CONSTRUCTION ---------------------------------------------------------------------------- 1. Assemble two (2) 18mm motor mounts and one (1) Long "E" 24mm motor mount, using the EH-375 in the long mount. Set aside to dry. 2. Cut two (2) 1/4" diameter holes, 180 degrees apart, into each of the remaining two (2) of the BT-50H tubes, 2" from one end. These will become the boosters. 3. Mark each booster tube for four (4) fins at the opposite end to the holes. Draw three (3) lines lengthwise to the tube at three of the marks to a length of 3", and one line the full length of each booster. Mark the BT-70 for two boosters, 180 degrees apart, from the bottom of the tube, for a length equal to the BT-50H. 4. Glue a BNC-50K into the TOP of each booster tube. Apply glue into the bottom of the booster, to a depth of 2", and insert one (1) 18mm motor mount assembly from step 1, pushing forward until the bottom of the BT-20J is level with the bottom of the booster. Repeat for the other booster, and set aside to dry. 5. Insert the top of the long 24mm motor mount from step 1 into the bottom of the BT-70 for a depth of about 4". Apply a bead of glue about 2" from the bottom of the tube all around the inside, and continue pushing the mount into the BT-70 until the bottom of the mount tube is level with the bottom of the BT-70. Apply a bead of glue around the outside edge of the rear mount ring (where it contacts the BT-70), and likewise to the forward mount ring from the top of the BT-70. Use a glue applicator to do this step. Set aside to dry. 6. Thread the screw eye into the center of one face of the NB-70, carefully reverse-thread the eye out, and force glue into the hole. Rethread the eye into the hole. 7. Mark the NB-70-4 (full length from BMS) at 1" from one end, and draw a line completely around. Apply a layer of glue completely around in this area, and apply another layer of glue inside one end of the BT-70H for a depth of 1". Insert the glue end of the NB-70-4 into this end of the tube, then set aside to dry. 8. Mark the BT-70 at 3", 3.125", 5.875" and 6" from the bottom of the tube. Draw lines completely around the tube at these marks. 9. Mark the BT-70 at 3", 2.875", and 0.125" from the top of the tube. Draw lines completely around the tube at these marks. 10. Cut a body wrap from a sheet of scribed styrene 2.75" tall and 7" long, where the scribing runs parallel to the short dimension. WITHOUT GLUE begin wrapping the styrene around the BT-70 until the wrap overlaps. Mark the wrap at the overlap, and carefully cut to final length. If in doubt, cut slightly oversize and use a sanding block to adjust the fit. Repeat this step for the other wrap. 11. Attach the wraps between the lines drawn in steps 8 and 9, leaving a 0.125" (1/8") area on the top and bottom of each wrap. Use a water-based contact cement to avoid damaging the styrene. 12. Attach a strip of styrene 0.125" wide around the top and bottom of each wrap in the same manner. 13. Cut the four (4) long and four (4) short booster standoffs. Attach the long standoffs to the BT-70, 0.125" to either side of the booster lines, on the bottom side of the lower body wrap. Use the double-glue method found in Stine's Handbook. Attach the short standoffs in the same manner on the top side of the lower wrap. Allow to dry. 14. Attach three fins to each booster using the double-glue method, along the three short lines. Use jigs, angle alignment fixtures, and clamps to hold the fins in place until dry. 15. Attach the boosters to the booster standoffs, aligning the long line on the booster between the standoffs, using the double-glue method. The bottoms of the boosters should be level with the BT-70. Let dry. 16. Attach the two launch lugs to their standoffs using the double-glue method. When dry, attach one to the main body half-way between the two boosters, with the top of the lug/standoff just touching the bottom edge of the lower body wrap. Attach the other lug inline with the first, with the top of the lug/standoff just touching the bottom of the upper wrap. Use the same double-glue method when attaching the lugs to the body. 17. Assemble two (2) 18" diameter parachutes. Attach the shroud lines of each parachute to a swivel. Attach one shock chord to the inside of the main BT-70 body tube at a depth of 4" from the top, using a folded paper mount. When dry, attach the free end of the chord to a swivel. Attach a swivel to each end of the other shock chord. Attach the mounted shock chord to one of the two parachutes. Attach one end of the unmounted chord to the screw eye, and the other end to the remaining parachute. 18. Prime, sand, and finish the model in a color scheme of your choice. The recommended colors are white overall, with black or silver nose cone and black fins. When the color coats have dried, apply a clear gloss coat to the model. 19. The main body motor mount can accept the long "E" motors from Estes, and the boosters use standard 18mm "A", "B", or "C" motors. The ejection charges will vent harmlessly through the two 1/4" holes in the boosters. 20. GO FLY! Copyright © 2003 by Craig McGraw. All Rights Reserved.