Art Applewhite 24mm Helix Build Thread

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JSW

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Searched and didn’t find any build threads for any of the Art Applewhite Helix’s? Figured I’d document my first build of a monocopter. Also is my first build thread.

Plans at: https://www.artapplewhite.com/free/helix/Free 24mm Helix Instructions.pdf

I’ve used Art’s free plans to build several saucers. They are super detailed oriented and well thought out. I intend to follow the directions as closely as I can – especially since monocopters are new to me and feels like a potential for more danger than an everyday rocket if not done correctly?
 
I sourced the LOC body tube from LOC. The other items I either already had or could get at the local hobby shop.

Cut the LOC body tube to size (3-7/8”).

Printed out the main tube template at actual size (100%) but the paper dimensions did not match the dimensions of the LOC main tube. The template print was only 3-3/4" wide vs. main tube is cut to 3-7/8" (3.875”) wide. Also, the circumference of the main tube was about 0.15" more than the length of the template. I think probably a printer difference or other printing problem? I did some quick math and determined to print at 103.33% so that the printout would match the tube's circumference and width.

When cutting out the template, I left a tab on one end to make it easier to wrap and line up. Put down a super thin layer of white glue on the main tube, laid the template down and aligned it. Once it was dry, I trimmed the tab off. (Maybe next time,... use spray adhesive so that I can pull the paper template off?)

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Followed the directions for cutting out the motor, launch lug, and balance beam openings on the main tube. The Launch Lug and Balance Beam labels (L, B respectively) were inside the template’s hexagons that would be cut out. To dummy proof it for myself I wrote the label (L, B) outside the cutout area so there was no question when the holes were cut. (Turns out the hole sizes are slightly different, so maybe not necessary.) Used a small thin craft utility knife with brand new blades. Plunged knife point into each segment of the octagon. Worked pretty well.

My cutout for the motor mount opening was too small. I had to sand the opening to make sure I could get the BT-50 motor mount in without warping it. It was really useful to have a spent E12 casing for sanding, and also help protect the BT-50 as I test fit it.
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Cut the launch lug and balance beam to size. Rounded the ends of the balance beam the same amount.

Marked the center of the launch lug and balance beam. The outside diameter of the LOC main tube is 42mm so I also put a mark at 22mm on each side of center so I could tell when the lug and beam were centered. Here is a picture after the balance beam (after it had been glued) showing the extra markings.

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The 1/8” thick basswood wing was cut from a wider piece to the final dimensions of 18” x 1 5/8” wide x 8” long. I used the “factory cut” edge as the “forward facing” edge,… assuming it would be truer than my manually cut edge. Lightly sanded all edges to round them a bit.

Checked the fit against the main tube inner diameter and then trimmed about 1/16” from the inside 1” of the end of wing slightly to fit the main tube. (I may have trimmed a bit too much as the main tube did not deform as the instructions suggested.) Also adjusted the depth to make sure it met up with the balance beam.

Ready to glue.

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Instructions say to use white glue everywhere. Glued everything in place with white glue EXCEPT the wing. Worried the wing would be the first thing that might dangerously fail - so instead of white glue I used a small amount of epoxy to glue it to both the main tube and the balance beam. I considered wrapping a strip of fiberglass on the inner 1” end of the wing around the balance bar, but opted against. Figured Art had already thought this through using white glue,… I probably shouldn’t have used epoxy,… but surely strong enough.

Checking that the wing seems to line up pretty good with the main tube.

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Still to do:
  • I think I’m going to put some CA to seal the ends of the launch lug and motor mount tubes.
  • Paint. The instructions say to add a thin layer of paint if desired. I'd like to seal everything first and then paint. Maybe superglue to seal the paper that is still on the main tube. And seal the wood parts with some sort of light sealer. Still deciding. Will that screw up the balance?
  • Build a launch stand so I can test it out before the next club launch.
  • Fly it.
 
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This is great. Thank you for posting.

I think your addition of a tab is a great suggestion. And I also think using epoxy instead of white glue is a also a good idea.

Looking forward to flight pix.

Curtis
 
Exactly as I was finishing the AA 24mm helix monocopter,.... the latest Sport Rocketry came out with an article by Curtis Heisey on the Revival of the Monocopter. Decided to build the 3D monocopter. And then since I already the materials for it,... also built a 24mm bi-copter (knockoff of AA 24mm double helix).

Launched them all last Saturday. The copter sound and smoke rings produced were pretty impressive. Cool autorotation. Added plus was that we had wind shift on us,... some rockets lost,... monocopters were fine!
 
For years I've SO wanted to build one if these since I love oddrocs. Thanks for posting!
I like the oddrocs too,... mainly because you can use a big engine AND not be worried you won't see it again.

I'd recommend building one. The copter sound got a big reaction from folks.

The easiest build out of all of these was the one in the Sport Rocketry article, the Revival of the Monocopter. I have never 3d printed before, so I sent the 2 STL files (1 wing and 1 rotor) to https://craftcloud3d.com/. Quick turnaround. Ended up being about $7 per part plus $5 shipping. Assembly requires epoxy and a motor tube. Oh, and needed to go to Home Depot for a 1/4" threaded rod and 6 nuts.
 
Joel and I have been exchanging emails. The 3d printed monocopter is heavy ... doesn't go as high and spins a while on the launch pin, which can be impressive in the own right. But talking to Joel inspired me to design a "hybid" knock-off of Art's Helix. I'm always a fan of using 3d printing where it makes sense and traditional parts where it makes sense. The hybrid design that I arrived with uses a 3d printed motor mount shaped like a body tube, but it has holes for the balance arm, lunch rail, and a slot for the fin, which I used laser cut 3mm ply.
 

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Here is flight. I'll post the stl after LDRS.
 

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