Nike Smoke Scratch Build with 3D Printed Parts

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Kane

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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.
Nike Smoke - Frame 1.jpg


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.
Nike Smoke - Frame 2.jpg

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.
Nike Smoke - Frame 3.jpg


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).

Nike Smoke - Frame 4.jpg


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.
 
Consider sharing the STL files once you get it built. People would love to build it.
 
Consider sharing the STL files once you get it built. People would love to build it.
Will do. Made some slight modifications - including sending the nose cone tip out to be CNC'd aluminum. I'm sure there will be some more iterations as I print, assemble, weigh, and adjust for stability.
 
1000009725.jpg
Just arrived today from JLCPCB. Aluminum nose cone tip. Anodized and threaded for an M5 threaded rod to connect it to the rest of the nose cone and the avionics bay.
 
Consider sharing the STL files once you get it built. People would love to build it.
Agree on this. I found a 3" Nike nose cone file somewhere online and printed it but holy cow the geometry that they exported it with was horrendous, very low-poly for most of the lower section with a few high poly smooth areas.
 
Got the bottom section of the nose cone printed. Next I'll epoxy the base and mid section together and then coat with laminating epoxy to smooth.
b27cd42d-b5ba-452b-833a-0bc618323b2f-1_all_40600.jpg
1000009860.jpg
 
cool..
I see one point of concern..
Your 1/16 G10 inner layer is pretty lite weight. I realize you're adding an other layers of airfoil..which adds some thickness to the fins. But 80% of the workload will be done by that 1/16 G10 through the wall.

Nike smoke fin shape is not the best anti flutter profiles (short root to span ratio)

I did not see what size motor tube you're going with ..if it's 29mm and H reloads...it will probably be OK..

still a cool project.

Tony
 
cool..
I see one point of concern..
Your 1/16 G10 inner layer is pretty lite weight. I realize you're adding an other layers of airfoil..which adds some thickness to the fins. But 80% of the workload will be done by that 1/16 G10 through the wall.

Nike smoke fin shape is not the best anti flutter profiles (short root to span ratio)

I did not see what size motor tube you're going with ..if it's 29mm and H reloads...it will probably be OK..

still a cool project.

Tony
I am anticipating some added resistance to flutter from the printed airfoil layers (printing on a diagonal so none of the layers are orthogonal to the flight vector and the lamination will add some stiffness), but that's not calculable (at least, not by me) so I've left it out of the flutter calcs. I'm glad you pointed this out though. I do actually check flutter for all my scratch builds and did so for this one. However, after reading your comment I went back and looked at my spreadsheet and realized I hadn't considered flying anything larger than an I motor. I had originally started this project thinking it would just fly H and I motors. Upon further reflection, a J340M or J340W could be a killer flight. Those motors definitely put the speeds above what that 1/16" G10 can handle. Looks like bumping the thickness up to 3/32" will do the trick. This bumps the "safe" velocity up to 990 ft/s which is about the speed predicted on a J340M.

Thanks for the heads up!
 
Probably not necessary unless one wanted to push it over mach (even then, probably not necessary). I've been itching to try this service and it was relatively inexpensive.
I have a separate configuration that can be printed that's omits the aluminum tip for a printed one.
 
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