Final answer:
While the ACES II ejection system's maximum operation speed in knots is not specified, the context of the question implies high-speed ejection tests were conducted at speeds of 1000 km/h and rocket sleds have reached speeds of 10,000 km/h. The U.S. Air Force estimates that humans can survive 10 gs of acceleration.
Step-by-step explanation:
The ACES II is an advanced ejection seat system used in modern fighter jets. The system is designed to save a pilot during an emergency situation by ejecting the seat out of the aircraft. Regarding the operational speeds of the ACES II ejection system, the information provided does not include a specific maximum knot speed for this ejection system. However, the historical context provided discusses experiments from the early 1960s that tested human tolerance to high-speed ejections at speeds of 1000 km/h with accelerations of 45 g. It also states that while living subjects are not used anymore, rocket sled tests have achieved land speeds of 10,000 km/h. The U.S. Air Force standard for human endurance to acceleration in the context is established at 10 gs, or 10 times the acceleration due to gravity, which is survivable for brief periods. These extreme conditions are part of the considerations in designing systems like the ACES II to ensure pilot safety during high-speed ejections.