Droop
fig. a: droop
The droop angle of a pigtail is defined as the angle between the tangent to the pigtail baseline at the pigtail origin and the normal to the head surface. Ideally, this angle is zero degrees. Droop is strongly related to pigtail tightness.
fig. b: (nearly) zero droop
fig. c: 20° droop
fig. d: 60° droop