Research Article
Design Method for Contra-Rotating Propellers for High-Speed Crafts: Revising the Original Lerbs Theory in a Modern Perspective
| ā | Case B-1 | Case B-2 | Case B-3 |
| Front number of blades | 4 | 5 | 4 | Aft number of blades | 4 | 5 | 4 | Front EAR | 0.84 | 0.93 | 0.84 | Aft EAR | 0.97 | 1.07 | 0.97 | Strength margin | 5 | 5 | 5 | Cavitation margin fore | 0.78 | 0.78 | 0.78 | Cavitation margin Aft | 0.7 | 0.7 | 0.7 | Unloading curve | Y | Y | N | Propeller efficiency | 0.648 | 0.646 | 0.650 |
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