telemetry-antenna

// Aircraft telemetry antenna plate
// Consists of a circular base plate 3 inches in diameter and 0.08 inches thick, with a tapered monopole antenna mounted at the top with a base diameter of 0.65 inches and height of 1.36 inches. Also consists of a mounting base and connector at the bottom of the plate. The plate also has 6 countersunk holes at a defined pitch circle diameter.

// Set units
@settings(defaultLengthUnit = in)

// Define parameters
plateThickness = 0.08
plateDia = 3
antennaBaseDia = 0.65
antennaAngle = 95
antennaHeight = 1.36
seatingDia = 0.625
totalHeight = 2.14

boltDiameter = .196
boltPitchCircleDiameter = 2.5

// 2D cross-sectional profile of the part that will later be revolved
antennaCrossSectionSketch = startSketchOn(YZ)
antennaCrossSectionProfile = startProfile(antennaCrossSectionSketch, at = [plateDia / 2, 0])
  |> yLine(length = plateThickness)
  |> xLine(length = -(plateDia - antennaBaseDia) / 2, tag = $seg03)
  |> angledLine(angle = antennaAngle, length = 1.1, tag = $seg01)
  |> tangentialArc(endAbsolute = [0.025, antennaHeight])
  |> xLine(endAbsolute = 0, tag = $seg02)
  |> yLine(length = -totalHeight)
  |> xLine(length = .25)
  |> yLine(length = .05)
  |> angledLine(angle = 45, length = 0.025)
  |> yLine(length = .125)
  |> angledLine(angle = 135, length = 0.025)
  |> yLine(length = .125)
  |> xLine(length = .025)
  |> yLine(length = .025)
  |> xLine(endAbsolute = seatingDia / 2)
  |> yLine(endAbsolute = -0.25)
  |> xLine(endAbsolute = 0.6)
  |> yLine(endAbsolute = 0)
  |> close()

// Revolution about y-axis of earlier profile
antennaCrossSectionRevolve = revolve(antennaCrossSectionProfile, angle = 360, axis = Y)

// Function to create a countersunk hole
fn countersink(@holePosition) {
  startSketchOn(antennaCrossSectionRevolve, face = seg03)
    |> circle(center = holePosition, radius = boltDiameter / 2, tag = $hole01)
    |> extrude(length = -plateThickness)
    |> chamfer(length = 0.04, tags = [hole01])
  return {  }
}

// PCD converted to radius for positioning the holes
r = boltPitchCircleDiameter / 2

// 6 countersunk holes using the countersink function
countersink([r, 0]) // 0 °
countersink([r * 0.5, r * 0.8660254]) // 60 °
countersink([-r * 0.5, r * 0.8660254]) // 120 °
countersink([-r, 0]) // 180 °
countersink([-r * 0.5, -r * 0.8660254]) // 240 °
countersink([r * 0.5, -r * 0.8660254]) // 300 °