My very first "real finless" model was back in '69, I think. It was a BT-20 payloader with a slightly larger payload section (this was also in the pre-"dirt loft" days). I had seen an article about closed breech launchers in Model Rocketry Magazine, then discovered the ARCAS was a CBL vehicle, and THEN got all excited about cutting drag as much as possible.

The launcher was built around a tubular shower curtain "rod" or possible shower curtain rod that I got somewhere. It had in inside diameter of just about exactly 24mm...a AR-2050 (or was it RA?) was a nice slip fit inside. So I built the model with a "faired" 2050 ring on the rear (I probably gained more base drag from that ring on the model than drag that I lost by omitting the fins...but it didn't matter...I mainly wanted to try out a CBL launcher!). I went across the street and flew the thing 3 times in rapid succession until, as I recall, the heavy payload section whacked the body on recovery. It flew arrow straight each time (it was very long [for a so-called competition model] measuring in at probably around 24" long). After that I recall the launcher gathering dust in my dad's workshop until I lost track of it when I moved away from home some years later. I still remember almost exactly how I built it and could probably "replicate" it today...flaws and all!

"Coning" is typical of most finless models that I have seen fly. I flew a 1/100 scale Saturn V that had finless upper stages and the second stage always "coned." I suspect that the coning for rockets that are "short and fat" would have a tendecy to be more severe than long and skinny models. I also suspect that they can more quickly reach the "point of no return" in pitch and yaw than a finned rocket. I further suspect that evey very small fins...possibly amounting to no more than "tabs" would go a long way to minimizing-eliminating coning and keep the model within a safe pitch/yaw envelope...but then it wouldn't be a "finless" rocket any more!

John Pursley