We present a course design model for applying project-based learning to an online undergraduate object oriented systems course. In our model, projects and reflection are central to the curriculum. Our model challenges students through modularized, repetitive project cycles beginning with analysis and design (i.e. using pseudo- code, flowcharts, diagrams) then coding, debugging, testing, and finally, reflection. We analyzed student reflection responses from two semesters to extract major themes and sub-themes, then mapped these to the MUSIC model (eMpowerment, Usefulness, Success, Interest, Caring) to understand our model's influence on student engagement and motivation. We found that a rhythmic project cycle encourages self-regulation in online students to formulate project plans, track their progress, and evaluate their solutions. Online students feel empowered when course projects promote choice, flexibility, creativity, experimentation, and extensions to other applications. Online student success is dependent on the clarity of instructions, course scaffolding, level of challenge, instructor feedback, and opportunities to reflect on personal failure, success, and challenge. Online students are interested in projects that are familiar, real-world, and fun, but expect to be situated in team-based environments. Students appreciate instructors who are caring and accommodating to personal needs. We recommend six salient strategies for improving online course and project design: design a visible, rhythmic structure; set transparent expectations and instructions; encourage design before implementation; connect to real-world applications and tools; experience happy challenges; infuse sustained reflection.