2019
The starting point of the study was to understand the performance of the widely used APC 13x8 propeller on a specific mini UAV mission. Rather than directly copying the reference propeller, the Tulkas team carried out a reverse-engineering and redesign process examining which geometric features determined thrust, torque and power consumption.
The blade planform, local chord lengths, pitch distribution and profile transitions were transferred into a digital model. The resulting model was used both to evaluate the existing product's behavior and to compare alternative blade profiles under the same boundary conditions.
In the analyses, not just maximum thrust but also the power required to reach the same thrust level was treated as a core performance metric. Taking into account the flow conditions at different radial regions of the propeller, Tulkas developed a new profile distribution. Structural load-carrying capacity at the blade root, efficiency in the mid-region, and loss and noise tendencies at the tip region were all evaluated together.
The new geometry was produced in carbon fiber composite. The composite layup was arranged taking into account the centrifugal and bending loads transferred from the central hub to the blade tip. The goal was not just a lightweight product, but a propeller that maintains its geometry under load, has high stiffness, and can be balanced.
The APC 13x8 reference propeller and the carbon fiber propeller developed by Tulkas were compared on the same thrust test system. RPM, thrust and electrical power data were tracked together during testing. Thanks to repeated measurements at different operating points, the propeller's operating curve was evaluated rather than a single maximum value.
The Tulkas propeller demonstrated approximately 6% higher efficiency than the reference product under in-house static thrust test conditions. This result was evaluated in terms of achieving the same thrust level at lower power, or producing more thrust at the same power level. It was noted as part of the development process that the results belong to the static test setup and that real flight performance must be considered together with the platform, forward speed and mission profile.
The 13x8 study went beyond a single propeller development project for Tulkas. Applying geometry extraction, numerical analysis, composite manufacturing, precision balancing and thrust testing within the same process established a methodology for the propeller family to be developed afterward.
This work demonstrated Tulkas' engineering approach of being able to evaluate an existing product, analyze its performance losses, and develop a more efficient mission-specific alternative. The study was carried out as part of Tulkas' own R&D and comparative product development activity, without claiming any corporate partnership.
You can share your motor data, target thrust, RPM range and mission profile with the Tulkas engineering team for propeller development work specific to your platform.
