Due to the growing number of inquiries concerning complete drive units for unmanned aerial systems (UAS), the German manufacturer of 2-stroke and Wankel engines, Sky Power GmbH, has intensified its cooperation with Mejzlik Propeller from the Czech Republic. The objective is the development of propellers coordinated individually to the engine and the customer application.
“In past projects we were approached again and again by our customers for propeller recommendations. Since we develop complete drive units for our customers that are coordinated to the customer application, the requests on the part of the customers were understandable. Since we didn’t want to set up our own propeller development department, we looked around for a partner who had the same understanding of quality as us”, declared Karl Schudt, Managing Partner of Sky Power GmbH, noting the company chose Mejzlik Propeller from the Czech Republic. “We had already worked well together in the past and were convinced of the quality of carbon fiber propellers.”
All Mejzlik propellers are manufactured from carbon fiber and can be adapted in a variety of features, forms and designs of the customer application and the outputs to be achieved, according to the company. Besides the size and the pitch, the number of blades, the weight, the carbon fiber material as well as the surface can also be adapted. “The propeller must perfectly match the engine, as only this way can an efficient utilization of the entire drive unit be ensured”, explained Jan Hruška, Business Development Manager at Mejzlik Propeller.
“Our customers sometimes move sums running into millions in the air, if one counts the UAS and the payload together. Apart from this, in the future flying over groups of people will become routine. Flying must therefore be absolutely safe. For this reason, the quality of the propeller must be given special attention in order to ensure safe flying”, stressed Hruška.
Because of this, the company said various propeller tests are carried out before delivery, including balance tests, an inner structure test, optional RPM tests, and a visual quality inspection is performed.
Apart from that, for Sky Power there was a further incentive for the cooperation. Since every engine is coordinated to the customer specifications, so-called propeller curves are required. “Very few propeller manufacturers can provide these, as the tests are complex”, stated Schudt. The velocity, the flight altitude, the rotational speed as well as the environmental conditions influence the performance of a propeller and consequently also that of the entire propulsion unit. “Based on these details and the computation models, we can calculate and develop the right propeller for every application.”
To design an appropriate propeller, the company also considers the data that it already has from the propellers previously designed and measured. Based on these measurements and their experience, “we can adapt the design to your requirements and give you a basic idea, how the respective propeller behaves”, confirmed Hruška.
Schudt added: “This experience is important for us, in order to provide our customers with a perfectly coordinated drive unit. Because this is what our customers expect”.