GNC Engineer

Hop Aero is a venture-backed startup building rockets that deliver cargo anywhere on Earth in minutes. Our mission is to enable resilient global logistics to protect and improve our way of life. Our founding team has prior experience founding a satellite startup and taking it to orbit, launching 20+ Falcon 9 missions at SpaceX, and leading engineering teams at some of the world’s most advanced aerospace organizations. The company is well-capitalized through venture funding and government contracts. **About the role** We’re hiring a GNC Engineer to own guidance, navigation, control (GNC), and flight-dynamics development for Hop Aero’s reusable rocket cargo vehicles. This is a foundational technical role. You will build the models, simulations, algorithms, and test infrastructure that take our vehicles from the pad through ascent, coast, re-entry, and precision propulsive landing. We are looking for someone with deep intuition for flight dynamics and control of real vehicles, not just someone who can build simulations in isolation. You should be comfortable moving between first-principles modeling, Monte Carlo analysis, controller design, actuator and sensor limitations, software implementation, HIL testing, and flight-test data. You will have significant ownership over vehicle behavior. The models you build will directly inform vehicle architecture, actuator sizing, sensor selection, flight software, test planning, and ultimately whether the vehicle flies. **Job Description** - Serve as the responsible engineer for guidance, navigation, control, and flight dynamics - Build and maintain high-fidelity 6-DoF vehicle simulations from first principles - Model vehicle aerodynamics, propulsion, mass properties, sensors, actuators, winds, disturbances, and uncertainties - Develop guidance and control algorithms for ascent, coast, attitude reorientation, powered descent, and vertical landing - Select and implement appropriate control architectures including PID, LQR, MPC, gain scheduling, or other methods where appropriate - Develop navigation and state-estimation systems using inertial, GNSS, vision, radar, altimetry, and other sensing modalities - Perform Monte Carlo analysis and define vehicle dispersions, stability margins, and control authority requirements - Translate simulation results into requirements for propulsion, TVC, RCS, avionics, structures, and vehicle configuration - Integrate GNC algorithms with flight software and embedded systems - Develop SIL and HIL environments to validate flight software and vehicle behavior prior to test - Support tethered tests, hover tests, hop tests, and full flight-test campaigns - Analyze flight data, identify model discrepancies, and continuously improve simulation fidelity - Own GNC technical risks through design reviews, test-readiness reviews, and flight-readiness reviews - Work in person with the team at our shop in Orange, CA **Requirements** - 5-10 years of relevant experience in GNC, flight dynamics, controls, or closely related fields - Deep understanding of rigid-body dynamics, flight mechanics, guidance, controls, and state estimation - Demonstrated experience building and using high-fidelity 6-DoF simulations - Experience developing control systems for real flight vehicles - Strong understanding of actuator dynamics, sensor limitations, latency, uncertainty, and real-world nonlinearities - Experience with MATLAB/Simulink and Python and/or C++ - Ability to translate simulation and analysis into real vehicle requirements and design decisions - Experience validating models and algorithms against hardware or flight-test data - Ability to work directly with propulsion, avionics, flight software, structures, and test teams - Willingness to participate directly in vehicle integration and flight-test operations - **Must be a US Person under ITAR - _Hop Aero will not sponsor visas for this role._** **Nice to have** - Experience with vertical takeoff and landing vehicles, launch vehicles, missiles, high-speed aircraft, or spacecraft - Experience taking a vehicle from first simulation through hover or flight test - Experience with thrust-vector control, reaction-control systems, or powered descent - Experience with terrain-relative navigation, machine vision, or GPS-denied navigation - Experience designing or operating SIL and HIL test environments - Experience with Monte Carlo dispersion analysis and flight-envelope expansion - Experience on DoD or U.S. Air Force flight programs - Prior experience at a fast-moving aerospace or hardware startup **What we offer** - Competitive salary and meaningful stock options - Healthcare, office meals & snacks - Direct collaboration with founders & engineers with rich flight heritage - Significant technical ownership from day one - The opportunity to define the GNC architecture of a new class of flight vehicle - Fast upward mobility as the company grows **Even if you don’t meet every single requirement, we’d still love to hear from you. Greatness looks different in every one of us - and we need the best tackling this problem.** Visa sponsorship is not available for this role.