My Concept 150 Hybrid II

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Dave A

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Jan 22, 2013
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I posted this under "Techniques" thread because I used a lot of different techniques vs. my usual Level 3 builds.

Aft FG Section.jpgFwd FG Section.jpg

I built my last 6" rocket with a FG motor tube, big mistake and added too much weight.
This new one I call the Concept 150 Hybrid II. It utilizes the 6" Concept fin can and the airframe is a "hybrid" of PML tubing in the middle and approx. 24" of FG tubing on each end. Face it these ends take most of the beating. I used long pieces of 6" couplers to mate the pieces and used them to double-wall the center section. All of these were scraps, cut off parts and leftover CRs from my IRIS project.
I easily decided to make it without a motor tube and located plywood rings to accommodate a 4-grain, (the 5-g uses the same fwd ring) then another ring for a 6g (works for my M-Contrail Hybrid motor, too)
Its a hybrid construction and designed for Hybrid motors: Hybrid II

AFt Interior View.jpgMotor Section.jpg

One view shows the thrustplate; the second view shows inside with threaded rods tying all the centering rings from the forward most ring down to the thrustplate.

AL Thrust Plate-Retainer.jpgConceptt 150 Fincan.jpg

I was not impressed with this older version of the fin can. The cloth inside appears to be CF but the fin sections were hollow and flimsy.
I drilled fill and vent holes in them. I injected spray foam to fill them close to 90%. Made them much stronger doing that fill process.
The fincan fits the aft end fairly snug. I plan to drill and epoxy small sleeves in the fincan body to match t-nut inserts in the centering rings so it will bolt onto the rocket

The assembled Concept 150 main airframe section as I have shown weighs 5 lbs less than my old IRIS (that has CF panel fins and FG motor tube and a lot more epoxy used)
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