Fix for issue #26: BeamDyn initialization with non-zero initial azimuth

The initial translation velocity calculation didn't remove the location of the root node when taking the cross product with the rotational velocity. This fixes OpenFAST#26

modules-local/beamdyn/src/BeamDyn.f90

@@ -4021,10 +4021,6 @@ SUBROUTINE BD_CalcIC( u, p, x)
  REAL(BDKi) :: temp3(3)
  REAL(BDKi) :: temp_p0(3)
  REAL(BDKi) :: temp_rv(3)
- REAL(BDKi) :: temp_R(3,3)
- REAL(BDKi) :: GlbRot_TransVel(3) ! = MATMUL(p%GlbRot,u%RootMotion%TranslationVel(:,1))
- REAL(BDKi) :: GlbRot_RotVel_tilde(3,3) ! = SkewSymMat(MATMUL(p%GlbRot,u%RootMotion%RotationVel(:,1)))
- REAL(BDKi) :: temp33(3,3)
  CHARACTER(*), PARAMETER :: RoutineName = 'BD_CalcIC'
 
 
@@ -4070,10 +4066,12 @@ SUBROUTINE BD_CalcIC( u, p, x)
  temp_id = p%node_elem_idx(i,1)-1 ! Node just before the start of this element
  DO j=k,p%nodes_per_elem
 
- temp3 = p%uuN0(1:3,j,i) + x%q(1:3,temp_id+j)
- temp3 = u%RootMotion%TranslationVel(:,1) + cross_product(u%RootMotion%RotationVel(:,1),temp3)
+ ! Find distance vector from root
+ temp3 = (p%uuN0(1:3,j,i) + x%q(1:3,temp_id+j)) - (p%uuN0(1:3,1,1) + x%q(1:3,1))
+ ! Calculate translational velocity of tip relative to root, and add it to the root translational velocity
+ x%dqdt(1:3,temp_id+j) = u%RootMotion%TranslationVel(:,1) + cross_product(u%RootMotion%RotationVel(:,1),temp3)
 
- x%dqdt(1:3,temp_id+j) = temp3
+  ! Rotational velocity is the same as the root rotational velocity
  x%dqdt(4:6,temp_id+j) = u%RootMotion%RotationVel(1:3,1)
  ENDDO
  k = 2 ! start j loop at k=2 for remaining elements (i>1)