File:Photo of the head nozzle unit of the flying firefighting robot.jpg

English: "We conducted a water leakage test. In the test, each case rotates the shaft for 30 min inside a water depth of 50 mm. The experimental results showed that no shaft leakage was observed in any of the three proposed waterproofing methods. We decided to select the B3 case for installation based on the advantage of reducing the shaft length. Based on the shaft structure of B3, we designed a U-shaped connecting instrument (Figure 5C), which could transmit torque to the shaft through the squared convex cube. This U-shaped instrument can cover the swivel joints (Figure 5E) as Figure 6. The details are explained in Section 5.3.4."