Description: Multi-rotors (e.g. quad-copters) typically have direct electric drive, where the electric motor shaft is directly coupled to the propeller shaft. The benefit of this configuration is simple and high fidelity control. But electric drive for vertical lift typically relies on lithium polymer batteries for energy storage, and battery specific energy is extremely low compared to internal combustion fuels; Gasoline has about a 15X advantage over rechargeable batteries and diesel has about an 18X advantage. Current unmanned multi-rotor aircraft do not have the endurance or payload capability to act in place of manned observatory platforms (rechargeable batteries deliver at most two hours of endurance for multi-rotor aircraft with no payload). However, frequency response requirements tend to prohibit direct drive from an internal combustion engine. Aurora proposes to develop a reformulated Miller Cycle engine in Series Hybrid Architecture for use in small unmanned vertical lift aircraft to combine the benefits of both direct electric drive and internal combustion engine technology. The reformulated Miller Cycle will also confront the fuel mixing issues associated with sUAS sized small engines.

Benefits: In this proposal, a reformulated Miller cycle is presented as a method for both increasing the endurance of small unmanned vertical lift aircraft and overcoming fuel mixing issues associated sUAS sized engines. With greater endurance and payload it is expected that a multi-rotor observatory platform would be suitable for many earth science missions: - Volcanic Plume research - Wildfire Tracking - Highly localized emission in urban environments

The Passive Miller Cycle in a Series Hybrid Architecture could be integrated into a number of Tier 1 (<50 lb) UAV's and used to substantially increase the endurance and payload. Current unmanned multi-rotor aircraft do not have the endurance or payload capability to act in place of manned observatory platforms, but with a Passive Miller Cycle Series Hybrid, endurance and payload could meet the requirements that manned systems do today. The unmanned multi-rotor has many advantages over manned helicopter systems: - Takeoff and landing - Buy-in cost - Operating cost Two specific markets where unmanned multi rotors can augment existing manned helicopter operations are in Electronic News Gathering and law enforcement.