Recovered from patate

ksp_toolbox/plane_change.py

@@ -0,0 +1,53 @@
+import math
+from math import pi, sqrt, sin
+
+
+class Const:
+    G = 6.67408e-11
+
+    class Mun:
+        M = 9.7599066e20
+        R = 200e3
+
+
+def withbody(fun):
+    def wrapped(*args, body=None, **kwargs):
+        if body is None:
+            body = Const.Mun
+        return fun(*args, body=body, **kwargs)
+
+    return wrapped
+
+
+@withbody
+def v_at(r, body, a=None):
+    if a is None:
+        a = r
+    return sqrt(Const.G * body.M * ((2 / r) - (1 / a)))
+
+
+@withbody
+def dv_change_alt(r1, r2, rconst, body):
+    """Δv to change the opposite side from r1 to r2, being at rconst"""
+    v_cur = v_at(rconst, body=body, a=(rconst + r1) / 2)
+    v_target = v_at(rconst, body=body, a=(rconst + r2) / 2)
+    return v_target - v_cur
+
+
+@withbody
+def dv_plane_change(theta, r, a, body):
+    return 2 * v_at(r, body=body, a=a) * sin(theta / 2)
+
+
+@withbody
+def dv_total(r_init, theta, r_high, body):
+    return (
+        abs(dv_change_alt(r_init, r_high, r_init, body=body))
+        + abs(dv_plane_change(theta, r_high, (r_high + r_init) / 2, body=body))
+        + abs(dv_change_alt(r_high, r_init, r_high, body=body))
+    )
+
+
+@withbody
+def dv_total_alt(alt_init, theta, alt_high, body):
+    return dv_total(alt_init + body.R, theta, alt_high + body.R, body=body)