The Integrated Modular Avionics (IMA) architecture has been a crucial concern for the aerospace industry in developing more complex systems, while seeking to reduce space, weight and power (SWaP), as well as development, certification and production time. From a software perspective, that objective pushes developers to migrate toward safety critical space and time partitioning environment. However, mainstream commercial real-time operating systems (RTOS) offering such partitioning can be restrictive in early development due to very high licensing costs. That situation is even more striking when considering that low-cost alternatives could instead be used for system modeling and early simulation before acquisition of a target platform.This paper reviews existing low-cost and open-source development environments to propose a novel design flow. The proposed methodology starts with model-based analysis in the AADL modeling language. Then, configuration files and software integration code are generated and executed using the Simulated IMA (SIMA) software from GMV. A case study experiment was created using a Multi-purpose Control and Display Unit (MCDU) communicating with an external Flight Management System (FMS) simulation provided by our industrial partner CMC Electronics. Results show reduction of time for system and partition configurations from hours to seconds, notably by reducing human error. It also proves useful in identifying design flaws in early development as well as facilitating software architectural exploration for integrated modular avionics.