From 62cd6c3204518c5e4920035b3ababdf8cb224d64 Mon Sep 17 00:00:00 2001
From: Brendan McGeeney <bpmcgeeney@gmail.com>
Date: Thu, 16 Sep 2021 23:35:43 +0000
Subject: [PATCH] Replace burnStartTimeCalc.m

---
 burnStartTimeCalc.m | 38 ++++++++++++++++++--------------------
 1 file changed, 18 insertions(+), 20 deletions(-)

diff --git a/burnStartTimeCalc.m b/burnStartTimeCalc.m
index f646a79..8eee565 100644
--- a/burnStartTimeCalc.m
+++ b/burnStartTimeCalc.m
@@ -1,27 +1,25 @@
-function [h0, vb, burnStartTime] = burnStartTimeCalc(Tcurve, tb, M0, mdot, Mb)
-Mavg = (M0 + Mb)/2;
+function [h0, vb, burnStartTime] = burnStartTimeCalc(Tcurve, tb, M0, mdot, Mb, v0)
 g = -9.81;
+v_prev = v0;
+h_prev = 0;
 
-A_tot = 0;
-
-% Riemann Sum
-for i = 2:length(Tcurve)
-    if i > 1
-        A = (Tcurve(i, 1) - Tcurve(i - 1, 1)) * Tcurve(i, 2);
+for i = 1:length(Tcurve)
+    if i < length(Tcurve)
+        dt = Tcurve(i + 1, 1) - Tcurve(i, 1);
+        a = (Tcurve(i, 2) / (M0 - mdot * Tcurve(i + 1, 1))) + g;
     else
-        A = Tcurve(i, 1) * Tcurve(i, 2);
+        dt = 0;
+        a = (Tcurve(i, 2) / Mb) + g;
     end
-    A_tot = A_tot + A;
+    
+    v = a * dt + v_prev;
+    v_prev = v;
+    h = v*dt + h_prev;
+    h_prev = h;
 end
 
-Tavg = A_tot / tb;
-ueq = Tavg / mdot;
-delta_ub = ueq * log(M0/Mb) + g*tb;
-a_avg = (Tavg/Mavg) + g;
-
-hf = ((delta_ub^2) / (2*-g));
-hb = ((delta_ub^2) / (2*a_avg))
-
-h0 = hf + hb + 1;
-vb = delta_ub;
+hb = h;
+hf = v^2 / (2*-g);
+h0 = hb + hf;
+vb = v;
 burnStartTime = vb / -g;
\ No newline at end of file