Bunny Rabbit Goonie Plans - Part 1: The fins!

The Thrifty Rocketeer sets sail...

So, if you're just joining us, I've decided to try to share some techniques I use for building low power rockets, but this is my second Bunny Rocket "Goonie".  I learned a few things along the way.

As you can see, my phone decides which way is up, not me.  Here's the basis for this rocket. You need the one-sheet from Peter Alway, which can be found on the internet, or in the files at WVSOAR on Facebook.  Look for "Rabbit Rocket Plans".  Because I can find a Baby Bertha more easily than a Big Bertha, that's the rocket we're modifying. You'll need some scissors to cut out the pattern templates of the fins (am I being too basic here?) and at least 9" of 1/8" Balsa wood sheet that is 3 inches wide.  Feel free to modify that if you've got scraps or a wider/narrower sheet of balsa that you want to work from.



You'll note that I have access to a photo copier, so when I printed out the one sheet plans, I laid that printed page back on my scanner and laid a white sheet of copy paper to mask off everything except for the fins template. By copying that, I then fed the sheet back through the scanner and again copied the same half page onto the other half of my copy. If done right, you have two (not mirrored) set of images of the fins, which you can then cut out, and still retain the full sheet of instructions and plans.



You can see that I screwed up slightly, as there is a slight overlap of text onto the end of the hind leg template.  I should have slid the original over another 1/4 to 1/2 inch, eliminating some white margin at the edge of the paper, and separating the two images slightly.

However, no matter, as we are only cutting these patterns out to use as templates for tracing/cutting...and as long as they are legible and you can see the recommended grain direction, this should work just fine.

You'll also note that all we need are the two images of the hind legs, and two for 2 paws and single copy of the cotton tail fin.  You've also got a pair of ear patterns that should be cut out of card stock, not copy paper. So, you now have an extra set.

I decided to share everything that I'm using in one photo, so pardon the repetition. Baby Bertha, one sheet plans, at least 9" of 3"-wide 1/8" balsa, a ruler with metal edge, box cutter (or Exacto knife), stick of school glue PASTE, an empty 2 litter bottle cap (for glue mixing), a kid's paint brush, some wood glue (I prefer Elmer's Yellow Carpentry glue)  and for scale and inspiration...my first rabbit rocket that I over-built with 1/4" basswood.


Again, sorry my phone continually flips the photos upside down. But you can see how I have laid out the templates to maximize usage of balsa wood...I've got it down to less than 9" but wish I could get it down to 8" somehow. Note that virtually all the wood grain directions align left and right, and that I have chosen to ignore that for the tail template, just to conserve wood. (Hey, the name of the blog is "The THRIFTY Rocketeer", alright?!)

Now, you can lay out your own templates as you see fit. I have backed them right up against each other, knowing that there will be a little sanding on each edge and the size of some of these pieces will be fractionally off, and rebuilt with some wood glue sealant and adhesive. I've laid a ruler along size for scale, and the original sheet of instructions just to fill out the shot. (Note in the upper left, the plans call for 1/8" or 3/32"...  3/32" is thinner than 1/8", and less strong.  You make your own decisions here.
Here's another brand of glue stick that I found,about as big as my thumb & more expensive.

I have already cut out the pattern/template (do I really need to show that to you?) and now I am applying a thin layer of school glue paste to the backside of the paper, getting ready to adhere it to the balsa in the correct position. I like doing this because I can re-position the pattern multiple times as long as the paste doesn't dry.  (Also, if you want to flip the templates around or over to make better use of your balsa wood, go right ahead. It makes no difference.)
(WARNING: Overnight drying will make it a b*tch to get that paper off, so cut and remove these templates reasonably soon!)
Once satisfied, I trace the pattern with a pencil (mechanical or fine point is best) in preparation for cutting them out.  Some people will prefer to cut with an exacto knife and skip this step. Just make sure you do a good job and sand down to the shape of the pattern before removing the template. 

Here I am slicing off the end of the balsa right along the straight edge of a hind leg. I find a metal straight edge to be easier to cut along. (Note I am also on my cutting mat, not on my wife's dining room table!  Please tell her.)  I prefer an exacto knife but have misplaced mine tonight. 

I have switched to an exacto knife blade refill, but I'm being very careful in holding the blade without an handle. I don't recommend doing this. After about 15 minutes of trimming and shaping, the dull side of the blade has worn my index finger pad down, though never cutting into the flesh! Ouch!

