Wednesday, March 22, 2017

Estes Nike Smoke #7247 Build, Part 6, New, Harder Fins

I've described how to shape this style fin in the past on the blog:
http://modelrocketbuilding.blogspot.com/2016/06/shaping-estes-nike-smoke-fins-part-1.html
http://modelrocketbuilding.blogspot.com/2016/06/shaping-estes-nike-smoke-fins-part-2.html
http://modelrocketbuilding.blogspot.com/2016/06/shaping-estes-nike-smoke-fins-part-3.html
http://modelrocketbuilding.blogspot.com/2016/06/shaping-estes-nike-smoke-fins-part-4.html

 And in the Apogee Peak of Flight newsletter:
https://www.apogeerockets.com/education/downloads/Newsletter357.pdf

Just what you wanted - HOMEWORK!
I won't be going into detail on how to shape the fins here on the blog. Use the addresses above to see one way to do it.

I'm building two Nike Smoke kits at the same time. While one kit had dense hard balsa, the other kit balsa was too soft. Press a fingernail in a border area to see if your balsa is soft. If it gives too easily to pressure you might want to buy some stiffer wood and cut out your own fins.
Shaping Nike style diamond tapered fin requires harder wood. The final fin shape will be thin.

There is so much extra wood on some laser cut sheets I cut more fins from what was left from the harder kit sheet.

With the edges glued back to back I had enough area in the center to cut four more fins.









Sand the edges flat and glue them back to back. The pencil tracing shows how the new fins were drawn.
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2 comments:

  1. ScottMarch 23, 2017 at 12:48 AM

    Smart!

    I had a fin on the Sprint XL where it looked as if two sheets of wood were glued together - of different density even. The glued joint was week and two of the three fins wobbled at the seam. Still they were attached, but wiggling the fins a tiny bit showed the weak joint.

    Should I break the joint and re-glue, form new fins or harden the fins with paper? Any preference? Or so long as the wood grain is aligned properly to the rocket tube, all should be well.

    Inquiring minds...

    ReplyDelete
    Replies
    1. Chris MichielssenMarch 23, 2017 at 3:13 PM

      Hi Scott,
      That's a judgement call you'll have to make depending on where the two pieces are joined and how hard the wood is. I did it on the Nike kit because I wanted harder wood when forming the diamond taper.
      I wouldn't recommend breaking the joint, you might end up with a bigger fix than you started with. You could use some CA glue over the joint, that will strengthen it and would be easy to sand smooth. Once the root edge is glued on the body tube it should be strong enough.
      I don't normally paper fins. Papering would be difficult on this model given the fin shape.

      Delete

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