NAR HPR Propulsion Systems & Motor Classification 2

Question 1

What does the letter designation in a high-power rocket motor code (e.g., 'J' in J460) indicate?

Accepted Answer

Total impulse range of the motor

Answer

The letter in a motor code designates the total impulse range, where each successive letter doubles the impulse of the previous one.

Question 2

A motor designated as 'K1100' has an average thrust of 1100 Newtons. What does the 'K' prefix tell you about its total impulse?

Accepted Answer

1280–2560 N-s

Answer

K-class motors have a total impulse range of 1280–2560 N-s, which is double the J-class upper limit.

Question 3

Which motor class is the LOWEST that requires NAR Level 1 High-Power certification to purchase and fly?

Accepted Answer

H

Answer

NAR Level 1 certification is required for H and I class motors; H is the lowest HPR class.

Question 4

What is the purpose of the delay charge element found between the propellant grain and the ejection charge in a composite motor?

Accepted Answer

To allow the rocket to coast to apogee before ejection fires

Answer

The delay element burns at a known rate after motor burnout, giving the rocket time to reach apogee before the ejection charge deploys recovery.

Question 5

APCP composite propellant consists primarily of which two main ingredients?

Accepted Answer

Ammonium perchlorate oxidizer and aluminum fuel

Answer

APCP (Ammonium Perchlorate Composite Propellant) uses ammonium perchlorate as oxidizer and aluminum powder as fuel, bound in an HTPB or similar polymer matrix.

(NAR HPR) NAR High-Power Rocketry Certification Practice Test

(NAR HPR) NAR High-Power Rocketry Certification Practice Test

NAR HPR Propulsion Systems & Motor Classification 2