Flight tests have been completed with a "silent" 1.68m (5.5ft)-span propeller that French aerospace research agency Onera refers to as Anibal.

The five-blade propeller was test flown on a Robin DR400-180 R glider towing aircraft in October last year and contributes towards research to reduce general aviation noise. The Anibal's blades are "relatively thin" and the entire propeller is made from "forged carbon", says Onera.

Further research is planned for three- and five-blade propellers and a smaller diameter version for new aircraft fitted with electrical engines.

Onera says Anibal has a noise reduction capacity of 8dB and offers an efficiency comparable to current metal two-blade propellers at an acceptable production cost. The observed aerodynamic performance in glider towing appears "superior to that of the current two-blade propeller", the agency says.

This project was a collaboration between Onera, Duc Propellers, which hopes to market Anibal, French civil aviation authority DGAC and the gliding federation FFVV.

Source: Flight International