1 Subjects: “...controllable pitch propeller...”

2 Subjects: “...propellers...”

3 Subjects: “...propeller wake...”

4 Subjects: “...propeller...”

5 Subjects: “..."green" propellants...”

6 Subjects: “...solid propellant blasting...”

7 Subjects: “...propeller...”

8 Subjects: “...propeller...”

9 Subjects: “...rocket propellant...”