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- Nov 29, 2020
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Next project is 3" diameter scratch-built Nike Smoke. I've been experimenting with 3D printed airframe parts (nosecones and fins). The Nike Smoke's long nosecone and thick, airfoiled fins seemed like a fun challenge. I'm not really a scale modeler so that's not the intent of this project. Regardless, I have endeavored to adhere as closely as possible to the dimensions recorded by Harry Stine without getting too caught up in any of the finer details. I've recently come to appreciate the minimalism of the Nike Smoke design, but I am tempted to add a tail cone to it (it really seems to want one). We'll see what happens.
The body tube and motor mount will just be LOC cardboard tubes and the motor mount centering rings standard plywood. The nosecone, avionics trays, and fins will primarily be 3D printed. I'm still working out the weights of the various 3D printed parts.
The nosecone will be printed in 3 parts due to print volume limitations. The nose tip will be printed solid. The mid section and base/shoulder are mostly hollow tubes so are technically printed solid as well. The parts will be epoxied together and then covered with laminating epoxy and sanded smooth. An M4 threaded rod will be epoxied into the nose tip to secure the avionics tray / bulkhead and act as the recovery anchor.
For the fins, I plan to print two outside layers to create the thick airfoil. These will be laminated to a 1/16" G10 fiberglass interlayer. I'll drill a grid of holes in the interlayer to promote epoxy adhesion "through" all three layers. Each assembly will be covered in laminating epoxy and sanded smooth. The G10 interlayer includes the TTW mounting tab.
The avionics package will include redundant Eggtimer Quantum altimeters and an Eggfinder Mini GPS tracker. The bulkhead and avionics tray are one piece. An M5 eye nut (recovery anchor point) holds the whole thing closed (and can be unscrewed for access to the avionics compartment).
Depending on how the 3D printed part weights shake out, she should be able to fly on a pretty wide range of motors. The solid printed nose tip, threaded rod, and nosecone avionics compartment should push the CG forward and the sizeable fins keep the CP fairly aft.
The body tube and motor mount will just be LOC cardboard tubes and the motor mount centering rings standard plywood. The nosecone, avionics trays, and fins will primarily be 3D printed. I'm still working out the weights of the various 3D printed parts.
The nosecone will be printed in 3 parts due to print volume limitations. The nose tip will be printed solid. The mid section and base/shoulder are mostly hollow tubes so are technically printed solid as well. The parts will be epoxied together and then covered with laminating epoxy and sanded smooth. An M4 threaded rod will be epoxied into the nose tip to secure the avionics tray / bulkhead and act as the recovery anchor.
For the fins, I plan to print two outside layers to create the thick airfoil. These will be laminated to a 1/16" G10 fiberglass interlayer. I'll drill a grid of holes in the interlayer to promote epoxy adhesion "through" all three layers. Each assembly will be covered in laminating epoxy and sanded smooth. The G10 interlayer includes the TTW mounting tab.
The avionics package will include redundant Eggtimer Quantum altimeters and an Eggfinder Mini GPS tracker. The bulkhead and avionics tray are one piece. An M5 eye nut (recovery anchor point) holds the whole thing closed (and can be unscrewed for access to the avionics compartment).
Depending on how the 3D printed part weights shake out, she should be able to fly on a pretty wide range of motors. The solid printed nose tip, threaded rod, and nosecone avionics compartment should push the CG forward and the sizeable fins keep the CP fairly aft.
