Background: 

While thinking about a NARAM scale bird in the spring, I gave considerable thought about not flying. I had way too much NAR work to do, and I really need to make new molds and forms for the 1/48th scale Atlas I was flying in prior years (2.5" dia).  At the NSL, Ric Gaff flew a 3" dia. Nike Apache made with a tube rolled from posterboard on a single D12 that had the neatest slow flight I'd seen in quite a while.  I decided that I really wanted to replicate that slow liftoff with my NARAM bird, and got the crazed idea that a 3 D12 cluster would be just the thing to do that. I 
re-computed my NARAM-39 bird dimensions using an Excel 97 worksheet, and really didn't like what I saw there. Too big, I thought, so I looked in Rockets of the World for something smaller.  While I'd previously modeled AC-27, Pioneer 10 launch, I chose AC-14 because it offered better flight performance margins. 

RSIM was used to model the flight performance.  Three D12's offer only 57 Nt-sec. of impulse, so weight had to be watched.  I modeled 1 lb and 2 lb birds in a 10 MPH wind.  The 2 lb beast went 220 feet, and pulled a bit over 7 G at liftoff; that's right at the edge of acceptable performance in terms of both altitude and the right scale effect at liftoff, IMHO, so with a 1 lb weight target in mind, off to the workshop we go. 

Construction

I pulled posterboard from my supply, cut the sheets to the proper width for a 4" dia tube, and then painted a thinned Titebond coat along the edges.  I also cut a 1/2" wide strip of posterboard and painted it, too. After drying, I rolled the tube, put in the strip and used a Monokote iron to seal the tube.  The heat creates some reaction in the dried glue, sticking the bits together.  Doing it this way avoided any wrinkles.  To attempt to insure roundness, the heat process was done around a commercial 4" tube, making the bird slightly larger than 4" but hey, it's Sport Scale.... 

I then constructed couplers because the poster board I had came in 28" lengths, and I needed a 40" tube. 

The tube at this point was quite weak and "squishy".  I debated about installing some balsa frames to strengthen it, and round it out, but ultimately added two inch long sections of 4" tube to a BT-50 stuffer. These sections added LOTS of roundness and strength. 

I used my NARAM-37 4" BMS supplied nosecone. 

My corrugations were Bunny standard issue made by vacuforming .020 styrene over Evergreen Models railroad car siding, 1/10" spacing.  Jet or other CA makes quick work of attaching those sections.  For the corrugated interstage adapter, I cut the styrene for the various hatches, etc. 

I cut formers from 1/8" balsa for the conical booster engine farings and glued them to the main 4" tube.  I then cut posterboard patterns for the farings, and attempted dry rolling them to shape. I got lots of wrinkles, so I decided instead to wet roll them.  Using the minimum amount of water to wet the farings, letting it soak in 60-90 seconds before rolling, and then using a dowel to assist, the farings rolled to shape with no noticeable wrinkles.  I let them dry overnight before attaching them to the formers, using the same Titebond techniques I used on the main tube. 

I made engine nozzles from file folders, drafting the transition sections using RocketCAD, an excellent tool well worth the money.  I attached the nozzles to the engine tubes. The nozzles swivel in the real Atlas, but the internals of the engines must be protected from the heat.  So a flexible 
protective covering must be installed around the engines.   I simulated that using   1/4" thick balsa covered with foil, deliberately crinkled to simulate this material, a technique shamelessly stolen from Jay Marsh. 

I made engine mounts from Totally Tubular material, Estes centering rings as engine blocks and engine hooks. 

I cut all the various round "bits", i.e. fuel lines, LOX pipes, Centaur hydrogen vent, etc. from Evergreen and Plastruct tubing.  Go to a hobby shop specializing in railroad stuff to find good supplies of this material.  Evergreen now supplies half-round styrene; it's excellent for farings, 
etc. folks. 

I made the veriner rockets from balsa covered with styrene sheet, with the nozzles being turned Evergreen tubing. 

I made the retrorockets around the upper thrust structure from 3/16" dowels, rounded to shape using my 3/8" drill with three coats of clear dope to seal them. 

All the bits were constructed in advance, mounted on pins, and then sprayed with either Testor's Silver or Krylon Metallic Aluminum.  After drying, I attached them with Jet. 

The instrument pods, i.e. the rectangular farings on the sides of the Atlas, were made from balsa, built up from 1/4" squares and sheet. After shaping, I applied two coats of Elmer's fill and finish then covered them with aluminum foil.  To attach it I used a standard UHU glue stick. I alternated the shiny and dull sides of the foil in sections to simulate the panel lines.  I covered the joints with aluminized mylar.  The pods were attached using Jet. 

