State of the Sport: Model Rocketry
I appreciate the rocketry article by John Boren in the June 2012 issue of Model Aviation. Several points in the article require elaboration.
First, the hobby is now generally referred to as “sport rocketry” and is comprised of model and high power rocketry. Model rocketry, in general, consists of rockets weighing under 3.3 pounds and containing less than 4.4 ounces of propellant (two “G” motors would typically contain up to 4.4 ounces of propellant). The AMA only permits rockets classified as “model” rockets.
High power rockets exceed the limits noted above. The “K” powered models featured in the article pictures are high power rockets. Two important elements associated with high power rocketry are:
- user certification
- FAA authorization
There are three levels of high power certification; the certification level required depends on the motor impulse class that the flyer wishes to fly.
Organizations and certification
There are two organizations that sponsor high power certifications:
- National Association of Rocketry (NAR)
- Tripoli Rocketry Association (TRA)
Membership in either organization is required for certification. Both organizations describe the certification process on their websites.
Part 101 of the Federal Aviation Regulations covers sport rocketry. In the case of high power rockets, a launch authorization/waiver process is required. Membership in a NAR or TRA club is highly recommended for those interested in launching high power rockets, as the clubs generally coordinate the FAA authorization/waiver requirements.
National Fire Protection Association document 1127 (NFPA 1127) defines high power rocketry. Total impulse is limited to 40,960 Newton seconds (Ns), which corresponds to “O” motors under that document.
The reference to a P-150 motor putting out over 40,000 Ns of thrust is incorrect. The abbreviation Ns refers to Newton seconds or total impulse of a rocket motor. Thrust is a measure of force, typically in newtons or pounds-force. A “P” motor, if it were permitted, would have between 40,960.01 and 81,920 Ns total impulse. The conversion from Newton seconds to pound-seconds is to divide by 4.45. The P-150 designation probably refers to a reloadable motor casing produced by Cesaroni Technology; P-150 is nonsensical as a sport rocketry motor designation.
—Stephen Lubliner NAR 22152 AMA 140687
Transcribed from original scans by AI. Minor OCR errors may remain.
