Engine Room · Demo
No pistons, no valves, two moving parts — a triangle doing all four strokes at once.
A piston four-cylinder needs some forty moving parts to do what this does with two. The catch lives at the corners: the apex seals scrub the housing at every angle, and the long, thin chambers burn incompletely — the thirst and the smoke that eventually killed it.
In plain terms
A Wankel replaces pistons, valves, con-rods and camshafts with one triangular rotor orbiting inside a peanut-shaped housing. The triangle's corners always touch the wall, so its three sides wall off three separate chambers — and as the rotor rolls round, each chamber in turn swells past the intake port, gets pinched to a sliver, burns at the plugs, and breathes out through the exhaust. All four strokes happen every moment, just in different places. The output shaft spins three times per rotor turn, collecting one bang per revolution.
The housing is a two-lobe epitrochoid with eccentricity and generating radius :
where is the rotor angle. The rotor centre rides the shaft's eccentric of radius at , and each apex sits at on the same curve — which is why the corners never leave the wall. Chamber volume swings sinusoidally between its extremes once per rotor turn per face; the compression ratio is set by and the recess milled into each flank. Port timing, seal leakage and combustion are not modelled — this is the geometry, which is the part nobody believes until they watch it.