Wednesday, March 12, 2008

Proof that a 0FNC can work

In sport rocketry, 3FNC stands for 3 fins and a nose cone. In other words, a garden-variety rocket. I've posted a lot about rocket stability, which in a 3FNC is governed by the CP/CG relationship. One of the basic things that affects CP is the fin size, shape and number. So, what happens if the number of fins is zero? Ignoring, saucers, pyrmids, cones and a few other designs which don't fit the 3FNC mold, my answer would be skywriting. Through the years I've seen numerous discussions about this possibility. A common example would be someone wanting to build a scale Gemini-Titan II and thinking clear plastic fins would spoil its scale look. I might rely too much on computer sims, but I just can't get my mind around the idea of a finless rocket. However, in every thread, there is someone who claims to have successfully done so. I'm dubious, as hard evidence is to my recollection never provided. I'll also exclude modrocs with gimballed motors, THAT's CHEATING! (an example is Cristiano Casonati's Casimiro)

However, today I found evidence. In the April 1982 California Rocketry, there are photos of a finless rocket in flight. It was built by Korey Kline (an early innovator who also pioneered Desert Squids and monocopters). there wasn't much detail, but it flew on canted D12s and featured a central launch lug to facilitate it spinning. Hmmm, is spinning also cheating? Or, is it necessary?

I think I may have seen another example from 'across the pond', but can't place where at the moment.