I would like to offer our propellers are produced in Ukraine. We improve them for 20 years and achieved some success. Sabre propeller works fine in the whirlwind of the pushing motor aircraft X-32 and X-34. German plane CT-SW with a propeller diameter of 1700 mm and an engine Rotax-912-80 easy to reach speeds of 250 km/h, even without installing the meter. He showed a good performance on other planes: Sigma-4, the VIS, the T-10, the sky Arrow. Installation screw diameter of 1600 mm for engines Rotax-503 gave increased traction on 25-29 kg. The diameter of propeller 1750 mm is the most popular for the Rotax-912-100. Sabre Propeller diameter 1840 mm has proved to Savage plane. I am sure that you are using different propellers. But your plane with our propellers will fly even better.