The Centaur is covered with four panels that insulate the bird on the ground.  Those panel joints are covered with raised farings. I made those from posterboard attached with full strength Titebond, but they really should have been 1/8" balsa carved to the proper rounded shaped and 
filled.  Didn't have time, guys.... 

The real trouble of the bird came when trying to coordinate the internals. I originally thought to plumb the two outboard engines into the center BT-50 stuffer tube, but basically screwed that up, and after two attempts to hack a solution, I gave up and decided to eject the outboard motors. 
That made me switch to D12-0's for the outboards, and made me install two 6MM tubes to store a streamer for recovery.  Those tubes ended up to be too small; I really should have used 10 or 13MM, and at flight I simply elected to let the booster engines tumble.  The RSO let me get away with that, and I don't think it was too bad.  They tumbled quite nicely and safely. 

Part of my trouble here stemmed from a desire to put different shades of metallic on the nozzles separate from the back end of the Atlas.  To do that, I decided to keep the nozzle and internal ducting separate from the main bird and install it only after painting.  That turned out to complicate things unnecessarily, in retrospect, and next time I'll do it different. 

I also picked up some 1/8" Lexan at Builder's Square for fins.  These fins have been the subject of much interesting debate here about which the Wabbit has been quite amused (grin).  When I peeled the backing off the Lexan, I found out I had accidentally purchased translucent material.  I 
had to switch to .040 clear plastic.  While the plastic is more flexible than Lexan, I don't think it's a bad material to use on finless prototypes. You need to size fins such that they've got relatively low aspect ratios, but if you do that, I don't think flutter will be a problem. 

I sized the fins using VCP, and headed for 1 caliber stability.  To attach the fins, I cut them with tabs, then reinforced the internal mounting area with 1/4" sq. spruce.  After the bird was painted, I cut slots for the fin tabs, inserted them and used Jet to attach them.  This lack of precision caused the first flight drop of 3 out of 4 fins and led to some coning after burnout.  (Long time NAR members might remember my 2nd place AC-27 of NARAM-36 which sported only 2 clear fins and the booster farings, and exhibited similar behavior.) I should have added those farings as fins in VCP to get a more accurate picture of the model's stability. 

At any rate, a better attachment method will have to be developed prior to the next attempt. 

Markings: I'm a firm believer in clear decal stock and laser printers for black markings.  Mine were done in Microsoft Word 97, using an Amarillo USAF font sent to me by Norm Heyen, a fellow NIRA member.  If you go to Altavista, or your favorite search engines, and try searching on "font", you'll find hundreds of sites where you can download fonts.  You should search those sites for a "stencil" font, and find one that fits your needs. Most rockets were marked in such fonts.  If all else fails, I have used Helvetica with convincing results. 

AC-14 sports a small circular marking, which I created using Word's drawing tools.  Turned out perfect, IMHO.  I also made sufficient copies on the single sheet of decal material I had for two other 4" models, so look out next year, guys.... 

The black striping on the bird I created using Monokote.  It didn't work worth a hoot, mainly cuz I don't know how to Monokote worth a darn. I heated the iron too hot, damaging both the white paint and wrinkling the Monokote excessively.  Sigh. 

Summary:

I finished a solid 6th, about 30 points behind Pete Alway's Black Brant X and 30 points ahead of the 7th place finisher.  Pranging the second flight didn't help, but did eliminate the problem of how to transport a large bird, which had arrived in Muncie in pieces, back to Chicago.  For the 60-70 hours I had in the bird, I thought it was a respectable showing, particularly given a LOT of NAR work that had to get done prior to NARAM. 

Thoughts for Next Year:

Given the success of wet rolling the conical booster farings, I initially thought of dropping the Atlas and switching to Soyuz.  I have excellent Russian and Polish 1/50th scale drawings of the bird, and a strong interest in the prototype because it's got such interesting "bits" covering it.  But it's got a LOT of those, and I don't know the bird well at all. Atlas has, IMHO, equally interesting bits, and I know the bird like the back of my hand, having modeled it in various scales since 1993.  I think I'll 
stick with the Atlas, and I kinda liked the AC-14 round.  My thoughts on improving it include: 

• do the internal plumbing right
• attach  the nozzles only after everything is done
• figure out if it's possible to do the booster stage drop; Tom Beach talked me into this on the ride back to Chicago and I think I've figured out how to keep the fins on the main Atlas while dropping the booster
• see if we can stage the Centaur
• roll a two wrap 4" fiberglass tube to get rid of the posterboard seam; weight is the key here; if the fiberglass tube can be made light enough, I'll abandon the posterboard.
• get solid fin attachments prior to painting; masking the fins is preferable to losing them at liftoff
• get the damn parachute out
• remember that this is for fun; those of you heartbroken on my prang should forget it;  I had a blast building and flying AC-14, and the bird, while its life was short, taught me a lot.