The Rotating Ring.

0.5 m2 front , 0.5 m2 side , 3.5 m2 front , 3.5 m2 side , both
14-02-1998, estimated wind just above 1 beaufort.

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Instructions: (photo's available)
  1. Define the radius & number of cells you want. Remember the diameter = 2 x radius.
    Use this JavaScript to calculate your rotor up to an outside diameter of 800 cm, 204 cells and 22 measures. Or this JavaScript to calculate your rotor up to an outside diameter of 2000 cm, 500 cells and 92 measures.
  2. ALL sizes are without hem. Add 5 mm on left and right side of the pattern.
  3. Transfer the pattern to a piece of wood. Do the fretwork carefull.
    Use the wooden pattern to cut the Ripstop Nylon.
  4. Before you cut: think about the rotors turning direction (left or right) and which side of the fabric should be on the in/out-side.
  5. Stop sewing at the indicated length. Add at this stop 2 cm biasband, used as reinforcement. See photo's.
  6. Use biasband for the inner (red) and outer (green)cirkel.
    While sewing the biasband on the outer cirkel all green lines form one straigth line without gap (are aligned). Put the lower part of the next flap on the higher part of the current flap. The bridle eye's are also made of biasband but you could also use 4-6 (folded) layers of fabric.
  7. The bridle line A is about the (2 or 3 x "arc length"). The bridle lines B is ( "One Bridle" - 0.5 x A ).
  8. For the 3.5 m2 version a third bridle C is used, simulair to A, attached to the B eye's. The C eye's are attached to an alloy disk connected the swivel, see photo. The diameter of the alloy disk is 8 cm and it is 4 mm thick.
  9. Used bridle lines: 11 kg twisted nylon for the 0.5 m2 version.
    25 kg braided dacron for A, B and 50 kg dacron for C for the 3.5 m2 version.
    On the photo you see 100 kg terylene for C because I did not have 50 kg dacron at the time. The required strength depends on the size of the rotor and the number of bridle eyes used. Unfortunatly the front view photo of the 3.5 m2 versions shows terylene lines twisted.
  10. Use a super smooth swivel, preferable with sealed ballbearing.
  11. If you have problems with the swivel (fails to turn) then shorten the bridle line B.
  12. Check the photo's.
    The 0.5 m2 (projected, 50 cm OutsideRadius, 30 cm InnerRadius, 20 cm InsideRadius, 24 cells) version pulls about 10 kg at 5 Beaufort. The 3.5 m2 (projected, 200 cm OutsideRadius, 170 cm InnerRadius, 30 cm InsideRadius, 96 cells) version pulled my car (brakes off) on the beach at 5 Beaufort.

The Pattern.

The BridleEye.

The Bridle.