I was hoping to get out for a launch today, but the forecast is a windy one, so I'm working on some builds.
I've been finishing a family trio of Icarus clones, so haven't had quite as much time for Cassy as I had hoped. Luckily, she's not the jealous type.
Since last report, here's what I've done:
1. On the lower section with fins, I carefully marked off three points on the upper edge of that piece of BT50, marking the midway point between each of the fin lines. The dowel supports need to be glued midway between the fins, and these marks will be the genesis of some mounting lines. At first I wasn't sure what the best way to mark these was... eventually I took a piece of paper and wrapped it around the body tube, marking two of the existing three fin lines onto the paper. Then I folded the paper such that these two tick marks lined up, and the crease was smack in the middle. Then, having a template for where the middle point was, I put the paper back on the tube, lined it up, and transferred the crease-located mark to the BT50. rotate tube, repeat two more times.
2. Then I carefully glued (with Titebond II) all of the BT50 sections to the BT20/centering ring assemblies. The forward two are generic, but the aft section with fins I put on such that the motor hook aligns with the centerline between two of the fins. Not necessary, but makes it look better to me.
3. While that stuff was drying I went to work on the dowel/dowel support assemblies. I sealed the balsa with CA (I had previously soaked in some wood glue onto the root edges). Rubbed on some CWF, let dry, sanded smooth.
4. By this time the main rocket assembly had dried, so I extended those tick marks on the BT50 in between the fins, to provide mounting lines for the dowel supports. I extended them all the way onto the forward BT50, to mark where the dowels should mate to the tubes up front.
5. Those of you who are familiar with my build threads know that I hate to attach fins (or finlike structures) without a fin jig of some sort. I'm just not that good with my hands. But for this situation I sucked it up. Using standard double-glue technique, I successfully mounted the fins one by one, holding at correct position and angle until the bond was strong enough. This was a little bit easier than usual for me because the dowels extend forward quite a ways, and lining them up with the marks on the BT50 up there was an aid to making sure they were on straight relative to the tube.
6. I got my SEMROC discs in; I glued these to the fins at the appropriate spots. On the original model this would have significantly strengthened the joint where the fin extensions meet the fins. On mine, I not only had a wood glue bond there, but also papered over and soaked with CA, so for me the discs are more decorative than anything else. I scuffed up the CA papered surface, and used wood glue to stick them on. I've found as long as CA-impregnated paper is sufficiently scuffed, you can get a decent bond with carpenter's glue.
7. I also used some medium thick CA on the inside of the ringfin. Just swabbed it around and then after dry smoothed it with some 220 grit paper. I'm thinking this will make a nice smooth surface in there to aid bonding of some trim monokote, which I plan to use on the inside of the ring fin.
OK, enough talk, here are some pictures:
Overall view:
Close ups:
I need to sand the forward and back dowel ends to even them up (there's some slight variability, to my eye), then glue down the forward dowel ends. At first, I thought I had the dowel support angle wrong since the tips don't touch the body tube. But reading the instructions again, I see you are supposed to bend them down and hold with tape while the glue dries. The bend actually imparts an extra nice touch visually, I think... I held down the dowels as a test. Looks nice.
At the aft end, I need to put on the discs from SEMROC but I have some special thoughts on this so I'm holding off for now.
I also need to put a launch lug on... it will go against one of the dowel supports.
I'm pleased by how it's coming together.
I've been finishing a family trio of Icarus clones, so haven't had quite as much time for Cassy as I had hoped. Luckily, she's not the jealous type.
Since last report, here's what I've done:
1. On the lower section with fins, I carefully marked off three points on the upper edge of that piece of BT50, marking the midway point between each of the fin lines. The dowel supports need to be glued midway between the fins, and these marks will be the genesis of some mounting lines. At first I wasn't sure what the best way to mark these was... eventually I took a piece of paper and wrapped it around the body tube, marking two of the existing three fin lines onto the paper. Then I folded the paper such that these two tick marks lined up, and the crease was smack in the middle. Then, having a template for where the middle point was, I put the paper back on the tube, lined it up, and transferred the crease-located mark to the BT50. rotate tube, repeat two more times.
2. Then I carefully glued (with Titebond II) all of the BT50 sections to the BT20/centering ring assemblies. The forward two are generic, but the aft section with fins I put on such that the motor hook aligns with the centerline between two of the fins. Not necessary, but makes it look better to me.
3. While that stuff was drying I went to work on the dowel/dowel support assemblies. I sealed the balsa with CA (I had previously soaked in some wood glue onto the root edges). Rubbed on some CWF, let dry, sanded smooth.
4. By this time the main rocket assembly had dried, so I extended those tick marks on the BT50 in between the fins, to provide mounting lines for the dowel supports. I extended them all the way onto the forward BT50, to mark where the dowels should mate to the tubes up front.
5. Those of you who are familiar with my build threads know that I hate to attach fins (or finlike structures) without a fin jig of some sort. I'm just not that good with my hands. But for this situation I sucked it up. Using standard double-glue technique, I successfully mounted the fins one by one, holding at correct position and angle until the bond was strong enough. This was a little bit easier than usual for me because the dowels extend forward quite a ways, and lining them up with the marks on the BT50 up there was an aid to making sure they were on straight relative to the tube.
6. I got my SEMROC discs in; I glued these to the fins at the appropriate spots. On the original model this would have significantly strengthened the joint where the fin extensions meet the fins. On mine, I not only had a wood glue bond there, but also papered over and soaked with CA, so for me the discs are more decorative than anything else. I scuffed up the CA papered surface, and used wood glue to stick them on. I've found as long as CA-impregnated paper is sufficiently scuffed, you can get a decent bond with carpenter's glue.
7. I also used some medium thick CA on the inside of the ringfin. Just swabbed it around and then after dry smoothed it with some 220 grit paper. I'm thinking this will make a nice smooth surface in there to aid bonding of some trim monokote, which I plan to use on the inside of the ring fin.
OK, enough talk, here are some pictures:
Overall view:
Close ups:
I need to sand the forward and back dowel ends to even them up (there's some slight variability, to my eye), then glue down the forward dowel ends. At first, I thought I had the dowel support angle wrong since the tips don't touch the body tube. But reading the instructions again, I see you are supposed to bend them down and hold with tape while the glue dries. The bend actually imparts an extra nice touch visually, I think... I held down the dowels as a test. Looks nice.
At the aft end, I need to put on the discs from SEMROC but I have some special thoughts on this so I'm holding off for now.
I also need to put a launch lug on... it will go against one of the dowel supports.
I'm pleased by how it's coming together.
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Good luck with the launch!!
