My initial version of a Darwin Wind Collector for a 4" PVC pipe sized so all the parts can be printed within the 200x200 limit of most printers. These can be used as air collector for enclosed spaces or as a way to drive a small wind generator (old PC fan) as shown in this video: https://www.youtube.com/watch?v=Js8if1YmptU

Print count: Collar: 1 Lid: 1 Wedge: 6

The section view shows the position of the fins vs the inside of the pipe and the profile drawing shows the dimensions of the fins themselves. This was produced with the inner fin profile.

Note: The only pipe specific dimension is the Inner Diameter of the Collar that needs to fit over the Outer Diameter of the pipe you are using so to use a 3" PVC pipe with 3.5" OD set your scale factor to 3.5/4.5 = .78 or 78%

UPDATE: I printed a version for 3" pvc (3.5in OD) by scaling each part by 78% the collar notches were too tight so I made a specific 3.5in version of the collar.

UPDATE 2: I've added two new lid designs. One with baffles to better direct captured air down the pipe and one with baffle slots so the baffles themselves can be made of bent cardboard - saving on print time and plastic.

UPDATE 3: Stayed up super late and designed a serpentine generator to go with the wind collector based off of RMS's mag-lev squirrel cage design. I've included a slat just for dimensions but they can just as easily made from flat stock.

UPDATE 4: Added the "deep well" version of the Rotor - see cross section view for details - the original rotor will likely bind up the bearings.

UPDATE 5: Added new Stater design with electronics bays and wire vias

UPDATE 6: Added Stater Lid so the coil and electronics can be sealed against the weather.

Future improvements:

Blunt the trailing edge of the vent fins so they print more cleanly.

Add "Screw" insert to twist the air flow - might increase flow rate/clean the air - beware the static monster.

Add base that serves to catch dirt and a vent to drive a generator that can charge one or more cell phones.