The Value of Scrap Balsa

 The Thrifty Rocketeer blog continues....

Have I ever told you that you should save your scrap balsa?  You know, the extra flashing that's left over these days when a laser cut fin or rudder or other part is cut for you?

Yeah, sure I have. So much that you're sick of hearing me say it. 

But today, I'm going to tell you a story of WHY you should do that.

Did you know that back in the day, Estes Rockets and other companies used to send you a sheet of balsa on which you laid out your pattern for your rocket fins... struts...stabilizers...rudders...braces... everything!  This is back in the day before the internet... before laser cutters... before blown plastic nose cones... before so many of the modern conveniences that we take for granted.

You used to have to lay out your traced patterns (nobody had access to scanners and photocopiers)  on the sheet of balsa with the grain oriented the right way, so that the piece had an internal strength to it, and wouldn't fracture or sheer off the body tube when stressed.

We still do this, but not as much as we used to.  The fins are laid out in a pattern so that the grain is already taken into account.  In fact, this practice also leaves even more excess flashing than before.

So what?

Well, this last week, somebody posted a picture of a glider that they had made from an "archived" two-page instruction sheet from Estes.

Once upon a time, Estes not only sold kits, with the materials that you needed to assemble the rocket... but they also distributed photocopied or printed instructions to their regular customers too.  These were homebrewed kits for the crafty to build from scratch.

Now, since I wasn't around back then, I can't speak to just how this worked, but there was a semi-annual design contest that would see the best design distributed to loyal customers, complete with parts list, measurements, patterns and instructions. 

I don't know how long this lasted, but I know that it must have run between 1961-69, though the prime years may have been 61-66.  

I don't know how many still exist today, but you can go look at these plans yourself, at https://www.spacemodeling.org/jimz/eirp.htm  or email him at JimZ_rocketplansguy@waywow.com   It's  my understanding that Jim allows you to look at all the files, and if  you use one, he asks you to make a donation to help support the archive.  At a minimum of $2 per payment, that's a bargain!

So somebody (don't worry, Michael, I won't mention your name) made one of these "Raven" rocket gliders and posted the picture of his craft on Facebook.  He or someone else posted the link to the archive file for the two page instructions. That's where I saw it. And by clicking on the pages, not only could I expand them, but I could read through them and consider building it myself.

Now, there are at least two problems inherent to this idea:

  1. There's a parts list, but the parts numbers are from 1973...and are 50 years out of date.  If you can convert the part numbers to the modern day replacement, you can order that nosecone, or body tube or baffle and try to build the bird.
  2. There is no scale on the instructions...no ruler, so you can't expand the plans easily to the right size to use the patterns.  Maybe there is a way, but I don't know it.  So I am faced with the problem of figuring out how to layout the plans on a sheet of scrap balsa that I have.  But if you have a pattern that consumes the sheet of balsa and know the square dimensions of the sheet (ex: 3"x 9" x 1/8") you can interpolate.

This is what faced me as I looked down the list of contents.  I recognized the nosecone, fin sheet, support structure sheet, launch lug, reinforcing sheet of adhesive paper,  paper clip, glue, and "lead shavings" for what they were.

And it occurred to me that I needed to learn how thick a BSF-10, BSF-20 and BSF-40 were.  A fellow rocketeer pointed out to me that the sheets were multiples of 1/32" ... that meant the BSF-10 was one times 1/32" thick.  The BSF-40 was four times the 1/32" or 1/8" thick.  From this, I could proceed.

And here's the point:  I proceeded to my pile of left over scrap balsa pieces, and began examining what thicknesses I had and in what size.  I was able to determine that I needed 9" of 1/8" balsa to be sliced into a quarter inch wide fuselage strips.  And from there, I could position the rudder and other support struts to fit the scrap I had.

But I didn't have enough 1/16" balsa to lay-out two nine inch by three inch triangle fins. I needed an entire sheet of that BSF-20 stuff. A trip to Hobby Lobby was going to be necessary after all. (It was $6.08 total with tax. I used a quarter of the length to make my fins)

The launch lugs were no problem, as I had left over straws and could easily cut one to fit. But it was the nosecone that was going to be the problem.  I didn't have any extra BNC-20a nosecones.  Now, I could tell you a tale of how I stacked up pieces of flashing and excess balsa until I had build a block of balsa and created my own nosecone.  

But that's not what happened.  I couldn't see the value to gluing pieces of balsa together to build one. Oh sure, I could build up layers until I had a block of 5/8" balsa... but I had no lathe for turning...and the balsa would be impregnated with wood glue... making it harder. I couldn't see whittling it down.

So I turned to my wife's left-over scrap from her shelving unit. Someone on TV had recommended placing wall bookshelves around the living room so the cat could climb high and be happy.  And the wife had started a cut and then backed out of it.  As a result, I had a 3/4" pine board remnant that I could cut the block out of.  It was 5/8" square by about 1.5" long when I started.

I sanded the corners off the block, rounding the edges, and slowly shaped it by hand. Round and round I went, forming the shoulder that would be inserted into the body tube (a BT-20J) first.  And then, by hand, I scrubbed and sanded this pine block down into a bullet shape. It's not perfect, but it fits, and will be far cheaper than the $5 part I saw listed in a catalog (plus shipping!)

When all was said and done, I reused pieces of balsa, straw, address labels, straight pin, and made a pine block plug, as well as one left over motor mount tube (BT-20) that I had laying around.  The total cost of materials that I had to buy so far (not including wood glue, paint or sandpaper) has been $6.08 for the sheet of BSF-20 3"x9"x3 ft.... and I've got more left over.

That's not a bad investment for a photocopied set of instructions that I printed off the internet. Yes, I know, I sent JimZ $2 for the use of the plans, but still, I used all this left over flashing and excess balsa that I had saved for years, and was able to build the rocket boost glider from scratch!

Now THAT's a Thrifty Rocketeer project!

So let me say it again, "Save your excess balsa scraps ...(including that excess 27" sheet of BFS-20)... cause you'll not have to buy all your materials next time."
...unless you want to... and money is no object.

This has been the Thrifty Rocketeer.


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