One Way Initiators weigh an average of 0.12 pounds with a length of 2.25-3.00 inches and diameter or hex of 0.75-inch. The JAS-39 One Way Initiator was qualified by similarity, reference document QTP816422. The B-1B and F-15 version was qualified to L320C2005. PacSci EMC’s One-Way Initiator designs are shown in the photos below.
An example of how One-Way Initiators can assist in sequencing the system follows (see Figure 32). Assume an aircraft with a forward and aft canopy, a system with canopy jettison system containing an internal Arm Fire Initiator (AFIs) in each cockpit and two external AFIs. The design is to allow functioning of either external AFI jettisons both canopies but the internal AFI in one cockpit can only jettison the canopy for that cockpit. The addition of One-Way Initiators allows this type of functionality within a system.
The operation of the unit is based on the high energy output (detonating) from the input ETL activating a firing pin that initiates a percussion primer. The primer then fires a transfer charge with a detonation output sufficient to fire the attached ETL on the other end. Since the firing pin and primer can only function in one direction, the one-way operating device is achieved by orientation of the internal components. The same is true for an inert one-way initiator except the percussion primer integrated into the end fitting an attached RDCTL. PacSci EMC’s inert design is similar to explosive loaded version except there is no transfer charge as the units above. Also the firing pin’s outer diameter is more than the inside diameter of the HE adapter. Additionally, the percussion primer does not emit enough force to drive the firing pin into the HE end fitting of an attached ETL HE end fitting.