Nike Smoke Build Log
- Nike Smoke 4”
- Kwik Switch 29/38/54 set
HAMR motor retainer
Fit centering rings to new motor tube. Centering rings are 1/16” too large in inner diameter. With compass, marked circle 1/32” from inner edge. Using 100grit dremel sanding wheel, sanded to mark.
Dry-fit 29mm and 38mm adapter tube centering rings. 38mm adapter centering ring slides easily. No sanding needed. 29mm adapter centering ring is too tight. Using 150 grit sanding paper, sand inner edge of the ring until it is loose enough to get onto the tube without danger of crushing it.
Stabilize rocket body tube ends. Using thin CA glue, painted both ends of body tube. After about an hour, sanded the inside of the tube, then using an x-acto knife, trimmed down the inner edges until the centering rings could be slide out. Dry fitted the motor tube and centering rings inside the rocket body. The rear end of the body tube was scuffed up a bit by this process, so I added more CA, painting 3/8” inside each end of the tube. This dried overnight
More messing with the body tube ends. This time, I applied the dremel to sand the ends of the body tube. Now the centering rings slide inside without damaging the body tube ends.
Fitted the Kwik Switch plastic bits onto the motor tubes. First, I roughed up the outside of the 29mm and 38mm tubes and the inside of the 54mm tube using 60 grit paper. Then I mixed a bit of epoxy and applied it to the tubes, sliding the plastic bits into place, rotating them gently to spread the epoxy around and then sat them on the floor to cure.
Attached the U-bolts to the centering ring and nose cone bulk-head. Using washers next to the wood and nuts outside of those, I tightened things down and then applied a dab of epoxy to each set of threads.
Glued on the adapter tube centering rings. Marking a single spot 1/2” from the rear of each adapter tube, I wrapped a piece of paper around the tube, lining the paper up with the mark and with itself and then drew a pencil line around the tube. Then, I applied a thin layer of epoxy above the pencil line and slid the centering rings onto the tubes, lining the aft end of the centering ring with the pencil mark. I neglected to sand under these rings; they won’t take any load along the rocket axis, so that shouldn’t matter. Even still, poor form.
Glued the middle centering ring to the motor tube. Placed the retaining ring on the end of the motor tube and measured up 7” from that to mark where the middle centering ring should end up. Wrapped paper around the tube to complete the mark. Again, failed to abrade the motor tube with 60-grit paper; a more serious error as this joint will take some load along the axis of the rocket. Spread epoxy just forward of the pencil mark and slid the centering ring up onto the glue. I let that harden for a while with the motor tube standing upright. Then, I turned it over and added new epoxy behind it for a fillet on the aft side.
Messed with the fit of the fins. The fins just barely fit into the body tube slots, so I spent a few minutes working each fin into each slot. Now the fins slide in, although it’s still a very tight fit.
Rounded the inside forward corner of each fin. Because the middle centering ring has an aft fillet, this corner needed to be rounded out. I made sure each fin would fit all the way around the motor tube as I didn’t want to worry about motor tube alignment as it gets installed.
Motor tube installation. This time, I managed to sand the glue surface inside the rocket just forward of the fin slots. I also sanded the area where the forward and aft rings will go, as well as where the fins will attach, figuring it would be easier to do without the motor tube in place. I then spread epoxy along this line, carefully avoiding getting any into the fin slots themselves. I stuck the aft centering ring right at the end of the motor tube and inserted the tube into the body. I lined up the middle centering ring just ahead of the fin slots. It didn’t line up perfectly with all of them, so either the fin slots aren’t lined up right or the centering ring isn’t perpendicular to the body tube. The maximum gap is about 1/32”, so I think epoxy will bridge that. I twisted the centering ring and motor tube to spread out the epoxy evenly, and tried not to push it in too far so that the fillet on the forward side of the ring wouldn’t get pushed away. I then placed the forward centering ring in position and stuck the body on the floor upright so that the epoxy could sag back into position.
Forward centering ring installation. With my long dowel/tape epoxy applicator, I spread a thin layer of epoxy around the inside of the body tube where the forward ring goes. I then spread another slightly thicker ring of glue on the inside of the forward centering ring. Then, I slide the centering ring into place, rotating it to spread the glue evenly. I then stood the rocket on the forward end of the body tube to let the epoxy sag back down onto the rear face of the centering ring. Once the epoxy hardened a bit, I turned the tube back over and used my dowel/tape rig to spread a bunch more epoxy to create a forward fillet inside the body tube on the ring. I spread this out by putting tape on my finger and using that. I probably should have used a glove, but I forgot to get one ready before mixing and applying the epoxy. The fillet turned out fine even so.
Fin installation. Built a jig from two pieces of 3/8” plywood cut in U shapes. Spread a thin layer of epoxy along the root of two fins and a thicker layer along the leading edge where it meets the middle centering ring. Then inserted the fins into the body and pushed them to meet the motor tube. Clamped the fins between the two pieces of plywood to keep them in line with one another. Then did the other pair the same way.
Middle centering ring fillets. Poured gobs of epoxy down onto the middle centering ring with the rocket standing on its nose. Mushed it around with a stick into the corners. It mostly flowed flat across the middle. I think there’s plenty of epoxy in there now.
