Experimental investigations on high altitude airship propellers with blade planform variations

Wind tunnel tests of five propellers with different blade tip widths are carried at pitch angles between 20.5 degrees and 40 degrees. The aerodynamic performance are provided, which can be treated as a supplement of the high altitude airship propeller database. The influences of the blade planform and advance ratio on both power coefficient and propulsive efficiency are analyzed. It is found that at advance ratio below 0.8, the propeller with narrow tip has higher efficiency but limited power coefficient. While at advance ratio above 0.8, the propeller with wider tip has the advantages of higher power coefficient and acceptable efficiency. The variation of the propulsive efficiency with planform and advance ratio is dominated by the radial distributions of the airflow angle and interference angle.