Well, there are rockets from last year still unfinished, and maybe I can get a little done on them tomorrow, but today’s weather wasn’t good. So I’m starting one from the build pile.
The Estes Scion is kind of an odd kit. It’s a web exclusive, available only through the Estes site, not retail channels. The packaging is simply a plastic bag, without a face card. The parts are essentially the same as for the Leviathan, except that there are two pieces of 3″ tubing both 21.5″ long for the airframe — outleviathaning the Leviathan. Neither one is slotted; you have to cut your own slots. The fins are the same as the Leviathan’s but in the Scion design they’re flipped front to back, so they sweep forward. And there are only three fins in the design… but there are four (packaged together in a small bag) in the kit. Seems clear this is a SPEV (Spare Parts Elimination Vehicle). What with the minimal packaging, cut-your-own slots, no retail markup, and use of existing (surplus) parts, you’d think this would be an inexpensive kit, and it is, $29.99 (plus shipping). Compare that to $44.99 for the Partizon, Ventris, and Argent. But then compare to $22.50 which is what the Partizon, Ventris, and Argent have been on sale for these past several weeks while the Scion is still at regular price. Well, even so it’s pretty cheap.
The Leviathan’s out of production now, but you could bash one from a Scion kit if you wanted to. Or you could turn it into a Patriot, or go nuts with the parts and your own design. Or you could, well, build a Scion. Which is what I’m doing.
One more oddity about the Scion: there’s no thrust ring. Which wouldn’t be surprising except that Estes is no longer designing rockets for composite motors. The recommended motor (singular) for the Scion is the F15-4. So the instructions tell you how to put a tape thrust ring on the motor. Why they went that route instead of including a thrust ring for the motor mount I don’t know.
Estes claims a weight of 16.5 oz for this rocket, and the diameter is 3″; toss those numbers in at thrustcurve.com and it says the speed at the end of a 6′ launch guide is 33 ft/s, way below what thrustcurve considers acceptable speed (about 50 ft/s). Maybe on a calm day you could get away with it, but I’m thinking I’ll stick with higher thrust composite motors. Definitely no glued-in thrust ring for me.
The first step is to cut the slots, for which Estes provides a template. I made a copy rather than cutting out the original, checked the size versus the original, and then checked it against the airframe tube. It passed the first test but failed the second. Too small! Just by a couple millimeters; you could probably ignore that and no one would ever spot it. But I made a new copy scaled to 101%, and that was nearly perfect. There’s a couple ways to go here. You can cut out the slots in the template, use the template to mark the tube, and then cut out the slots in the tube, or you can tape the template to the tube and cut the slots directly. Both ways have their advantages. I went with the second. Some people like to use a Dremel cutoff wheel to cut slots, but for relatively thin wall tubing like this, I find a snap blade knife and an aluminum angle work fine. Next step is to build the motor mount. I started gluing on the centering rings as instructed, then realized I wouldn’t be able to do internal fillets that way. So I glued on (with epoxy) only the third ring, about 1⅛” from the forward end.The other two will get glued on later. Oh… I should’ve cut a notch for a Kevlar leader before doing this. Well, I’ll fake it.