Radius of circular hole

Hello,

I have this simple example of a quad with a circular hole:

+PROG AQUA urs:1

NORM DC US NDC AASHTO-2014 COUN US UNIT 0 LANG 1 G 10

STEE NO 8 TYPE S  FY 345 TMAX 55 GAM 78.5*1.15 TITL 'A709 GR. 50'

STEE NO 9 TYPE S  FY 235 TMAX 55 GAM 78.5*1.15  TITL 'A106 GR. B'

END

+PROG SOFIMSHC urs:2

SYST 3D GDIR POSZ GDIV 100000

CTRL MESH   2+64
CTRL HMIN   0.05

SPT NO 100 SX 1.0

LET#PHI_INT 200
LET#ALPHA 60.0

SLN NO 101
SLNB XM 0.0 ZM 0.0 NX +COS(#ALPHA) NZ -SIN(#ALPHA) R #PHI_INT/2/SIN(#ALPHA)[MM]

SPT NO    X               Y        Z
    1    -0.5*SIN(#ALPHA)  0.5     -0.5*COS(#ALPHA)
    2    +0.5*SIN(#ALPHA)  0.5     +0.5*COS(#ALPHA)
    3    +0.5*SIN(#ALPHA)  -0.5     +0.5*COS(#ALPHA)
    4    -0.5*SIN(#ALPHA)  -0.5     -0.5*COS(#ALPHA)

SAR NO 1 MNO 8 T 10[MM] GRP 11 QREF CENT
SARB  NA   NE
      1    2
      2    3
      3    4
      4    1

SARB TYPE IN NL 101

SLN NO NPA  NPE  FIX=PP
    1  1    2
    2   2   3
    3   3   4
    4  4    1

END                                                 

I ended up including a factor of “/SIN(#ALPHA)” in the radius of the SLNB to get the same hole for any “#ALPHA” (angle of the quad). This behaviour seems strange to me. Shouldn’t the hole be of the same radius for any “#ALPHA” without that factor? I’m a bit astonished.

Thanks and regards,

Gonzalo