Senior Mechanical Design Engineer 6 months initial (Inside IR35) – 4 days p/week on site (Buckinghamshire) Copello is recruiting for a Senior Mechanical Design Engineer to join our clients Avionics Business Unit. You will be supporting a portfolio of aerospace products for both military and civilian applications. Key Responsibilities • Lead mechanical design activities for new product developments. • Produce detailed designs using 3D CAD (SolidWorks preferred), and simulate mechanical behaviour using FEA and CFD tools. • Prepare technical estimates for non-recurring costs and manpower. • Manage technical aspects of external suppliers and outsource providers. • Liaise with internal and external stakeholders, including customers. • Conduct tolerance analysis including Geometric Dimensioning and Tolerance. • Act as Project Engineer when required, supporting bids and development. • Coach and mentor junior mechanical engineers. • Generate and amend drawings and documentation to BS8888 standards. • Support continuous improvement initiatives across processes and tools. Skills & Experience • Strong background in aerospace or defence mechanical design. • Proven expertise in 3D CAD (SolidWorks advantageous). • Experience with FEA and CFD simulation tools. • Familiarity with engineering lifecycle from concept to delivery. • Knowledge of materials, finishes, and environmental implications. • Understanding of composite design and production techniques. • Experience in regulated industries such as aerospace, automotive, or medical. • Chartered Engineer status (or working towards). • Excellent communication and documentation skills. • Requirements management experience. Key Measures • Demonstrated experience across full engineering product lifecycle. • Ability to author, review, and approve engineering drawings to BS8888 and ISO standards. • Strong grasp of structural analysis and thermal CFD. • Ability to work independently and lead project teams. • Commitment to sustainability and product support. Security Clearance Role will require candidates to have active SC clearance or eligibility for SC