avets8
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Sooo, I am currently at the end of the design process of a 1/20 or 1/22 (haven't decided yet) scale of the SR-71 Blackbird I plan to launch at NERRF 6.
I have made it on RocSim and it works well. The margin is 1.5ish without the motor(s) and .5ish with the motor(s). That is without any nc weight so I'm planning to add a few ounces of clay to the nc. It probably doesn't matter now but my plan is to launch it twice:
1) Cluster; central G77R and 2x F52T
2) I345-WT
Since the wingspan of the Blackbird is so large, about 32 in including the engines, I plan to fiberglass the fins with 2 oz fiberglass. I'm having determining what material to use for fins. I'm trying to keep it lightweight, 1/4in preferably, and Im trying to steer away from G10 fins. I've already ruled out Birch plywood because of the weight. I was looking at Poplar but I think its pretty close in weight to the Birch. 1/4 aircraft plywood would be the best option right now since its lightweight and durable but cost wise its a little more and I can't seem to find it in big enough sheets that I need. Is there anything I can do to 1/4in (maybe even 1/2in) Balsa to make it stronger before glassing it? I was thinking paper layering it first but I don't know how the fiberglass would hold to the paper. Maybe just glassing balsa would be enough? But I'm not sure. Anyone have any suggestions or feedback on material?
Would any sort of lightweight but dense plastic do the trick if the surface were roughed up? Would the fiberglass grip to plastic?
I will also be using lots of foam and bondo to make the various curved parts and details for this rocket.
Just giving a heads up, I will most likely have more questions along the way....I hope people don't mind
Thanks!
View attachment SR-71 Blackbird internet pictures 1.bmp
View attachment SR-71 Blackbird internet pictures 2.bmp
I have made it on RocSim and it works well. The margin is 1.5ish without the motor(s) and .5ish with the motor(s). That is without any nc weight so I'm planning to add a few ounces of clay to the nc. It probably doesn't matter now but my plan is to launch it twice:
1) Cluster; central G77R and 2x F52T
2) I345-WT
Since the wingspan of the Blackbird is so large, about 32 in including the engines, I plan to fiberglass the fins with 2 oz fiberglass. I'm having determining what material to use for fins. I'm trying to keep it lightweight, 1/4in preferably, and Im trying to steer away from G10 fins. I've already ruled out Birch plywood because of the weight. I was looking at Poplar but I think its pretty close in weight to the Birch. 1/4 aircraft plywood would be the best option right now since its lightweight and durable but cost wise its a little more and I can't seem to find it in big enough sheets that I need. Is there anything I can do to 1/4in (maybe even 1/2in) Balsa to make it stronger before glassing it? I was thinking paper layering it first but I don't know how the fiberglass would hold to the paper. Maybe just glassing balsa would be enough? But I'm not sure. Anyone have any suggestions or feedback on material?
Would any sort of lightweight but dense plastic do the trick if the surface were roughed up? Would the fiberglass grip to plastic?
I will also be using lots of foam and bondo to make the various curved parts and details for this rocket.
Just giving a heads up, I will most likely have more questions along the way....I hope people don't mind
Thanks!
View attachment SR-71 Blackbird internet pictures 1.bmp
View attachment SR-71 Blackbird internet pictures 2.bmp