Relativity: Terran R avionics ready

Relativity Space says the Terran R rocket’s upper-stage avionics hardware is now ready for hardware-in-the-loop testing, moving flight computers from build work into integrated test. (relativityspace.com) A rocket’s avionics are its onboard electronics: the boxes that handle power, communications, sensors, and flight commands. Hardware-in-the-loop testing connects those real boxes to software and simulated vehicle conditions so engineers can see how the system behaves before flight hardware is installed. (relativityspace.com) Relativity said on April 13, 2026 that all Stage 2 hardware-in-the-loop avionics boxes were ready, while the Stage 1 downcomer had been fully welded and had started acceptance testing. The company also said all internal trays had been installed in the thrust structure and that it had completed a leak check on the outer ring ahead of engine integration. (relativityspace.com) The upper stage is the part of the rocket that finishes the climb to orbit after booster separation. Relativity said the Stage 2 tank’s fuel and liquid-oxygen mechanical assembly was complete, with the liquid-oxygen lid, thrust cone, and headband installed. (relativityspace.com) That work follows an earlier software milestone. In a May 9, 2025 company update, Relativity said it had reached orbit in hardware-out-of-the-loop testing with a full-scale vehicle box count, a step it described as validation ahead of hardware-in-the-loop testing. (relativityspace.com) Terran R is a two-stage reusable rocket that Relativity says will start launching from Launch Complex 16 at Cape Canaveral Space Force Station in late 2026. On its specifications page, the company lists the vehicle at 284 feet tall with 13 Aeon R engines on the first stage and one Aeon V vacuum engine on the second stage. (relativityspace.com) Relativity says Terran R is designed to carry 23,500 kilograms to low Earth orbit with downrange landing, or 33,500 kilograms in an expendable configuration. The company said in March 2025 that it had completed vehicle-level critical design review in December 2024 and had begun first-flight production. (relativityspace.com, relativityspace.com) The company reshaped the program in April 2023, when it retired Terran 1 after a single launch attempt that reached space but not orbit and shifted its focus to Terran R. In that update, Relativity said the new vehicle would prioritize first-stage reusability and target the medium-to-heavy payload market. (relativityspace.com, usatoday.com) The near-term test flow now runs on two tracks: software proving out against real avionics boxes, and structures moving through weld, leak, and acceptance checks. For Relativity, the next visible marker is the same one it has kept on its public schedule: a first Terran R launch from Florida in late 2026. (relativityspace.com, relativityspace.com)