Mejzlik Propellers collaborated with Hirth Engines to identify a propeller solution optimized for use with Hirth’s 4202 engine. Hirth, a manufacturer of two-stroke engines, required a propulsion setup specifically suited to forward flight applications rather than general compatibility.
In response, Mejzlik provided a comprehensive propulsion configuration as part of its Professional Propulsion Systems (PPS) initiative.
This program delivers propulsion solutions optimized across engine, propeller, and mission requirements, aligning with Hirth’s goal of developing a reliable, European-manufactured propulsion system for forward-flight use cases.
Project Initiation
The project began in February 2024, following a request from Hirth to identify a propeller tailored for forward flight, distinct from the vertical lift demands typical of multirotor drones.
The two companies established a shared technical framework early in the collaboration. Mejzlik contributed expertise not only in the design and manufacture of carbon fiber propellers but also in system-level integration. The PPS methodology applies iterative, data-driven analysis to optimize performance across the entire propulsion system.
Rather than proposing an existing product, Mejzlik evaluated Hirth’s performance requirements, reviewed available propeller configurations, and conducted simulations using actual engine data. A primary objective was to match the engine’s power curve with the aerodynamic characteristics of the propeller to maintain optimal performance across the full flight envelope.
Technical Development
In contrast to common practices in UAV development—where propulsion elements are selected in isolation—Mejzlik applied a top-down methodology, considering the propulsion system as a unified whole. This approach is based on principles from traditional aerospace engineering, where subsystems are developed in alignment with overall system objectives.
Engineering efforts focused on expected cruise conditions and emphasized consistent power delivery, reliable thrust output, and ease of integration over theoretical maximum efficiency.
Candidate propellers were selected based on their compatibility with the 4202 engine and the specified operational profile. Models evaluated included the Mejzlik 28.5×12 3B, 29×10 2B EVO, 30×12 2B, and 32×10 2B. The evaluation process consisted of:
- Simulation and performance modeling across a wide range of RPM values and flight velocities.
- Analysis of thrust characteristics, torque behavior, mechanical power output, and system-level propulsion efficiency.
- Generation of a comprehensive performance datasheet – a standard deliverable within the PPS process – allowing for precise system integration, flight planning, and performance forecasting.
This data-driven process allowed for the delivery of a propulsion configuration tailored to specific operational requirements, reducing the need for iterative testing and enabling more predictable performance. The resulting configuration also provides a technical reference for similar future applications.
Application Context & System Benefits
The validated configuration enabled Hirth to advance development activities without the trial-and-error typically associated with propulsion matching. Although the appropriate propeller was identified from Mejzlik’s existing PPS portfolio, the company regularly supports custom solutions—particularly in UAV and defense applications where unique aerodynamic and structural parameters must be addressed.
While the integration data for this project has been made available, similar projects often involve restricted information due to application sensitivity. For this reason, the PPS process emphasizes structured documentation and validated performance to support system integration, even in the absence of full disclosure.
Future Outlook
The collaboration between Mejzlik and Hirth is expected to continue. With Hirth’s broader engine lineup, further PPS configurations can be developed for a range of aircraft types, including VTOL systems and hybrid propulsion architectures.
Ongoing projects are expected to reduce development time, improve system validation, and enhance the consistency and reliability of propulsion solutions.
This collaboration demonstrates the intended function of the PPS initiative: to provide propulsion configurations that are technically validated, operationally aligned, and developed through structured engineering processes.
