File:Magsail MHD and kinematic model effective sail area.jpg

English: The figure plots the normalized effective sail area normalized by the coil area ${\displaystyle \pi R_{c}^{2}}$ for the Magsail kinematic model (MKM) from Gros ${\displaystyle A_{G}(v)}$ and for Zubrin ${\displaystyle A_{Z}(v)}$ for loop current ${\displaystyle I=I_{G}}$ a curve fit parameter plotted versus the spacecraft velocity relative to the speed of light ${\displaystyle v/c}$ assuming an Interstellar medium (ISM) plasma density of 1.7x10^-22. Also plotted is the MHD applicability test of ion gyroradius divided by magnetopause radius ${\displaystyle r_{g}/R_{mp}}$ < 1 on the secondary axis. Note that MHD applicability occurs at ${\displaystyle v/c}$ < 1%. For comparison, the 2004 Fujita ${\displaystyle C_{d}}$ model as a function of ${\displaystyle r_{g}/R_{mp}}$ from the MHD applicability test section of the magnetic sail article is also plotted. Note that the Gros model predicts a more rapid decrease in effective area than this model. The normalized values of ${\displaystyle A_{G}(v)}$ and ${\displaystyle A_{Z}(v)}$ track closely until ${\displaystyle v/c\approx }$ 10% after which point the Zubrin magsail model becomes increasingly optimistic and the MKM model is applicable instead. Since the models track closely up to ${\displaystyle v/c\approx }$ 10%, with the kinematic model underestimating effective sail area only for small values of ${\displaystyle v/c}$ (hence underestimating force),the MKM model is a good approximation for predicting generation of force both the MHD and kinematic region.