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Pop Fin Tutorial With Video.

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K'Tesh

OpenRocket Chuck Norris
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Over on FB, a builder has cut some fins with the grain that didn't go parallel with the root edge, or the leading edge, leaving a large area that is "pop fin" like. I'm can't find a tutorial that shows a comparison on how different fin grain alignments corresponds to fin failure points. If I were back in the states, I'd have the resources to do this myself, but here in China, I can't. Could someone make up a few sample fins cut to the same shape (say similar to the Der Red Max, or Goblin) with grain running parallel to the root edge, parallel to the leading edge, and one that is something in between, and then test them to destruction. If you're really ambitious, perhaps going to the point of redoing the test with papered fins, and sealed fins, and if you're super ambitious, using different glue methods (CA vs double glue vs epoxy).

Thanks!
 

Incongruent

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Over on FB, a builder has cut some fins with the grain that didn't go parallel with the root edge, or the leading edge, leaving a large area that is "pop fin" like. I'm can't find a tutorial that shows a comparison on how different fin grain alignments corresponds to fin failure points. If I were back in the states, I'd have the resources to do this myself, but here in China, I can't. Could someone make up a few sample fins cut to the same shape (say similar to the Der Red Max, or Goblin) with grain running parallel to the root edge, parallel to the leading edge, and one that is something in between, and then test them to destruction. If you're really ambitious, perhaps going to the point of redoing the test with papered fins, and sealed fins, and if you're super ambitious, using different glue methods (CA vs double glue vs epoxy).

Thanks!
Would many pictures work instead of a video?
 

K'Tesh

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A video would be preferred, as the viewer can see and hear what's going on. However, if the pictures show how the testing is done I'm sure that would help get the idea across, just not as well as a video.
 

Rex R

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it is my understanding that running the grain parallel to the leading edge might not be ideal...however it is an easy rule to remember. it was suggested to me a while back that using a 10% chord rule might be better for one of my birds. run the grain parallel to an imaginary line running from a point 10% back from the root chord to point 10% back from the tip chord(see my hand drawn pic) also shown is a 20% chord. not quite what you're looking for but it is a start.
Rex

finchord.jpg
 
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