Full Time Engineering Jobs in Walnut, CA (NOW HIRING)

About Castelion

Castelion is redefining defense development through rapid iteration, aggressive testing, and modern commercial manufacturing at scale. We design, build, and test next-generation long-range strike weapon systems to give the United States and its Allies a decisive advantage and deter future conflicts.

Role Overview

The Manager, Propulsion Engineering, plays a central role in delivering high-performance rocket motor systems at speed and scale. This position combines deep technical expertise in solid propulsion with strong engineering leadership, guiding a team responsible for the design, development, and production of solid rocket motor systems and key propulsion components.

This leader owns both technical direction and team execution, ensuring designs are robust, manufacturable, cost-effective, and aligned with aggressive program timelines. The role requires someone who can operate decisively in a fast-paced, resource-constrained environment while building a high-performing engineering culture.

Responsibilities

Technical Leadership & Ownership

• Lead the design and development of solid rocket motor primary and secondary structures, propulsion components, and interfaces.
• Drive motor design and propellant-related decisions, ensuring performance, safety, manufacturability, and cost targets are met.
• Translate program objectives into scalable, production-ready designs aligned with speed and affordability goals.
• Oversee CAD models and drawings, ensuring compliance with internal standards and ASME Y14.5 GD&T practices.
• Guide rapid iteration cycles, validating designs through testing and enabling fast design evolution.
• Provide technical authority for hardware discrepancies, failure investigations, and corrective actions.
• Partner with supply chain to mitigate risks and adapt designs for material availability and production constraints.

Engineering Management & Team Leadership

• Build, lead, and scale a high-performing propulsion engineering team.
• Establish and reinforce a strong engineering culture focused on ownership, accountability, and execution.
• Mentor engineers across experience levels, fostering both technical depth and independent decision-making.
• Ensure the team delivers high-quality work on aggressive timelines with clarity of priorities and accountability.
• Act as the go-to decision-maker, providing clear direction when teams ask: How should we do this?

Cross-Functional & External Engagement

• Communicate effectively with customers, leadership, and cross-functional teams.
• Navigate and collaborate with government stakeholders and program partners.
• Ask tactful but critical questions to uncover risks, challenge assumptions, and improve outcomes.
• Support program reviews, technical briefings, and milestone readiness.

Hands-On Execution

• Stay close to the hardware by supporting assembly, integration, testing, and troubleshooting.
• Provide expert guidance during prototype builds and production ramp-up.
• Lead or contribute to trade studies and system-level decisions, often with incomplete data.

Basic Qualifications

• Bachelor's degree (or higher) in aerospace, mechanical, materials, manufacturing engineering, physics, or related field.
• 7+ years of experience in propulsion, mechanical systems, or fluids design, analysis, or testing.
• Demonstrated experience in rocket motors or propulsion systems.
• Proven ability to lead projects or small teams in a technical environment.
• Strong communication skills across technical and non-technical audiences.

Preferred Skills and Experience

• Deep expertise in solid propulsion, including:
• Motor design
• Propellant formulation and behavior
• Experience with liquid propulsion systems (as a complement to a strong overall propulsion background).
• Hands-on experience with rapid product development and high-rate manufacturing.
• Proficiency in CAD tools (NX, Creo, CATIA) and GD&T per ASME standards.
• Experience with aerospace materials (metals, composites, plastics).
• Familiarity with insensitive munitions standards and practices.
• Active DoD Secret Clearance or ability to obtain one.

Additional Requirements

• Willingness to support extended hours or weekend work during critical integration, test, and flight milestones.

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.