refact(config): more generic coax template

src/configs/templatecoax.m

 % TEMPLATECOAX Template configuration file for Coaxial rotors simulations with Rotare.
-%  This file extends the regular template configuration by adding a second rotor geometry.
+%  This file extends the regular template configuration by adding N-1 coaxial rotors.
 % -----
 %
 % See also: template, rotare, validconfig.
@@ -16,37 +16,44 @@
 % Issues: https://gitlab.uliege.be/rotare/rotare/-/issues
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
+N_ROTORS = 4; % Total number of rotors in coaxial configuration, [-]
+
 % ==================================================================================================
 % ================================== Baseline configuration ========================================
 % ==================================================================================================
 % Just load exisiting template
 template;
 
-Sim.Out.show3D    = false;  % Show the 3D view of the whole rotor
-% Currently only indvel is supported fro coaxial
-% Mod.solvers = 'indvel';  % BEMT Solver ('leishman', 'indfact', 'indvel', 'stahlhut', 'all')
-
-% ==================================================================================================
-% ================================= Blade and rotor geometry =======================================
-% ==================================================================================================
-% Adds a second element to the blade structure to represent the second rotor
-
-Blade(2) = Blade(1); % Make second rotor identical to first one
-Blade(2).spinDir = -Blade(1).spinDir; % Spin in opposite direction from first rotor
+Sim.Out.show3D = false; % Disable 3D as it is not supported for coaxial (yet)
 
-% Shift second rotor w.r.t the application type
-if strcmp(Sim.Misc.appli, 'heli')
-    rotorShift = [0, 0, -1] * Blade(1).radius(end);
-else
-    rotorShift = [-1, 0, 0] * Blade(1).radius(end);
-end
-Blade(2).hubPos = Blade(1).hubPos + rotorShift;
+% FIXME: Currently only indvel is supported for coaxial
+Mod.solvers = 'indvel';  % BEMT Solver ('leishman', 'indfact', 'indvel', 'stahlhut', 'all')
 
 % ==================================================================================================
-% ===================================== Operating points ===========================================
+% ====================================== COAXIAL SYSTEM  ===========================================
 % ==================================================================================================
-
-% Operating points must be set for the two rotors
-% We simply extend the collective and rpm fields by adding values for the new rotor
-Op.collective = [Op.collective; 1, 4, 7];
-Op.rpm = [Op.rpm; 900, 1200];
+% Adds a as many rotors as required, based on the initial blade geometry
+
+% First rotor settings for collective and RPM
+init_coll = Op.collective;
+init_rpm = Op.rpm;
+Blade(N_ROTORS - 1) = Blade(1); % Pre-alloc
+
+for i = 2:N_ROTORS
+
+    % ================================ Blade and rotor geometry ====================================
+    Blade(i) = Blade(1); % Make second rotor identical to first one
+    Blade(i).spinDir = -1 * Blade(i - 1).spinDir; % Invert spin direction for each rotor
+
+    % Shift second rotor w.r.t the application type
+    if strcmp(Sim.Misc.appli, 'heli')
+        rotorShift = [0, 0, -1] * Blade(i - 1).radius(end);
+    else
+        rotorShift = [-1, 0, 0] * Blade(i - 1).radius(end);
+    end
+    Blade(i).hubPos = Blade(i - 1).hubPos + rotorShift;
+
+    % =================================== Operating points =========================================
+    Op.collective = [Op.collective; init_coll];
+    Op.rpm = [Op.rpm; init_rpm];
+end