Evaluation of CKU-5/A Ejection Seat Catapults under Varied Acceleration Levels.

Post accident investigations of high performance aircraft, such as the F-16 led to the concern about the performance of the ACES II ejection seat catapult CKU-5A loaded by an impressed acceleration. In response to this concern eight catapults were tested using a horizontal deceleration facility in cooperation with the F-16 System Program Office, the Life Support System Program Office, and the Naval Ordnance Station at Indian Head, Maryland. The objective of the tests was to evaluate the performance of the ACES II CKU-5A catapult operating at impressed acceleration levels of 0, 3.5, and 7 G in the Z axis. Analysis of the test results indicates that, although the velocity at separation was not significantly affected, significant delays in time to first motion and time to catapult strip-off occurred. Furthermore, critically high accelerations will be imparted to the ejection seat and crewmember. The Dynamic Response Index modeling technique was used to estimate the probability of injury from the catapult acceleration data. The probability of spinal injury increases from less than 1 at the 0-G level to greater than 99 at the 7-G level.