Balsa fin excess

The Thrifty Rocketeer continues...

 OK, here's where this blog earns its name... "The Thrifty Rocketeer"!

 For several years, I have been puzzling over an aspect of model rocket kits that confounded me.  That is, it has been a question that pops up at least once during each build session, but then gets swept aside until either clean up, or gluing inside a body tube.  You'll see what I mean...

 In today's modern technology, we have eliminated the need for templates and patterns to be traced and cut out of fin stock.  Instead, we advanced first to the die-press plates that stamped or "cut out" the fins so that all the new rocketeer had to do was simply slice the few remaining bridges or tabs to complete the outline of the fin.  Presto!  With a little sanding, you had a perfectly shaped fin, with the wood grain correctly oriented for strength.

 The next phase was the introduction of laser cutting of fins, again with minimal balsa wood bridges or tabs left to be sliced through.  Although I have seen only one or two of these mis-fired, or mis-printed (if you forgive the mixed metaphor), this technology would almost seem to be fool-proof... producing exact dimension fins that barely need any cutting or sanding to complete.  And the duplication of exactly identical fins time and time again, would just seem to be nothing short of miraculous.

 If we can get THAT sort of precision and exact measurements out of our fins, then it follows to ask, "WHY are the margins (flash) or excess borders of a sheet of balsa SO LARGE?"

 I mean, why can't we be even more efficient and reduce the amount of excess that is trash or to be eliminated?

 I asked this question on a Facebook page devoted to Model Rocketry recently and sparked a long and vigorous debate about why it was necessary to have such large margins around the sides of fins.  The reasons given ranged from:

  1. The excess is intended to be used for repair of said fins if it should become necessary
  2. The excess is needed for the compression die to grip onto before being sliced by the die
  3. The excess balsa is used for spare fins in scratch builds
  4. The excess balsa is used as glue sticks or spreaders to dip into glue bottles and apply
  5. The excess balsa is a function of "standard width" balsa sheets that are sold en mass
  6. The excess balsa forms a frame to protect the fin which has been traced out within the sheet
There were a few more responses as well, but you get the drift.  Nobody really knows the definitive answer, and all have come up with a use for the excess.  One rocketeer even went as far as threaten me if I started a movement to eliminate his source for scratch build fins and designs!  (Well, it was in jest, but still...)

Now, I have heard that there is a world-wide shortage of balsa wood, and that's why nosecones are now being made from "blown white plastic" instead of turned balsa wood.  I can understand the shortage of certain lengths or sizes of wood at various times, but a "world-wide shortage"?  Really?

If that's the case, the laws of supply and demand will surely drive the cost of balsa up, up, up... and that will be reflected in the price of kits to the end-consumer. (oh, wait...)

And if that's the case, then why aren't more balsa trees being planted and plantations being built?  I understand the tree grows best in Mexico, Peru, Columbia and other tropical locations.  Why aren't more rocketeers investing in balsa plantations or even a couple dozen trees to be grown in out of the way corners of existing farm land in warm regions?

The trees grow fast, only six years or so to maturity, producing a soft, somewhat spongy bark and wood.  I would imagine the harvesting and processing of the tree would require some expertise, but could be handled by the existing tree-trimming and harvesting operations.

I understand there are some economies of scale that might make one's own private grove of balsa trees impractical.  But it does give you something to think about in your retirement, doesn't it?

It all comes back to why the excess around the fins that have to be laid out along the grain in a very specific pattern on each sheet of balsa.  Why not pack more on each sheet of balsa, or lay them out on smaller pieces?

I think these are only reasonable questions.

If you come up with any answers, I wanna know.  Share them in the feedback, will you?

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