diff --git a/classes/bays/Motor.m b/classes/bays/Motor.m
index 989c93865e47b291c48d638ab6b9896273344e47..39f6ed2d790b8a95a4acc8d1e12fab435921fe39 100644
--- a/classes/bays/Motor.m
+++ b/classes/bays/Motor.m
@@ -109,7 +109,10 @@ classdef Motor < Bay
 
             if obj.isHRE
                 obj.length          = chosenMotor.L;
-                obj.tankLength      = chosenMotor.Ltank;      
+                obj.tankLength      = chosenMotor.Ltank;
+                if isempty(obj.tankLength)
+                    obj.tankLength = chosenMotor.LtankPr + chosenMotor.LtankOx;
+                end
                 obj.fuelMass        = chosenMotor.mFu;  
                 obj.oxidizerMass    = chosenMotor.mOx;        
                 inertiaRaw          = [chosenMotor.Ixx;chosenMotor.Iyy;chosenMotor.Izz];