Iron Man's suit achieves flight through a fictional propulsion system that is not explicitly detailed in the movie. The suit's primary technology is its highly energy-dense power source located in the chest, which allows for advanced capabilities. Discussions suggest that if one had a lightweight, nearly infinite power source, innovative methods like heating air to create plasma could theoretically enable flight. However, the practicality of such propulsion methods is questioned due to material and energy constraints in reality. Overall, the suit's flight remains a blend of imaginative technology and cinematic creativity.