need some help on modifying my simulink model

I have created a simulink model for an inverted airfoil mounted on a moving cart( similar to the classical cart-inverted pendulum system).Attached here are my simulink model and my derivation of equations of motion.

Currently,there are 2 issues with my model. First, the simulation can't run if the stop time is greater than 0.44 seconds. I get an error saying the model is ill-defined. Second, when I truncate the run time to less than 0.44 seconds, I get a algebraic loop warning. Could someone please give me some suggestions on how to modify my Simulink model?Thanks a bunch.