Internship Gnc Engineer Jobs in California (NOW HIRING)

Why Castelion, Why Now

Castelion is moving incredibly fast to develop and deliver advanced defense systems at a time when execution matters more than ever. We believe focus and technical excellence are decisive advantages - and we are building a team that can deliver real capability, not just concepts.

This is a rare opportunity to join at an early stage, where your work will directly shape critical systems, influence major technical decisions, and have immediate, real-world impact.

GNC Engineer

As a GNC Engineer at Castelion, you will build the algorithms, models, and software that make our vehicles fly.

You will work across guidance, navigation, flight controls, and high-fidelity simulation to solve difficult problems in high-speed flight. Depending on your strengths and interests, you may focus deeply in one area or work across several. You will take ideas from analysis and simulation through software, hardware testing, and flight.

This role is ideal for engineers who want broad ownership, hard technical problems, and a direct connection between their work and vehicle performance.

Responsibilities

• Develop and tune flight control algorithms for stability and performance across a challenging flight envelope
• Develop guidance algorithms for trajectory shaping and mission execution
• Develop navigation and state estimation algorithms
• Model and analyze actuation systems, including aerodynamic control surfaces and electromechanical actuators
• Build and improve high-fidelity 6-DOF simulations of vehicle flight
• Model vehicle dynamics, aerodynamics, propulsion, sensors, actuators, and environmental effects
• Implement and test GNC algorithms in flight software
• Support Monte Carlo, Software-in-the-Loop (SITL), and Hardware-in-the-Loop (HITL) test environments
• Support vehicle sizing, performance analysis, and hardware requirements
• Support flight test planning, prediction, execution, and post-flight analysis
• Use simulation, hardware, and flight data to improve models and vehicle performance

Basic Qualifications

• Bachelor's degree in Aerospace Engineering, Mechanical Engineering, Electrical Engineering, Computer Engineering, or a related technical field
• Familiarity with aerodynamics, flight dynamics, and rigid-body dynamics
• Strong fundamentals in dynamics, controls, estimation, numerical methods, or simulation
• Strong programming skills in Rust, C/C++, Python, Julia, or a similar language
• Demonstrated ability to solve technical problems through coursework, research, internships, projects, or professional experience
• Ability to communicate technical results clearly and work effectively with multidisciplinary engineering teams

Preferred Skills and Experience

• Experience with flight controls, guidance, navigation, estimation, actuation, or vehicle simulation
• Experience designing or analyzing feedback control systems
• Experience with Kalman filtering, sensor fusion, or inertial navigation
• Experience with trajectory optimization, guidance, or optimal control
• Experience building 6-DOF or other nonlinear dynamic simulations
• Experience modeling or controlling electromechanical or aerospace actuation systems
• Experience with embedded or real-time software
• Experience with Monte Carlo analysis, uncertainty analysis, or model validation
• Experience with SITL or HITL testing
• Experience analyzing test or flight data
• Hands-on experience with rockets, UAVs, robotics, Formula SAE, research vehicles, or other complex hardware systems

Other Duties

Please note this job description is not designed to cover or contain a comprehensive listing of activities, duties or responsibilities that are required of the employee for this job. Duties, responsibilities and activities may change at any time with or without notice.

Benefits And Perks

All full-time employees are granted meaningful long-term equity, sharing in the company's significant growth trajectory. We offer four (4) weeks of paid time off, ten (10) company-paid holidays, and comprehensive health benefits - including 100% employee-covered medical and strong dependent coverage, along with dental and vision plans. We also provide paid parental leave to support growing families, a $100 monthly fitness stipend to promote health and performance, and onsite EV charging for convenience. In addition, employees enjoy perks like catered meals, company-covered food during high-demand periods, and a fully stocked kitchen to stay fueled throughout the day.

While this position does not currently require a U.S government-issued security clearance, it may in the near future. Therefore, the ability to obtain and maintain a U.S. government–issued security clearance is required. U.S. citizenship is required, as only U.S. citizens are eligible for a security clearance.

Affirmative Action/EEO Statement

Employment with Castelion is governed on the basis of competence and qualifications and will not be influenced in any manner by race, color, religion, gender, national origin/ethnicity, veteran status, disability status, age, sexual orientation, gender identity, marital status, mental or physical disability or any other legally protected status.