intern to investigate novel approaches to reducing the mass and volume of the enclosures that house and protect avionics during flight. Ultimately, I designed a prototype of a smaller and lighter low-contact-count connector and performed proof-of-concept testing.
A COMPLICATED WIRE HARNESS VISIBLE INSIDE FALCON 9 INTERSTAGE
I spent the first part of my internship on a trade study of several concepts for reducing the mass and volume of avionics enclosures, such as venting to reduce pressure loading, switching to plastic or composite structures, alternate methods for environmentally sealing, and switching to different electrical connectors. The outcome of the trade study, coupled with my colleagues' insight on the difficulties of fabricating and debugging complicated wire harnesses, led me to spend the rest of my internship investigating alternative connectors.
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Commercial aerospace connectors are bulky and have poor pin-density in two- and four-contact configurations - configurations commonly used to interface to valves and sensors. Connectors must survive vibrational, shock, and thermal environments at vehicle QTP levels; additional design requirements include water resistance, EMI shielding, a secondary retention mechanism, and easy installation. After a survey of COTS options showed that SpaceX was already using some of the best connectors available, I started work on the conceptual design of a new connector.
VIBE TESTING PROTOTYPE CONNECTORS ON THE "RHINO"
WATER INGRESS TESTING ON PROTOTYPE CONNECTOR SOCKET
I chose to design a coaxial connector based on a headphone jack because the two- and four-contact configurations have the same OD, allowing standardization of the plug and socket shells. I focused on the connector shell mechanical design, investigating alternative socket-enclosure mounting and secondary-retention methods that minimized connector diameter while maintaining manufacturability. The connector's right-angle configuration improves harness strain relief and allows for thinner and lighter enclosures.
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I performed vibrational and thermal proof-of-concept tests on prototype connectors, and developed the first testing procedure for water resistance in SpaceX’s avionics department to test my concept for mounting the connector sockets to the enclosures. My design for the connector would reduce both the mass and the OD to half that of the currently used connectors. While further development of the connector was halted after my departure (too costly and sufficiently low-priority), my PDR was well received and prompted some interesting conversations that I hope led to a more comprehensive understanding of just how intertwined the challenges facing the avionics hardware team are.
Photo Credit
Elon Musk's Billion-Dollar Crusade to Stop the A.I. Apocalypse. Maureen Dowd. Vanity Fair, March 2017.