DEVELOPMENT AND TESTING OF A SURROGATE UNMANNED AIRCRAFT FOR CREW TRAINING AND EVALUATION OF FLIGHT TEST PROCEDURES FOR A HIGH-ALTITUDE PLATFORM

Abstract

The German Aerospace Center (DLR) is currently developing a solar-powered high-altitude platform (HAP) in the context of the DLR-internal project HAP-alpha. The project addresses the complete development process of the aircraft, from conceptual studies and detailed design up to its construction, flight test campaigns, and the final operation procedures. Generally, HAPs are in terms of flight characteristics and flight performance unconventional due to their highly flexible structure, extremely low weight, and high glide ratio. Furthermore, the flight test of such a highly fragile aircraft poses significant challenges in terms of flight test procedures, system identification maneuvers as well as the Beyond Visual Line of Sight (BVLOS) operation. Therefore, a surrogate aircraft was developed to train the crew and evaluate suitable flight test procedures. This surrogate aircraft is a highly modified commercial off-the-shelf (COTS) radio controlled (RC) sail plane. The aircraft features a flight controller to approximate the maneuverability and flight performance of the HAP and a FirstPerson View (FPV) system comparable to the HAP. The surrogate aircraft is modified to have a comparable engine arrangement to that of the HAP, and the controller is tuned such that similar angular rates, and climb performances are obtained. In this paper the design considerations, development tests and a brief overview of the crew training is given. In addition, the results of flight tests are presented. These include a general feasibility test of performing system identification maneuvers with the aircraft and a test dealing with turning flight in HAP mode.