RAeS Lecture: EVTOL Aircraft Preliminary Design & Validation – A Case Study

Why It Matters

By proving a viable, regulation‑compliant electric air‑ambulance design, the project accelerates eVTOL adoption in emergency services and demonstrates the value of university‑industry collaborations in training the next generation of aerospace innovators.

Key Takeaways

• Students designed a tilt‑wing eVTOL air‑ambulance from scratch.
• Design met 60‑minute endurance, 50 NM range, 20% reserve.
• Distributed electric propulsion uses four motors per wing unit.
• Tilt‑wing chosen to avoid rotor downwash during transition.
• Project validated via Simulink models, meeting regulatory CS‑23/25.

Summary

The Royal Aeronautical Society lecture showcased a university‑led case study in which four recent graduates from the University of Birmingham designed an electric vertical‑take‑off and landing (eVTOL) air‑ambulance. The project, part of an integrated master’s group design course, required the team to start from a blank sheet and deliver a fully compliant, emission‑free aircraft capable of rapid urban response.

Using a modified Goodmann design methodology, the students progressed from mission requirements through technology feasibility, concept selection, subsystem integration and a preliminary design review. A tilt‑wing configuration was selected to satisfy a 60‑minute endurance, 50‑nautical‑mile range, 20% battery reserve, and to mitigate rotor downwash during the critical hover‑to‑forward‑flight transition. The distributed electric propulsion system features four parallel motors per main‑wing propeller unit, delivering the required thrust while keeping torque and RPM within safety limits.

Key validation results were demonstrated in Simulink models: the battery state‑of‑charge fell from 100% to about 25%—exceeding the 20% reserve—while thrust, torque and RPM profiles closely matched mission demands. The design also addressed centre‑of‑gravity shifts between hover and cruise by employing a wing‑tilt mechanism and a V‑tail with auxiliary propellers for pitch control. All four students earned first‑class honours and secured industry positions, underscoring the program’s success.

The case study illustrates how academic programmes can produce flight‑ready eVTOL concepts that meet stringent CS‑23/25 regulations, offering a blueprint for future electric air‑ambulance services and accelerating the broader adoption of sustainable urban air mobility solutions.

Original Description

This RAeS Lecture discussed how the potential market for Advanced Air Mobility had given rise to multiple design concepts for Electric Vertical Take-off and Landing vehicles. These aircraft represented unique multi-disciplinary design challenges; capable of both vertical and forward flight, they blended principles from both fixed-wing and rotary-wing aircraft.

To navigate this complexity, a structured and holistic design process was developed. The paper described a comprehensive, phased design methodology to guide the development of novel eVTOL concepts from initial mission requirements to a converged design package ready for the Preliminary Design Review. The methodology was structured in sequential phases, beginning with a rigorous definition of mission requirements and a first-order feasibility analysis. It then proceeded to a core architectural selection process that guided fundamental configuration choices, followed by parallel subsystem embodiment and a critical integration cycle.

This final cycle relied heavily on digital systems modelling and simulation, as well as flight simulation, to verify system performance, validate stability and control, and resolve multi-disciplinary conflicts before committing to detailed design and physical prototypes. To demonstrate its practical application and validate its effectiveness, the methodology was applied to a detailed case study: the conceptual design of “Heli-os,” an eVTOL aircraft configured for an air ambulance Concept of Operations.

The paper followed this case study through each phase, illustrating how the framework’s structured decision and verification points led to a viable and holistic conceptual design. The result was a versatile and grounded methodology that could serve as a roadmap for aerospace engineering students, professional engineers, and designers tasked with eVTOL aircraft design.