1 files changed, 79 insertions, 0 deletions
diff --git a/ao-tools/ao-fakeflight/ao-rocket.c b/ao-tools/ao-fakeflight/ao-rocket.c
new file mode 100644
index 00000000..18808c65
--- /dev/null
+++ b/ao-tools/ao-fakeflight/ao-rocket.c
@@ -0,0 +1,79 @@
+/*
+ * Copyright © 2014 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include "ao-fakeflight.h"
+
+/* Mass (kg) of the airframe */
+double
+rocket_mass(struct flight *f, struct rocket *r)
+{
+	double	time = f->time;
+	double	m = r->empty_mass;
+	int	n;
+
+	for (n = 0; n < MAX_MOTORS; n++) {
+		struct motor *motor = &r->motors[n];
+		if (motor->burn_time) {
+			double fuel_time_remain = fmin (motor->burn_time, fmax(motor->burn_time - (time - motor->delay), 0.0));
+			double fuel_fraction = fuel_time_remain / motor->burn_time;
+			m += fuel_fraction * motor->fuel_mass;
+		}
+	}
+	return m;
+}
+
+/* Force (N) due to thrust */
+double
+rocket_thrust(struct flight *f, struct rocket *r)
+{
+	double	time = f->time;
+	double	thrust = 0.0;
+	int	n;
+
+	for (n = 0; n < MAX_MOTORS; n++) {
+		struct motor *motor = &r->motors[n];
+		if (motor->burn_time) {
+			if (motor->delay <= time && time < motor->delay + motor->burn_time)
+				thrust += motor->average_thrust;
+		}
+	}
+	return thrust;
+}
+
+/* Drag (N) due to air resistance */
+double
+rocket_drag(struct flight *f, struct rocket *r)
+{
+	double	pressure = cc_altitude_to_pressure(f->altitude);
+	double	temperature = cc_altitude_to_temperature(f->altitude);
+	double	drag = force_drag(f->speed, density_air(pressure, temperature),
+			  r->models[f->state].cd,
+			  area_circle(r->models[f->state].diameter));
+
+	/* drag operates in opposition to motion through air */
+	if (f->speed >= 0)
+		drag = -drag;
+
+	return drag;
+}
+
+/* Force (N) due to gravity */
+double
+rocket_gravity(struct flight *f, struct rocket *r)
+{
+	double	gravity = force_gravity(rocket_mass (f, r), f->altitude);
+}