A lot of progress on the propagator

julia/propagator.jl

@@ -0,0 +1,36 @@
+"""
+This function propagates the spacecraft forward in time 1 Sim-Flanagan step (of variable length of time),
+applying a thrust in the center.
+"""
+function prop_one(ΔV_unit::Vector{Float64},
+                  state::Vector{Float64},
+                  duty_cycle::Float64,
+                  num_thrusters::Int,
+                  max_thrust::Float64,
+                  mass::Float64,
+                  mass_flow_rate::Float64,
+                  μ::Float64,
+                  time::Float64)
+
+  if norm(ΔV_unit) > 1.
+    throw(ErrorException("ΔV input is too high"))
+  end
+  halfway = laguerre_conway(state, μ, time/2)
+  halfway[4:6] += ΔV_unit * max_ΔV(duty_cycle, num_thrusters, max_thrust, time, 0., mass)
+  return laguerre_conway(halfway, μ, time/2), mass - mass_flow_rate*norm(ΔV_unit)*time
+
+end
+
+"""
+A convenience function for using spacecraft. Note that this function outputs a sc instead of a mass
+"""
+function prop_one(ΔV_unit::Vector{Float64},
+                  state::Vector{Float64},
+                  craft::sc,
+                  μ::Float64,
+                  time::Float64)
+  state, mass =  prop_one(ΔV_unit, state, craft.duty_cycle, craft.num_thrusters, craft.max_thrust,
+                          craft.mass, craft.mass_flow_rate, μ, time)
+  return state, sc(mass, craft.mass_flow_rate, craft.max_thrust, craft.num_thrusters, craft.duty_cycle)
+end
+