This engine gets its power from the expansion and contraction of a geometry (the red box inside the cylinder). It's similar to a "spawn engine", but rather than spawn a new geometry inside the cylinder during each power stroke, I used one single geometry that expands during each power stroke, and then collapses back down during the return stroke of the piston. The expansion is controlled by the angle of the flywheel. As the flywheel is rotating, its angle is converted through a simple math routine into the length of the red box. As the box grows longer, it pushes on the piston, causing the flywheel angle to increase, which further increases the length of the red box. At bottom-dead-center, the flywheel angle quickly changes to a negative value, which causes the length of the box to snap back down to very narrow. At top-dead-center, the angle becomes positive again, and the process repeats.
I searched Algobox quite thoroughly and did not find another engine that operates on this principle. So, I believe that this is an Algodoo first. If anyone finds a similar scene that I missed, please let me know so that I can give credit to someone else for this idea.
I admit that I'm not very good at creating mechanical devices with Algodoo, so please go easy on me with your criticisms!
