SO, lets get down to this build...
We start off by modifying the notched centering rings. Cut the ring mod guides from the wrap sheet very carefully with a sharp hobby knife. These get glued with white glue to the notched centering rings, aligned very carefully, and set aside to dry. Later we'll notch the centering rings using a sharp hobby knife, according to the instructions. These notches will hold the "booster engine spoof tubes".
Next, we cut some "poly-coated Popielium" string off the parachute shroud line bundle according to the instructions. These bits of string get glued to the ends of the engine spoof tubes. The spoof tubes themselves are from the BT-5 tube in the kit, which you have to cut in half. I applied a tiny daub of white glue to the end of the string and the end of the tube, and then clamped the end of the thread about 3/32 inch up from the bottom edge of the tube with smooth-jawed hemostat clamps. Set these aside to dry.
Once the thread is securely glued to the end of the tubes, I applied a decent layer of white glue to the bottom 3/8 inch of each tube, and then carefully wrap the string around the tube, with about 3/32 inch (little less than 1/16) between each wrap-- these are the engine bell "hat bands" which strengthen the outboard booster engine nozzles on the real Atlas. I apply a little more white glue on top, and then going around the nozzle the same direction I wound the string, rub the glue into the string and onto the tube, securing everything in place. If the wraps aren't evenly spaced, go ahead and space them evenly now, using a fingernail or the back of the hobby knife blade-- the more evenly spaced and smooth they are, the better the rocket will look later on. You'll probably have to hold the end of the string down for a few seconds until the glue tacks up a bit to keep it laying flat and the hatbands wound tightly around the "nozzle" (tube). Once you're satisfied and everything's pretty well tacked itself in place, set them aside to dry.
Next, we glue the two notched centering rings to the BT-20 motor tube. Put a vertical line down the tube with your angle (or doorjamb method if you're still doing it that way-- and for pity's sake, get some cheap aluminum angle at the hardware store next time you're in there! LOL). The centering rings have a small "index notch" you cut in the back of the ring according to the ring mod guides you glued over the ring... (of course by this time you should also have carefully cut out the two 'half moons' on either side of each ring-- if you haven't done that, do it now before gluing the rings up!). One ring is marked "upper" and the other "lower"... they go on basically with the "upper" notched ring in the middle, and the "lower" one on bottom. CAREFULLY align the "index notches" (centered between the large "half moon" notches next to the motor tube) with the reference line you drew on the motor tube. The rings have to be indexed as close to perfectly as possible with this line, or the rocket will roll in flight later on, since the motor spoof tube alignment is determined by the half moon notches in the rings, and the Flamefins go into the engine spoof tubes for flight-- and the spoof tubes are aligned to the motor tube by the rings, and you want everything parallel and aligned. Glue the rings on with a dab of white glue, and once you're comfortable that everything is aligned properly, fillet the rings with more white glue.
Next, the spoof tubes are glued on. I actually jumped steps a bit and went ahead and installed the motor hook first per the instructions. Cut the reinforcement band, glue it in place with white glue, install the motor hook, put a drop of CA on the upper end/tube slit to harden the motor tube a bit, wrap tape around the motor hook, and then glue in the motor block in the front of the tube ahead of the motor hook. Check the alignment and fit of the spoof tubes in the centering ring "half moon" notches, and do a little fine sanding or filing to get a good fit... I found that I had to widen the notches slightly on mine, and sanded the front notch on one side and the back ring notch on the other side to correct for a tiny misalignment in the rings... To check the alignment, hold the spoof tube in the half moon notches with one finger, and while looking past the tubes at a fairly dark background, carefully roll the motor tube to bring the visible edges of the spoof tube and the motor tube together... the spoof tube edge should completely "eclipse" or hide the edge of the motor tube... any misalignment will be visible as a small wedge-shaped bit of the motor tube still visible. A tiny bit of sanding is all that's usually needed to bring everything into virtually perfect alignment if you got the centering rings "keyed" to the reference line on the motor tube correctly. Once you're satisfied with the fit, go ahead and glue the spoof tubes to the rings, using white glue, and the fillet them. They are supposed to overhang the back of the rear centering ring by 9/16 inch, but I gave them a little bit more, because looking at the Atlas-Agena I did last year, I think they look a little better a bit further aft (and I remember from the Atlas-Agena having to fiddle with the upper end of the spoof tubes a bit because they were hitting the insides of the fairings when it was time to glue them on).
Fillet everything and set it aside to dry.
More Later! OL JR
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