Changelog

Notable changes to oApogee, hardware, firmware, and documentation together.

Errata are safety information. When hardware and firmware ship, a change to a detection threshold or a known defect in a board revision appears here, because somebody flying the previous version needs a way to find that out.

Dates are ISO. Versions follow the repository's VERSION file.

Unreleased

Added

• Two format specifications, published so third parties can write their own tools. docs/spec/telemetry-packet.md fixes the downlink wire format at version 1; docs/spec/log-format.md fixes the onboard log at version 1. Both carry a reference implementation and conformance rules.
• Structured source for the bill of materials, tiers, glossary, flight state machine, preflight checklist, troubleshooting index, system diagram, and the flight log submission format.
• The system block diagram, generated from data/system.yaml rather than drawn, with a build check that fails when the committed SVG stops matching the data.
• Content pages: start here, build guide, firmware and flashing, mounting, ground station, reading your data, safety and rules, reference, FAQ, about and license.
• Build checks: prose rules, data cross-references, internal links and anchors, the verification marker index, and the schematic.

Decided

• No microSD socket. Card sockets unseat under boost, and the failure mode is the worst available: the flight proceeds normally and the data is gone. Storage is soldered-down QSPI flash with LittleFS.

• Passive instrumentation only. No ejection charge control, no deployment control, no igniters, no pyrotechnics, at any tier, ever. The boundary keeps the worst outcome of any bug in this project a disappointing graph.

• Raw and derived values are both logged. Twelve of thirty-six bytes per record, spent so the payload's own work can be audited and so old flights can be reprocessed with a better filter.

• No encryption on the downlink, so the link stays legal to transmit under amateur radio rules. Compact binary is efficiency; scrambling would be obfuscation.

• Two build paths. Modules, on breakout boards, buildable before a PCB exists. Board, the custom PCB, once fabricated. The tier owns the capability content and the path owns only the assembly content.

• Licensing. CERN-OHL-S 2.0 for hardware, Apache 2.0 for firmware and software, CC BY-SA 4.0 for documentation. Reciprocal on the board because the plausible bad outcome is a closed volume clone and -S at least requires that improvements come back; permissive on the firmware because that is the part worth having other people embed everywhere, with Apache over MIT for the express patent grant. The documentation gets share-alike, accepting that a competitor may reproduce the build guide commercially with attribution.

• Trademark policy. The design is open, the name is not. Licences do not stop a clone shipping under this name; a trademark does.

Not yet decided

• Whether the high-g accelerometer belongs at Link and above, or as an option at every tier driven by motor class. These and the rest are argued out in docs/open-questions.md.
• Whether the ground station display uses WebSerial, which excludes iOS entirely.
• Complementary filter or Kalman filter for the sensor fusion.

Status

Nothing has been fabricated, assembled, weighed, priced, or flown. Every cost, mass, range and endurance figure on the site is absent rather than estimated, and each gap records what evidence would close it. The full list is at oapogee.space/status, read from the content files at build time so it cannot go stale.