Another tip: When I used the box cutter above, it wasn't as sharp as I would have liked, and though I thought I had sliced all the way through the balsa (normally not an issue) the dull blade rode over a few stronger strands in the balsa and failed to cut through all the way. When I flexed the cut, it splintered back up the wood and peeled chunks out of the hind leg. Because this has never happened to me before, and I know I'm going to be applying wood glue along that surface to adhere to the body tube eventually, I'm not showing that mistake. In fact, I don't think I'll even mention it...

You probably know about sanding all cut surfaces of the piece you cut out, so I won't belabor that here. I have only this used sheet of 150 grit paper here, and I had a hard time positioning the shot, so excuse me.  PS: Used sand paper that has old paint on it WILL transfer the paint back onto balsa as we'll see later!

For sealant, I prefer to dilute my wood glue TWO drops of tap water to a half cap of wood glue for the first coat of sealant.  The higher water content makes it flow like water-paint, and dries quickly. It also will raise the grain of the balsa the first time around (in the first coat).  Additional coats after sanding and resealing will give you a more glossy smooth surface.  Those later coats only use ONE drop of tap water mixed with the same amount of glue.

Paint it right on, one side at a time. Coat the entire side right up to the edges. But wait-- if you have plans to feather the leading edge of any of these fins, do that BEFORE you start sealing!  Dried glue is MUCH harder to sand and shape (feather) than raw balsa wood.

So, we're back to sanding and feathering the leading edge. Note that I'm working on the tail fin here... and there's a build up of balsa wood dust on my sandpaper. Yes, some people are allergic to balsa dust, and you don't want it up your nose.  I think that's my pack of extra exacto knife blades in the upper left.

For the purposes of this demo, I am only doing the two front paws and tail fin, saving the two larger hind legs for later when I have more time. I will, of course, need to mix more glue for that in a larger quantity or a full bottle cap.  Also note that I pre-sanded all these fins except for one,  which I failed to shape before sealing. It required more hand sanding, and was harder.

Somehow last year, I made an extra set of BASSWOOD front paw fins from my first rabbit rocket. I have laid them out next to the balsa wood version as the sealant dries. Can you see the differences?

A final shot of  the wet balsa drying on the second side. Notice how the wood grain is rising, giving it a textured surface. This will have to be sanded down before the next coat of glue/sealant. Again, I'm holding off on the large hind legs only until tomorrow cause I'm running late tonight. (I stole borrowed this illustration from an old Semroc kit instruction below.)




Remember I said that used sandpaper with red paint will transfer earlier? Well, it did. Notice the red tint on the bottom fin when I feathered it after it was wet with sealant.  This won't be an issue, as I plan on priming and painting with gloss white at the end, but if you were trying for a natural wood grain appearance for some reason..... start with a fresh sheet of sandpaper!




Well it's time to knock off for the night, and I thought I'd close with a shot of the two wood glues in our house.  I prefer the left one, Elmer's Wood Glue at $2.00 a bottle at most Big Lotts, CVS, Lowes or wherever you can find it. They never fill these bottles completely though. The big brother on the right is a construction wood glue that many swear by, but this bottle left over from my wife's project is mostly gone, sluggish to pour, and was used to make the sealant slurry for this demo. It's the first time I've tried it. Not sure that it makes any difference. 

TIP: Keep these glue bottles mostly full if you can. The additional air inside the bottle helps to turn over the remaining glue inside over time. 

WARNING: If you leave Titebond in an unheated garage or basement over several years or a decade, it WILL separate into the most foul smelling substance that you will wish you had thrown out.  Buy fresh and use it up.  It's another reason why I like the Elmers' Wood Glue.  It's cheap, and you can use it up, and it dries fast. And it's strong. However, this replacement bottle cost me $3 at Jo-Ann fabrics today, which I think is over-priced. You can find it for under $2 if you shop around a little.

That's all for tonight. Thanks for reading through with me, and I look forward to your feedback.  I'll try to continue this project shortly and at least get up to the basic rocket assembly next time.

Until then, cap your glue and save your balsa scrap! (You never know when you'll need it!)

Comments

  1. Looks like your off to a good start. I'll be back for some more. Good luck.

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    Replies
    1. Thank you, er, "Mole". (You any relation to The Mole Man in Fantastic Four comics? :)

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