function [coeffdrag] = DragInterpolations_Spark(velocity, altitude)

spark_drag_data = dlmread("Spark/Spark_DragData.txt", "\t",1,0); 

[temp, sound_speed, P, rho] = atmosisa(altitude);
mach_speed = velocity/sound_speed;

mach = spark_drag_data(:,1);
drag = spark_drag_data(:,2);

coeffdrag = interp1(mach, drag, mach_speed);
end