Interior Fin fillets Laid the body on its side with one fin pointing straight down. Mixed a lot of epoxy and applied it with a stick to all of the up-facing interior corners between the four fins and the body and motor tubes. Two on each fin. Then rotated the body 180° and did the remaining corners. Examining these afterwards showed a few gaps in the fillets. Need to come up with a more reliable way of getting epoxy into that small space. Forming the fillets with the dowel did appear to work though, most of the corners were smoothly filled in.
Rear centering ring and motor retainer Cleaned up the epoxy left from the interior fin fillets (be neater next time, I know it’s hard). Used 60 grit paper on the end of the motor tube and the interior of the body tube where the motor retainer and rear centering ring will rest. Masked the motor retainer everywhere except the surfaces to be glued; getting glue on the threads would be bad. Mixed up JB Weld for this job. Spread JB weld on the motor tube outside, on the body tube inside and on the motor retainer inside. Placed the aft centering ring into the body tube and barely onto the motor tube. Took the motor retainer and pressed it onto the motor tube, driving the centering ring forward. Left the rocket overnight for the JB weld to cure.
Nose cone bulkhead. Wearing a plastic bag on my arm, and a glove on my hand, I stuck the bulkhead inside the nose and made it as flat as I could manage. Then I stuck a piece of blue tape on the inside of the nose just behind the U-bolt to serve as a registration mark. I tried to scribe a line around the bulkhead using a compass, but the nose is small enough that I couldn’t see around my arm. I did get pencil marks on the bulkhead. A better plan might be to guess what the maximum change would be and scribe a clean line from the edge of the bulkhead and then use that as a guide while sanding. In any case, I sanded the bulkhead to fit inside the nose. It worked fairly well, although there were a few spots not perfectly touching the inside of the nose. I then mixed a small amount of epoxy and dipped the bulkhead into it, then inserted it into the nose and wiggled it to spread the epoxy around. I then mixed a larger batch of epoxy and poured it onto the bulkhead and spread it around with my (gloved) finger to form a fillet. That turned out fairly well, actually. The plastic bag + tape + glove even kept the fiberglass off of my skin.
Shock cord setup. I melted the ends of the shock cord to keep it from unravelling, then I tied a bowline in one end, making the loop large enough to pass the knot back through the loop. I then tied the other end to the quick link using two half hitches. Holding each knot tight, I spread a bunch (too much) CA on each one. After cleaning up the excess, I let them cure. Then I stuck the bowline through the u-bolt in the nose, passed the quick-link, the rest of the shock cord and the knot through the loop and pulled it all snug. Now I can attach the quick-link to the u-bolt on the forward centering ring.
Exterior Fin Fillets I started by masking the body and fins about 1/8” from the corner so that the resulting fillets are clean-edged. I also wrapped tape around the body tube to mask the leading and trailing edges of the fins. Then, I mixed up epoxy with talc, about 1/1/1 (epoxy/hardener/talc) to create a fairly thick mixture. Setting the fins at a 45° angle, I filled the upper two fillets using a popsicle stick to make them smooth. Once that pair were set, I rotated the rocket 90°and did another pair. Once both sides of a single fin were filled, I sculpted the fore and aft edges to try and make them pretty too. With all four pairs finished, I removed the tape while the epoxy was still a bit soft and cleaned up a few rough spots on the fore and aft corners. This all went very well, I think and the resulting fillets are smooth and clean.
Bondo on the nose cone seams. Very little hardener to a lot of epoxy — the first batch I made up hardened too quickly. Then a lot of sanding. I spread this with a business card to conform to the shape of the nose; that worked fairly well.
Primer. Several coats. I screwed the motor retainer ring and taped the fore and aft ends of the rocket to prevent overspray. I also taped up the nose, leaving about 1/8” of the joining portion exposed to avoid leaving a white seam when the rocket is put together. I didn’t want to paint the entire joint as it already fits snugly. I bought white primer which matched the fiberglass on the body and nose. I don’t think that was optimal as it made it quite difficult to tell when I had covered everything. Otherwise, one spray can did two coats on all surfaces.
Yellow fins and nose. I figured it would be easier to mask off the fins than to mask off the body, and dark colors cover lighter ones better than the other way around, so I started with the yellow. I left the body unmasked after testing to make sure the blue would cover the yellow in one coat. I sanded the whole rocket with 220 grit paper until it was reasonably smooth. Then, I applied three thin coats of yellow to the nose and fins. I left this to dry overnight.
Blue on the body Masked off the fins using blue tape and printer paper, left the masking on the aft and fore ends alone. Sprayed three light coats over the entire body while it was standing on the aft end. After an hour, I checked and there were a few yellow voids below the fins, so I turned the body over and sprayed those quickly.
Rail guides. Picking the space between two fins opposite the u-bolt in the fore centering ring, I measured up from the bottom and down from the top using a dowel to find the middle of fore and aft centering rings. Then, I found the middle of the space between the fins and used a piece of right-angle aluminum stock to transfer that measurement to the drill sites. I drilled holes with a 1/8” bit, using a piece of tape to keep from drilling too far. I then test-fitted the rail guides. Placing a tiny amount of epoxy in each hole with a toothpick, I drove the rail guides back in. I tested the clearance around the nose and it looks really tight. I suspect the nose is going to get banged up on the rail. I’m hoping the rocket won’t get hung up…
Pressure hole drilling. Measuring up 1/2 way between the upper rail guide and the fore end of the body, and then lining up the drill site with the two rail guides, I drilled a 3/16” hole and cleaned it out as best I could. There is still a bit of paper chaff inside the rocket.