Sunday, September 28, 2014

More stuff I use to build rockets...

Continuing on with tools…
  • Alignment guides – In my last post, I mentioned alignment marks for fins, launch lugs, etc. When you build a kit, it usually has an alignment guide printed in the instructions which is to be cut out and wrapped around the body tube. For unusual designs like the Estes Interceptor, you still should do this; however, for most LPR rockets there are other ways. You can print out your own fin wrap by using online tools, such as those at Payload Bay. Or you can spend few bucks to buy a fin alignment guide set from Estes, which contains the yellow parts in the pic below:
The set has a long v-shaped piece of plastic (bottom of image), which can be used to draw fin lines on BT-50 and smaller tubes. For larger diameter tubes, I prefer the aluminum T-shape above it – you can use it to draw nice straight lines down the body tube, which beats the heck out of the “use a door frame” method mentioned in the old kit instructions. The circular plastic pieces are used to place fin marks at the bottom of the tube; just pick the one that fits and draw the marks above the lines in the plastic. Works great with 3 and 4 finned rockets!
  • Filler – For filling tube spirals, you can’t do much better than Elmer’s Fill N Finish (shown above), available at hardware stores or online. Mix it with water until you have the consistency of mustard, and apply it with a brush to the spirals. Let it dry a few hours, sand the tube with 320 grit, et voila! No more seams. You can also use it to fill the grain on balsa nose cones and fins, but I don’t use it much for this purpose as it does not harden the balsa the way sanding sealer does. I DO use it often to fix dings in balsa parts and fill gaps – can’t live without it! Fill N Finish is non-toxic and cleans up with just water, so it is good to use with kiddos around.
  • Sealer – This is the old school and stinky way to fill balsa grain. Shown below is Aero Gloss Sanding Sealer, available at local and online hobby shops. Multiple coats (4 or 5) applied with a brush to the fins or nose cone will give you a hard balsa surface with a smooth plastic-like finish unachievable by other methods. However, the fumes will kill ya, so use in a well ventilated room or outdoors. Not safe for the kids or around the wife, who will unleash heck upon you for stinkin’ up her house!
  • Masking tape – Most paint schemes call for different colors on the various parts of the rocket, which means masking. Here, the choice of tape is all-important to get nice sharp lines and avoid bleeds. You do NOT want to use the blue 3M tape shown below; it was designed for house painters, not rocket builders, and makes for terrible bleeds. Some folks swear by Scotch transparent tape and have good results, provided they spray an additional coat of the base color after masking and before the final color (this helps seal the tape edges, avoiding bleeds). I use the Tamiya yellow tape at the top of the pic – it comes in different widths, conforms well to the surface, and adheres nicely. Much more expensive than Scotch tape, it is also very forgiving; I have never had a bleed using this stuff.

  • Paint – Pretty much a personal choice. I use Industrial Krylon (a laquer based paint) because it is resistant to running, dries quickly, and you can recoat anytime. Others use Rustoleum or enamels, though the latter take a LONG time to dry. Still others forego the rattle can to get spectacular results through airbrushing.

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