Tuesday, February 2, 2010

Changes in the Rules

Recently, there's been some nastiness over having certified G sparky motors. It appeared to some that the NAR was trying to ban sparkies under 160Ns total impulse. It appears, though, that recommendations made by the NAR panel to the NFPA (National Fire Protection Agency) will likely become part of NFPA 1125 (Code for the Manufacture of High-Power Rocket Motors) in 2011.

First, they decided to raise the upper limit of propellant in 'model rocket' motor from 62.5g to 125g. This simply means that full G motors, like the Aerotech G75J, that are under the 80N average thrust limit but over 62.5g propellant are officially model rocket motors. A good thing, though technically all motors over 62.5g (and reloadables) cannot be sold to those under 18, though it's clear that no one really pushes the issue.

Second, model rocket motors are restricted to solid propellant. That means that the 3 hybrid motors (West Coast Hybrids G55 and Skyripper G63 and G69) out there that are under 160Ns and under 80N average thrust are now grouped as high-power motors, along with all the other hybrids.

Third, model rocket motors had their maximum particle size shifted from 150 microns (0.15mm / 0.006") to 74 microns (0.074mm / 0.003"). This puts most sparkies firmly in the HPR category; however, sparkies with impulses under 160Ns will still be allowed, and new ones can be certified.

Fourth, any motors under 160Ns (G size or smaller) that violate the particle size, solid-propellant, or 80N limits will be certified as high-power motors and have 'HP' added to their motor designation. This includes about 25 G motors which will have their designations changed.

Fifth, there were a few certification changes. Maximum motor casing temperature was increased from 200 C (392deg; F) to 220 C (428° F). Provisions will be made for testing motors with interchangable and user-set delay systems, and manufacturer designations must reflect average thrust to within 10N or 20%, whichever is greater. I'm not sure why these changes were needed, but they all make sense.

These changes are not official yet, but stand a high chance of becoming so. They seems to me to do a good job of clearing the issue and making everything fair.

Story from Rocketry Planet
Dick Stafford reports and comments

From the RP story: a great picture that speaks a thousand words. Gary Rosenfield (L) of Aerotech and Anthony Cesaroni of CTI at the meeting. Competitors in business, but partners in making the rules good.

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