To address the U.S. Air Forces (USAFs) need for a digital twin (DT) of the B-52H Stratofortress legacy aircraft to simulate aircraft equipment integration and testing, extreme weather condition effects, equipment failures, and system malfunctions, Intellisense Systems, Inc. (Intellisense) proposes to develop a new fully functional Stratofortress Intelligent Digital Twin (SINDIT). SINDIT is based on the original synthesis of artificial intelligence/machine learning (AI/ML), model-based systems engineering, and physically based modeling approaches in a physics-informed ML (PIML) neural network (NN). Specifically, the SINDIT PIML development and training will incorporate (a) physical principles (physical-based engineering descriptions, enforced physical constraints, physical-based regularization, stochasticity, multiscale properties, etc.); (b) USAF requirements and specifications; and (c) B 52 engineering domain knowledge, resulting in a physically and engineering-consistent DT validated through comparison to the actual aircraft. Intellisense will first use AI/ML techniques to create precise 3D CAD and SysML models of the B-52, including all its components, structures, subsystems, and equipment. Then, Intellisense will develop digital models of the interactions between all the components, structures, subsystems, and equipment, including engines and flight control systems. Finally, the B-52s numerical models of the components and structures and their interactions will be integrated into the full SINDIT, which will provide a safer, more efficient, and cost-effective way to test and integrate new equipment with the legacy B-52H Stratofortress. In Phase I, Intellisense will perform a feasibility study and develop an approach for creating a DT of the B-52 legacy system. We will train and test NNs to develop 3D CAD and SysML models and provide SINDITs initial architecture and design. In Phase II Intellisense will develop a 3D CAD model of the B-52 legacy aircraft and its subsystems for equipment integration and testing. The initial SINDIT Phase II prototype will be developed to simulate the integration of new equipment with the legacy aircraft. At the end of Phase II, we will demonstrate a well-defined deliverable Phase II SINDIT prototype for equipment integration and testing, followed by the development of a commercialization plan for SINDIT.