Brief:
180% upscale of the classic Estes Astron Star Blazer (K-31) using BT-55 (1.325") and parts from the spare parts box.

Construction:
The parts list:

• BT-55 11 5/8" long
• BT-55 4" long
• PNC-55 (5 3/8" long)
• balsa sheet 1/8" x 4" x 36"
• strip basswood 1/8" x 3/16"
• JT-55 tube coupler
• block balsa to carve canopy
• BT-20 3" long
• 2 AR-2055
• EH-2 engine holder
• AR-520 engine block
• 18" parachute
• screw eye
• elastic shock cord
• shock cord mount of your choice

Estes rated the original Star Blazer as a Skill Level 3, which I feel is accurate based on the curves of the fins, the long, thin root extensions, the cockpit canopy that is supposed to be carved from a block of balsa, and the 4-color paint scheme. I decided on BT-55 and after downloading the instructions and patterns from JimZ and making correctly sized patterns on a photocopier, I began construction. I decided on a suitably shaped plastic nose cone from a designers special or nose cone pack. It may not exactly replicate the original BNC-20N from the kit, but it works for me. I suppose I could have special ordered a near clone from BMS, but I opted for what I had on hand. I decided on an 18mm motor mount to keep flights on the (relatively) cheap. Like the original, the body tube separates behind the canopy. Rather than using a relatively pricey balsa nose block, I scratchbuilt a nose block from the JT-55 tube coupler and some scrap 1/8" balsa. I strengthened the lower end with a cardstock centering ring for the recovery system screw eye to attach to. I traced the inside diameter of the JT-55 on the balsa and cut it out, securing it inside the JT-55 with a good fillet of yellow glue. I then glued the cardstock centering ring to the balsa and cleaned it up to ensure a smooth fit in the body tube.

I secured the nose cone in place to the short length of body tube the canopy will be glued to. The 4 inch payload section is non-functional. Its only purpose is a place to glue the canopy to.

For the fins, I first traced the pattern onto 0.040" sheet styrene and carefully cut that out, being careful to preserve the curvature of the pattern. This would serve as a guide to help me cut the graceful fins from a 4” wide piece of 1/8” balsa. These are big fins! I used 1/8” strip basswood for the root extensions, thinking they would stand up to finishing and handling better than balsa. Then I started thinking about how to tackle the carved cockpit canopy. My first attempt didn't work out well. I selected a piece of square balsa stock cut it in half lengthwise on the diagonal (corner to corner) and traced the basic kite-shaped pattern as indicated in the original instructions downloaded from JimZ. Then I wrapped a piece of coarse sandpaper around a length of BT-55 and started sanding longitudinally. Before too long I was creating a dusty mess. Instead of getting the desired results, I realized I was sanding off course... The resulting cavity was drifting to one side as I sanded. I shelved that idea and decided on getting a larger block of balsa. Before cutting it in half, I chucked a 1.25” spade bit in my drill press and drilled a lengthwise hole down through the center of the balsa block. Then I cut the block in half as before. Now at least I had a cavity to start with, even though it was a bit smaller in diameter than a BT-55. After laying out the kite pattern and cutting off the excess balsa, I started sanding on the body tube again. This time my efforts were working as planned. I was getting a piece of balsa that would conform nicely to the diameter of the BT-55. Satisfied with that effort, the next task was to shape the canopy. Try as I might, I just couldn't (or didn't want to) replicate the relatively complex shape of the original. I decided on a fairly simple canoe-shaped design that would probably pass for a canopy once painted.

Once the fins and root extensions were attached and dry, I glued the canopy to the tube and used Fix-It epoxy clay to blend the canopy to the tube as best I could. During this time I was realizing my finishing skills needed much improvement. I broke out my 8-year old pint can of Sanding Sealer and started applying. I used some Fix-It to fill some shrinkage holes in the yellow glue fin fillets, which worked quite well.

Finishing:
After sealing and primer, I painted the red/white/blue scheme shown in the early Estes catalogs. The canopy is gloss black. I don't have any decals for the Star Blazer yet. I might try Tango Papa. Engine selection will be C6-5 and recovery by 18” chute.

CONs: fairly complex masking required to get good separation between the body tube and fins/fin fairings, 3-color pattern on fins, and isolating the black on the canopy.

Flight:
First flight was conducted at SSS "SpringBlast" in April 2007 on an Estes C6-5. Good motor for this rocket given the 3.5oz weight. Nice straight boost with successful chute deployment and recovery.

Recovery:
Nothing unusual to report.

Summary:
PROs: Nice challenging build of an Estes classic but on a slightly larger scale. Tests your skills at cutting curved fins, aligning long, skinny fins, shaping a block of balsa into a canopy, and fairly complex masking and painting. Nothing the experienced builder can't tackle successfully.

CONs: Getting the canopy shaped correctly is probably as difficult as on the original. Use your thinker and come up with a workable solution like I did.