Boat Tails for MMX

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I keep designing parts for MMX. In addition to nosecones and transitions, we need some boat tails as well. I’m on the road the rest of this week, but I got some time to play last night, and I created new parts. BT-3 sized boat tails - straight conical and ogive-based, and I got the idea for a set of sci-fi looking vanes you’d use for show (or say, a BT-3 based Interceptor).

Also started designing a BT-3 replica of the Interceptor nosecone. It’s a complex one with lots of subtle elements. I’m using an Interceptor E nosecone (2 inch diameter) and scaling it down to BT-3. A few hours later, it’s ready for an initial printing once I return home. You could spend a week on CAD just adding all the subtle details in the large nosecone. I plan to add a few detail elements to it and call it done. The ones on the big nosecones are etched into the plastic-mine will be slightly raised. I’ve found the raised ones are visible, and they are easier to create as a bonus. The CAD can do it and so can the resin printer, but some details are so subtle the eye doesn’t catch them. I added bolts on the access doors of my BT-4 Nike Smoke nosecone and you can’t see it, even though you can feel them with your finger. Live and learn. And print another iteration.

I’ve completed the transition sets. I now have transitions (plugged, with attachment points on both ends) for all combinations of tubing from BT-2 to BT-20 (BT-2, 2+, 3, 4, 4+, 5, 20). Although I developed them, I don’t plan to do much with the BT-20 size. Most of my work will be in the BT-2 to BT-5 area. Maybe nosecones for some BT-20 based Gooneybirds. Yeah, I’d do that.
 

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I decided to develop some mini-motor items as well. There are enough nosecones for BT-5 and BT-20 kits, except for the odd ones like the Phoenix or Honest John (OK, I want to design a BT-5 Phoenix just for the challenge of it. And a BT-5 V-2 as well….will have a 2” long airframe). I can find nosecones starting at BT-5, but try to find tailcones and you realize there aren’t many. So while I’m getting together MMX supplies, why not fill in the mini-motor line as well? As I look at some kits to downscale because they are just awesome kits, I realized that some will need more motor than MMX can supply, even scaled down to a BT-2 airframe. For example: Andromeda, Explorer Aquarius come to mind. So we will need to downscale some rockets to mini-motor size to keep them flyable.
In addition, there are some kits where fans would like to have the kit in multiple sizes: MMX, 13mm, 18mm, 24mm and 29mm (and maybe even 38mm). I’d hate to dampen their fanaticism. I have 3 different Falcon Commanders I have to build from Ollie-OOP Rocketry. His 13mm kit just has a conical cone—no cockpit. I added a cockpit to mine nosecone by using Sculpey, shaping it with a knife and hardening it in the oven. Came out great! But we need a printed BT-5 nosecone with a cockpit for those kinds of kits. Added to the list.

Image below is mini-motor boat tails for BT-20 airframe. A BT-5 (13mm) motor tube slips inside the 18mm boat tail. The two on the right are for the sci-fi look, like an Estes Interceptor tailcone. I’m making those for all tubes BT-3 and up.
 

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