Hello All,

Small scale model rockets (BT-5/ST-5 - BT-20/ST-7 size) often have a problem: On such models, even the thinnest standard "gauges" (thicknesses) of balsa fin stock and fiber fin stock frequently yield fins that are noticeably too thick for such scale models. I have found a very simple and very cheap (virtually free, in fact) solution to this problem (please see below):

A few years ago I built a proof-of-concept, BT-5 size Black Brant VII scale model (see: http://www.flickr.com/photos/48113599@N04/4975456194/ ), whose fins are made of laminated card stock from an Estes kit insert card. (I just found this model tonight at the bottom of one of my desk's drawers, and its fins are undamaged despite having been under CD-ROM diskettes and papers.) To make the fins, I cut out four "V-shaped" pieces of card stock, each of which I folded in the middle (down the centerline of the "V") to create a set of 2-ply fins. The fold is where the leading edge of each fin is located. Then:

I coated the inside (the printed side) of each fin with white glue and pressed it together between two sheets of wax paper to squeeze out excess glue, and then I laid weights atop the fins on a flat surface. (I used just enough glue to cover the bonding surface on one half of each "V.") The resulting 2-ply white card stock fins are perfectly flat, stiff, and very strong--and they are only 0.5 mm thick! Using Stine's "double-glue joint" method, the card stock fins were (and are) bonded very strongly to the kraft paper body tube. The fins on the Black Brant VII model look scale, in thickness as well as in planform. If the fins on other scale model rockets need to be thicker in order to appear scale, three or more layers of card stock could be laminated together using white glue or yellow glue.

I hope this information will be helpful.

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Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
http://www.lulu.com/content/paperba...an-form/8075185
http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
NAR #54895 SR

Neat idea! thanks for sharing! OL JR

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The X-87B Cruise Basselope-- THE Ultimate Weapon in the arsenal of Homeland Security and only $52 million per round!

You're welcome. I got thinking about laminated card stock fins again after looking at pictures of the French Belier and Indian RH-200 sounding rockets and going "hmmm..."--those ruminations have just made Semroc a little bit richer. :-)

__________________
Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
http://www.lulu.com/content/paperba...an-form/8075185
http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
NAR #54895 SR

Aerospace Speciality Products uses sheet styrene for fin stock in its MicroMaxx scale kits. While building (still not completed) a larger scale Sandia Sandhawk I learned that the actual Sandhawk's fins were quite thin - just over an inch thick at the root and a half-inch thick at the tip edge, so making 1/6-scale fins (for a 2" diameter Sandhawk) that were true to scale and yet sufficiently stiff was a bit of a challenge. ASP's Micro Sandhawk is 1/46 scale, and so even if one succeeded in making fins that were true to scale, the taper in thickness from root to tip (not to mention the knife-edge bevel on the leading edge) would be so small as to be essentially imperceptible. Using 0.020" styrene sheet yields fins that are "close enough" to scale. Sheet styrene is also easy (or at least easier) to hand-cut into an exact shape than balsa or basswood.

The only problem that I encountered with the material was that the solvents in spray paint softened it considerably; the fins became downright floppy after I sprayed them. They regained their stiffness after the paint cured and the solvents evaporated, but I had to be careful to keep them from acquiring warps during the process. I didn't have this problem to quite the same extent with the thicker styrene that was used in my Micro Jayhawk. Still, I would suggest brush painting the fins if you use thin styrene sheet for them.

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SAM # 0011

Laminating layers of card stock together to build up a shape is a standard cardmodeling technique, and I applaud your highlighting of it. If anyone wants to really develop their craftsmanship skills and greatly add to their model-building bag of tricks, they should give cardmodeling a try. A good place to start is with any of Eric Truax's designs, if he still has them posted anywhere. Otherwise, you can build a really nice Mercury-Redstone without too much effort by using the free design from Delta 7 Studios. (Most of Delta 7's designs are for sale, but the site does provide a few plans, including the M-R, for free.) To really develop your skills and learn really advanced techniques, start working on some of the Currell Graphics designs; they can all be downloaded fro free. I spend several hours each night for almost a month building a SpaceShipOne, but the experience was well worth it. (Someday, someday, I'll take on the 30" tall Soviet N-1...) The great thing about cardmodeling is that if you screw up a part, you can just print out another pattern and try again. The cost may be negligible, but my God, what you learn in the process is priceless.

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SAM # 0011

Thank you for posting those links! They are somewhat reminiscent of the old Gulf Oil card stock Apollo Lunar Module models that were given away at their filling stations back in the day (although they were designed for "tongue-in-slot" assembly without glue).

__________________
Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
http://www.lulu.com/content/paperba...an-form/8075185
http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
NAR #54895 SR

I still have a couple of those!