Rocketry Planet

WORLD WIDE WEB — The regulators of US rocketry, a branch of the Federal Aviation Administration, have just announced a long-awaited revision to the regulations for amateur rocketry. Despite the name, this affects the professionals as well as the amateurs ... and it's good news for everyone.

The original amateur-rocketry rules were written in some haste, decades ago. Some of their provisions turned out to be mistakes, and others no longer reflect reality very well. Everyone agreed that a revision was long overdue. Now, the FAA has announced a final version of revised regulations that appeared in draft form last year. The new regulations will come into effect in early 2009.

The "amateur rocketry" rules really govern all small-scale rocketry in the US - what makes a rocket an "amateur rocket" is its size and a few other design details, not who's flying it. The main intent of the amateur-rocket rules is to exempt little model rockets from regulation, and to minimise the paperwork burden on somewhat-larger rockets that are still small enough to avoid the complicated safety and liability issues of satellite launchers.

The one big change in the new regulations is in the definition of "amateur rocket" itself. The old definition set a maximum cross-sectional density (mass per unit of frontal area), a maximum total impulse (average thrust multiplied by time; this was essentially a size limit on the rocket), and a 15-second maximum total burn time.

The sectional-density limit was almost impossible for a sane rocket design to violate, and the size limit made sense, but the burn-time limit was a big headache. It wasn't out of line for solid-fuel rockets - which tend to have high thrusts and burn quickly - but it was a huge problem for liquid-fuel rockets, which can burn over longer periods. Liquid-fuel rocket developers mostly were forced to beg for exemptions from the rules, which were granted or refused seemingly at random.

The new definition eliminates the sectional-density and burn-time limits. It keeps the overall size limit set by total impulse, and adds two new restrictions: an amateur rocket must be unmanned, and it must be incapable of reaching an altitude above 150 km. (The unexplained numerical limits in the old definition reportedly were an attempt to implicitly set an altitude limit; now it's explicit.)

The new rules also require, as separate issues, that amateur-rocket operations be suborbital, and that they not cross into the territory of another country unless there is an explicit agreement with that country to do so. There are a bunch of other detail changes, mostly loosening past limitations and codifying past practices.

Most of the new restrictions clearly make sense. Rockets that can reach satellite altitudes (and hence might conceivably collide with a satellite), or are intended to reach orbit, or are likely to cross international boundaries, potentially can cause international incidents and hence arguably should get more scrutiny. And it's not unreasonable to decide that manned rockets likewise need a bit more attention.

The main importance of this for the entrepreneurial space community is the removal of the burn-time limit. With that change, many small rocket vehicles qualify as amateur rockets, at least for early development testing. (For example, many designs for the Lunar Lander Challenge would qualify, although perhaps not with their tanks completely full.)

This will make it possible for entrepreneurs and high-end amateur groups to do a lot of testing with minimal paperwork. Not only will this make things easier for them, but it should improve safety. Only testing can definitively prove that something works, and the more a vehicle is tested before it flies to high speeds and high altitudes, the safer those eventual flights will be.

Anything that hampers actual testing, forcing developers to rely more on analysis and computerised guesswork, hurts safety . . . and of late, the single biggest obstacle to effective testing has been the growing paperwork burden. The revised amateur-rocket rules, newly exempting a lot of small-scale rocketry from detailed regulation, are good news for everyone.

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