The Delta v (normed with the initial velocity) requirement for four different transfers between circular orbits around a central body is depicted in dependence of the ratio of the two radii: Hohmann transfer (blue), bi-parabolic transfer (green), bi-elliptic transfer $\alpha=\frac{r_b}{r_1}=20+\frac{r_2}{r_1}$ and bi-elliptic transfer $\alpha=\frac{r_b}{r_1}=100+\frac{r_2}{r_1}$. The interesting part between 11,94 and 15,58 is zoomed in.
<a href="//commons.wikimedia.org/w/index.php?title=User:%C3%85nt%C3%B8in%C3%A6&amp;action=edit&amp;redlink=1" class="new" title="User:Åntøinæ (page does not exist)">Åntøinæ</a>
<span class="int-own-work" lang="en">Own work</span>