Microgravity platforms enable the study of physical phenomena at near-zero gravity conditions. Space stations, space shuttles and spacecraft orbiting Earth, sounding rockets, high-altitude balloons and drop towers from which experimental payloads can be dropped, and manned airplanes performing specialized maneuvers are the currently used microgravity platforms. This thesis presents the development of a new class of low-cost, portable, and easily accessible microgravity platforms—unmanned multirotor microgravity platforms.

Towards turning a multirotor into a microgravity platform, a vertical maneuver with time-varying acceleration is proposed. A multirotor performing such a maneuver and its onboard payload will experience microgravity. The multirotor's drag and propeller thrust coefficient will vary with its vertical speed during this microgravity enabling maneuver. This thesis develops control and estimation strategies and methods that enable a multirotor to maintain the desired accelerations despite these variations.

These methods were implemented on two multirotors—a modified hexrotor and a conventional quadrotor. The microgravity enabling flight tests performed using these multirotors yielded near-zero gravity flight time of more than 1.5 seconds. Further, experiments to observe the effect of microgravity on liquid level in a capillary and liquid meniscus shape in a glass cuvette were performed onboard. These experiments and the microgravity enabling flight tests demonstrate the efficacy of multirotors as portable microgravity platforms. This thesis also derives relations to analyze the capability of existing multirotors as microgravity platforms, provides a methodology to design new multirotor microgravity platforms, and suggests methods to improve the performance of multirotors as microgravity platforms.