Barring the smallest manned airplanes, most aircraft that are pulled around by a prop have variable pitch propellers. The reason for this is simple efficiency. Internal combustion engines are most ...

Presentation of the DNV GL certificate by Dr. Olaf Richter (right) in the presence of his inspector, Dieter Ekat (2nd from left) who supported the test series, to Piening boss Mathias Pein (2nd from ...