Investigation of occupant restraint improvements to the UPCo SIIIS-3 ejection seat

During the Front Line Ejection Equipment Tests (FLEET) program, higher than anticipated radical values were recorded using the 103 Ib Lightest Occupant In Service (LOIS) manikin ejecting in the SIIIS-3 ejection seat with an F-15 forebody. The radical value, an injury potential indicator, is calculated using the seat acceleration in the x and y axes, and the Dynamic Response (DR) in the z mis. It was observed that the LOIS manikin was poorly restrained in the seat regardless of the tension applied to the harness straps. Three concepts have been identified that can be readily incorporated into the seat to improve occupant restraint. These concepts are. an improved seat cushion using a conforming material, inertia reel rollers that are fixed with respect to the headbox, and inflatable elements attached to the lap belt as space fillers. Tests with manikins were performed to evaluate the proposed improvements. The large ADAM (218 Ib) manikin and the LOIS manikin were subjected to impacts along the +z, -x and +y mes using the AFRL Vertical Deceleration Tower (VDT) and Horizontal Impulse Accelerator (HLA). Tests were conducted with the original seat configuration and with the proposed Improvements incorporated into the seat. Manikin response characteristics were measured and results were compared to evaluate the effectiveness of the modifications to the SIIIS ejection seat. Overall, the results for the study were inconclusive. The new seat improved the response of the LOIS manikin in the x and y axes, but degraded the response in the z axis. The new seat showed very little effect on the response of the large ADAM.