Brief:
My rocket with removeable/replaceable fins. 3 fin roc. I wanted to test different fin material so I came up with this. I can change fins in a few seconds, type or design. You are limited to 1/8" fin stock unless you used a 1/32" spacer on the side of each fin, then you could use 1/16" fins. Gasket material, G-10 or ply can be used for a spacer. I like the 1/8" fins so I haven't tested that yet.

Construction:
3 2.6" airframe sections 18", 23" and 6" for alt bay 2 2.6" couplers 1 2.6" nose cone 1/8" 5 ply birch for fins 1/16" G-10 for fin mounting points 6 1/4" alluminum screw posts, AKA Chicago Screws (available at OSH) 1 38mm 14" motor tube 20' of tublar Kevlar® 28" top flight chute 1/4" launch lug material 3 3/16" CR's 2.6" to 38mm

This is a complicated rocket to build. I cut 1/4" slots in the airframe for TTW attachment of the fin mounting points. I epoxied 2 CR's to the front portion of the motor tube to keep it centered while I did the TTW attachments. I took 1 fin and 2 of my G-10 attachments, put them together and stuck them TTW to the MMT. I CA'd the G-10 parts on and removed the plywood fin. Repeat 2 more times, and apply inside and outside fillets with 30 min epoxy. Now I have 1/8" slots for the fins to go in between the G-10 mounting points. After the epoxy was dry I inserted the fins and drilled 1/4" holes for the screw posts, through the G-10 and fins at the same time. These are what hold the removeable fins onto the airframe. This is a very sturdy rocket that I glassed with 4oz fiberglass. Construction rating....5

Flight:
I would use F-40-4 as the smallest possible motor, and I will fly it on the J-350 in Black Rock this summer 2001. I used standard cellulose wadding and 20' of Kevlar® for shockcord. I flew it on the F-40-4 reload for the 29mm 40-120 case, and I must say this is the smallest motor that will lift it. The F-52 is a little better, and it flies great on a G-64-7. The 28" chute brought it down softly from about 700'. Flight rating....5

Summary:
Pro's...... You can replace broken fins, or just redesign it whenever you want. I like to test different material types......Lexan, G-10, plywood etc. Con's.....None

Other:
It is hard to allign the fin mounting points, so make sure you barely tack 'em down with CA so you can break it free if need be.