06-12-2018, 04:58 PM
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Master Modeler
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Join Date: Jan 2009
Location: Fairbanks, Alaska
Posts: 6,507
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Quote:
Originally Posted by Earl
Jason-
I glanced through the thread somewhat quickly (and possibly you've already noted it), but the 1340 used heavy walled tubing that was thicker than the standard Centuri ST-13 tubing (Semroc/eRockets would have it). The 29mm motor mount tube (also heavy walled) is a "glove fit" inside that tubing.
The O.D. of this heavy walled ST-13 tubing is the same as the regular ST-13 tubing, but because it used a thicker tube, the nosecone was different than that used in the Phoenix Bird, Eliminator and other kits that made use of that similar looking plastic cone. I think the cone profile was the same; what was different is the 'shoulder' had a smaller O.D. to account for the thicker tube wall.
That said, the nosecone and fin unit from an Estes Eliminator can be used to make a nice clone...it just won't be as 'beefy' as the original 1340. The fin unit is the same between all kits that have used it off and on now for 46 years. It holds up well under F power from what I understand, but I think Jerry Irvine has reported fin flutter/fin breakage under G power.
Earl
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With 3D printing, this is no longer a problem; files could be generated for printing "wide shoulder" (Phoenix Bird) and "narrow shoulder" (1340 Sounding Rocket) nose cones and tubing couplers. Thank you for reminding me about the thick-walled tubing (*and* for pointing out where it can be sourced!); looking at the 1340 and 1340/20 pamphlets last night, that notion--about the tubing thickness, given their very powerful motors--was "tickling" at the edge of my awareness, and:
I hadn't known that the 29 mm motor tubing "sleeve fits" into that thick-walled body tubing--that is good to know! I have relayed your information to Bruce Levison ('teflonrocketry1'). Thank you also for passing along Jerry Irvine's report about the fin unit's "F-power limit" (for avoiding fin flutter and breakage under G power). F power is plenty strong for me, but maybe (for those who'd like to use G power safely) a somewhat "beefier" duplicate of the fin unit could be 3D printed (slightly thicker gauge, perhaps?)--or maybe the fin unit in the Estes Eliminator might be strengthened with Kevlar veil and epoxy--to withstand the stresses from G motors.
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