Formula: {Research_XCopter = UAV research @(United States)}


Development:
~ high performance airfoil designs and well validated design/analysis tools in the range of Reynolds numbers from 50,000 to 500,000

Challenges:
~ the performance penalty caused by low Reynolds number aerodynamics
~ the rotor blade chord size results in Reynolds numbers in the range of 50,000 to 250,000
~ in the range from 50,000 to 500,000 flow physics issues associated with laminar separation bubbles prevent accurate numerical simulation of new designs
~ Reynolds numbers from 50,000 to 500,000 cover small low-altitude portable UAVs and high altitude larger UAVs
~ the major challenge for VTOL UAVs is to achieve high-lift airfoil performance without generating high pitching moments
~ the constraint on pitching moment requires a truly innovative design in order to prevent
~ excess vibration, dynamic instabilities, and elastic deformations when the concept is applied to a rotor blade
Goals:
~ improved airfoil designs can impact mission effectiveness by improving performance
~ in terms of hover figure of merit, and cruise lift to drag ratio
Benefits to be achieved:
~ increased payload, range and endurance of the UAV platform
Research:
~ the understanding of how separation bubble flow physics change in the rotor environment
~ challenges of the rotor environment arise from a greater number of potential triggers for boundary layer transition
~ examples include cross flow instabilities from yawed flow, vortex wake induced freestream turbulence, and
~ high frequency elastic deformations
Design:
~ any new design must be able to either adapt or be immune to major changes in the transitional nature of the rotor blade boundary layer

catch ~XCopter!