You have an H64-8 rocket motor which has total impulse 320.00 Newton seconds. What is the approximate burn time for this motor?

You have an H64-8 rocket motor which has total impulse 320.00 Newton seconds. What is the approximate burn time for this motor?

• A. 3 seconds
• B. 5 seconds
• C. 8 seconds
• D. 10 seconds

Answer: (B)

Burn time is found by dividing the total impulse by the average thrust. For this motor, the total impulse is 320 N·s and the average thrust is 64 N. So the burn time is approximately 320 divided by 64, which equals about 5 seconds. Note that the number after the dash indicates the ejection delay after burnout, not the burn duration itself, so the 8-second delay is separate from the burn time.

Burn time is found by dividing the total impulse by the average thrust. For this motor, the total impulse is 320 N·s and the average thrust is 64 N. So the burn time is approximately 320 divided by 64, which equals about 5 seconds. Note that the number after the dash indicates the ejection delay after burnout, not the burn duration itself, so the 8-second delay is separate from the burn time.