Senior Mechanical Design Engineer (ACS Systems)

STEM Boomerang; Rio Rancho (NM); On-site; USD 140,000 - 190,000; Full time

Benefits offered by this job

Meaningful equity

4 weeks paid PTO

Medical plan (100% employee)

Dental & Vision coverage

401k retirement plan

Parental leave

Job summary

Castelion is seeking a Senior Mechanical Design Engineer to design attitude control system hardware for hypersonic strike vehicles. You will develop tanks, valves, thrusters, and integrated assemblies, ensuring reliable propellant storage, flow control, and thrust generation in a fast-paced hardware environment.

You will work with multidisciplinary teams using NX/SolidWorks/ANSYS, applying structural and thermal analyses, and supporting build/test campaigns for flight hardware readiness.

Qualifications

• Bachelor's, Master's, or PhD in Mechanical Engineering or related field
• Experience in aerospace or high-performance fluid/propulsion systems
• Strong background in pressure vessel design and high-pressure integration
• Familiarity with sealing, leak detection, and cleanliness for high-reliability fluid systems
• Proficiency in CAD and analysis tools (NX, SolidWorks, ANSYS)
• Experience with structural and thermal analysis and tolerance stack-up
• Ability to build, test, and troubleshoot hardware in lab/flight environments

Responsibilities

• Design and deliver ACS hardware (tanks, valves, thrusters, assemblies) for long-range hypersonic vehicles
• Collaborate with multidisciplinary teams to enable reliable propellant storage, flow control, and thrust generation
• Analyze and validate hardware through build, test, and integration activities
• Contribute to fast-paced, hardware-driven development with an emphasis on reliability and performance

Skills

Mechanical design

Aerospace propulsion

Fluid systems design

Pressure vessel design

Thermal analysis

Tolerance analysis

Problem solving

Education

Bachelor's/Master's/PhD in Mechanical Engineering

Tools

NX

SolidWorks

ANSYS

Job description

Senior Mechanical Design Engineer (ACS Systems)

Rio Rancho, United States | Posted on 08/06/2026

Castelion was founded to restore America’s ability to field advanced weapons at speed and scale. Inspired by the engineering urgency of the WWII and Apollo eras, we combine rapid iteration, vertical integration, and scalable manufacturing to deliver affordable, high-performance strike systems. Our mission: rebuild industrial agility to strengthen national security and outpace evolving threats.

About the Role:

We are seeking a Senior Mechanical Design Engineer to design and deliver attitude control system (ACS) hardware for Castelion's long-range hypersonic strike vehicles. This role is critical to enabling reliable propellant storage, flow control, and thrust generation for precise vehicle control. You will work hands-on with multidisciplinary engineering teams to design, analyze, build, and validate ACS tanks, valves, thrusters, and integrated assemblies in a fast-paced, hardware-driven environment.

Requirements

• Bachelor's, Master's, or PhD in Mechanical Engineering or related field
  
• 5+ years of experience in mechanical design for aerospace or high-performance fluid/propulsion systems
  
• Strong background in pressure vessel design, fluid systems, and high-pressure component integration
  
• Experience designing tanks, valves, thrusters, or similar propulsion or ACS hardware
  
• Familiarity with sealing methods, leak detection, and cleanliness requirements for high-reliability fluid systems
  
• Proficiency in CAD and analysis tools (e.g., NX, SolidWorks, ANSYS, or equivalent)
  
• Experience with structural analysis, thermal analysis, and tolerance stack-up analysis
  
• Familiarity with high-temperature materials and operation in extreme environments
  
• Experience with hardware build, test, and troubleshooting in a lab or flight hardware environment
  
• Strong problem-solving mindset, thriving in a fast-paced, hardware-rich, high flight cadence environment
  
• Employee Equity: Meaningful equity forall full-time employees - share value has increased 150x in three years
  
• Personal Time Off: Four (4) weeks of paidtime off to unplug, reset, and come back sharp—velocity matters,burnout doesn't
  
• Medical: We offer plans at 100% employeecovered and 80% of dependent coverage
  
• Dental & Vision: We cover 90%employees and 80% for dependents to ensure you and your family haveaccess to quality preventive and ongoing care
  
• FSA/HSA: To support long-term health andfinancial resilience, we offer FSA and HSA options that allowemployees to set aside pre-tax dollars for eligible medical anddependent care expenses
  
• Retirement: 401k plan offered to supportlong term financial growth along side high-impact, high-velocity work
  
• Paid Parental Leave: We support growingfamilies with meaningful time to bond and recover. Birthing parentsare eligible for up to 10 weeks of paid leave, while non-birthingparents may take up to 4 weeks of paid leave. This time can be usedfor pre-natal care, pregnancy, childbirth, and related medicalneeds—ensuring every parent has the support they need during thisimportant life moment.8-weeks of paid parental leave for allparents. Additional paid pregnancy leave for CA employees
  
• Meals & Catering: Frequently cateredlunches and team meals, plus company-covered meals when extra timeor effort is required
  
• Snacks & Beverages: Fully stockedkitchen with unlimited snacks and drinks to keep you fueledthroughout the day
  
• Performance & Fitness: $100 monthlyfitness stipend to support peak performance and health, both insideand outside of work
  
• EV Charging: Onsite electric vehiclecharging available for employees