Estimation of Load on Control Lines of Ram Air Parachute Designed for Precise Delivery Using 9-Dof Model

Abstract

Controlled Aerial Delivery System (CADS) consists of Ram Air Parachute (RAP) Airborne Guidance Unit (AGU) and useful payload. AGU pulls the control lines attached to the control surfaces of RAP and provides required maneuverability to the system. Estimation of load on control lines is essential for design and development of Airborne Guidance Unit (AGU). This paper presents the mathematical methods of the estimation of load on control lines the results of which are validated by experiments. The mathematical estimate of the load on control lines was carried out by developing a model similar to the aircraft control surface hinge moment estimation. The mathematical model was incorporated in 9DOF model to arrive at real time load estimation on control lines during inflation and subsequent steady flight condition. Experimental results are obtained during flight trials by using load cells on control lines and current sensor on power line of actuators. The mathematical results are in good agreement with the experimental results. The load on control lines are within 6 to 8% of the suspended load.