UNRETARDED MODE.- In the unretarded mode of delivery, the weapon is released from the aircraft, and the fins remain in the closed position. The weapon free falls to the target. In the unretarded mode of delivery (without pilot option), the cotter/ safety pin installed in the fin release band is not removed or replaced with an arming wire. However, the safety tag that reads REMOVE BEFORE FLIGHT is removed.

IN-FLIGHT SELECTION.- The most frequently used mode for delivery is the in-flight selection (pilot option) mode. The pilot can drop the weapon in the retarded or unretarded mode. This is possible by connecting the swivel loop of the fin release arming wire to the tail arming solenoid of the bomb rack. If the pilot energizes the arming solenoid upon weapon release, the arming wire remains connected to the arming solenoid and is pulled from the fin release band at weapon release, which allows the fins to pop open and results in a retarded delivery. If the pilot does not energize the arming solenoid upon weapon release, the arming wire is pulled free of the arming solenoid. This allows it to remain in the fin release band, preventing the fins from opening, which results in an unretarded delivery.

BSU-85/B Air Inflatable Retarder

The BSU-85/B bomb fin attaches to the Mk 83 general-purpose bomb. It is an air-inflatable retarder designed for very low altitudes. It can be dropped in either high-drag (retarded) or low-drag (unretarded) mode (fig. 1-30). The BSU-85/B fin

Figure 1-30.-Typica1 BSU-85/B air-inflatable retardable fin with high and low drag configurations.

(fig. 1-31) attaches to the bomb body by eight setscrews. _{and B). The four fixed fins provide low-drag} It is a self-contained unit that consists of a stabilizer _{aerodynamic stability. The wedges installed on the}

^{assembly (canister housing) with four fixed fins} trailing edges provide stabilizing spin during a low-drag (X-shaped) and a lanyard assembly (fig. 1-31, views A release. When stored in its original shipping/storage

Figure 1-31.-BSU-85/B air-inflatable retarded fin (top and rear view).

container, its shelf life is 10 years. Its service life is 1 year when exposed to adverse environmental conditions, but it maybe extended by visual inspection at 1-year intervals.