Reactionless and inertial drives under the microscope: Mach-effect thrusters, gyroscopic devices, and momentum-exchange concepts. Learn the theory, the rigs, and the data quality standards. Our goal is reproducible measurements that separate genuine thrust from vibration or test-stand bias. For over a decade, Bryan St. Clair has been building, breaking, refining, and rethinking a family of inertial propulsion devices he believes can turn timed internal motion into useful thrust. At APEC, he presented his technical journey and findings. In the wake of James F. Woodward’s death, one of his closest collaborators is carrying forward one of the most controversial propulsion programs in modern physics—an effort to determine whether a vibrating stack of piezoelectric crystals can produce propellantless thrust. Some inventions begin as equations. Sandy Kidd’s began as a shove—an aircraft gyroscope pushing back so hard it felt, for an instant, like the machine had a will of its own. The physics explores angular momentum and potential asymmetric forces in mechanical gyroscopic systems. In the Russian alternative-propulsion world, “reactionless drive” doesn’t always mean hidden rockets or exotic fields. Sometimes it means something much stranger—and much more mechanical: a sealed device utilizing liquid vortices and gyroscopic mechanics. In 2009, Russian headlines carried an unexpected story: the educational satellite Yubileiny—launched the year before to commemorate the 50th anniversary of Sputnik 1—was reportedly testing an experimental “reactionless” drive in orbit. For more than a century, physicists have stretched Newton’s laws with relativity and quantum mechanics. A fourth extension, rooted in the geometry of “torsion” and championed by Russian theorist Gennady Shipov, explores theoretical and mechanical 4-D gyroscopic motion. At Cal State Fullerton, a revolutionary propulsion program aims at the unthinkable: thrust without propellant, a steady shove drawn from the physics of inertia. For over thirty years, James F. Woodward led that effort through the Mach Effect Gravity Assist (MEGA) drive. Dr. James Woodward demonstrates experimental testing with the Mach Effect Gravity Assist (MEGA) drive using a 150g device and an 885g support structure. Woodward's team used a Logitech Trio to record device motion and precise instrumentation to measure transient thrust. Dr. James F. Woodward discusses Mach Effect Propulsion & the Mach Effect Gravity Assist (MEGA) drive, an experimental propulsion system designed to leverage transient mass fluctuations as the basis for a new form of space propulsion. Dr. James Woodward discusses Mach Effect Propulsion, which postulates that energy-storing ions experience transient mass fluctuations when accelerated. Unlike conventional technologies, drives based on the Mach Effect operate without chemical propellants.