Composite Warehouse 5" Bullpup or Concept 125 (54mm x 3) - Which one needs built first?

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Composite Warehouse 5" Bullpup or Concept 125 (54mm x 3) - Which one needs built first?


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rfjustin

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So did you cut new forward fins(ref the last pic in post 116 above), or just mod the ones that came with for the pins?
I cut a 5th one that I use for mock-up to validate if my "pins" idea would be better than the original plan. Once it was identified as a preferred solution, cut the original 4 fins a bit to match the mock-up.
 

rfjustin

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Filled up with BB's and epoxy, curing in ice water to make sure the temps stay under control.

Will work on getting the canards on tomorrow...

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AdAstraPerAspera

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I would have thought you would have waited till the end with final weights on everything else to do the nose weight. How much weight did you go with, and where do you think that puts you CG/CP wise?
 

rfjustin

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I would have thought you would have waited till the end with final weights on everything else to do the nose weight. How much weight did you go with, and where do you think that puts you CG/CP wise?
About 2.5 lbs total weight, which should be good for up to a (4) grain 75. We will see if that needs to be adjusted in the future. :)
 

ECayemberg

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Enjoying the build(s)!

You know, the Bullpup would fly just fine in natural glass white at MWP next week! Looking forward to seeing both motor holders on the range!
 

JPX2000

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I cut a 5th one that I use for mock-up to validate if my "pins" idea would be better than the original plan. Once it was identified as a preferred solution, cut the original 4 fins a bit to match the mock-up.
Super idea. But I gotta ask… you’re using threaded pins, so did you tap the holes in the fins? And unless I missed something, could you explain why the fins were cut to only leave the tabs for the pins?
 

rfjustin

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Super idea. But I gotta ask… you’re using threaded pins, so did you tap the holes in the fins? And unless I missed something, could you explain why the fins were cut to only leave the tabs for the pins?
Thanks for the questions. Yes, I did tap the holes 4-40 to accommodate the pins. I left the tabs in place on the canards mainly to make sure I would not "come up short" where epoxy would flow and leave a little of meat on the bone. Using either a cut-off wheel or grinding wheel, I do plan to get a little dusty and sand off those tabs, or at least make them a bit less pronounced. I'll also knock down any other sharp edges or corners as I don't want to risk getting recovery gear snagged on main deployment.
 

rfjustin

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As odd as it sounds, this is the first build I have done where the tail cone is going on before the motor mount goes in. Motor mount gets dropped in from the top for a firm mate-up with the tailcone. Need to make sure the motor mount "bottoms-out" with the tailcone tight. There is not a lot of room between the 75mm Aeropack cap and where some bonding needs to occur.
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gerbs4me

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Tim51

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MWP will be coming too soon, wont have it done in time, maybe Bong in January/February? :)
In the meantime, do please feel free to post some gratuitous shots of the completed 75mm MMT / retainer assembly, the paint scheme etc for those of us watching from a distance 😊
 
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