Energy harvesting for parafoil and payload aircraft systems

Abstract

Guided airdrop systems offer an efficient and reliable means of delivering payloads to remote or hard-to-access locations. Utilizing a set of sensors and actuators, the Airborne Guidance Unit (AGU) intelligently controls the aircraft to a desired impact point (IP). These onboard electronics are powered using high-power-density batteries such as Lithium Polymer or Nickel Metal Hydride batteries. A logistics issue for guided airdrop systems is maintaining these batteries inside the AGU so that when the system is deployed, the batteries are adequately charged and are able to provide the requisite power to the system. It is typical for a guided airdrop system to be packed and readied for use well before deployment leading to non-negligible battery self-discharge. This necessitates a process to monitor battery life and recharge the systems after a certain time interval. This paper explores using a small-scale wind energy harvesting system to provide the necessary power for the onboard electronics and actuation for a guided airdrop system. Sizing studies are reported to estimate the required scale of both the turbine rotor and generator. Using this information, a full-scale AGU with an integrated twin horizontal axis wind turbine system was designed, fabricated, and tested in a wind tunnel to determine the system’s viability. Results indicate that a 0.33 m diameter turbine system can generate over 3.7 W of continuous power at a wind speed of 8 m/s. This is sufficient to power low-power consumption guided airdrop systems, such as a bleed air actuated system.