Recommendation. The U.S. Air Force long-term UAV research program should focus on crosscutting subsystem technologies.
The need for affordability and short design cycles that underlies much of the interest in UAVs will require changes in design practices, resulting in increased reliance on computational modeling, simulation, verification, testing, and training. Although these technologies could greatly reduce cost and cycle time, they also raise serious concerns about the fidelity of models and about their inherent uncertainties. Unfortunately, many sources of real error, from the intrinsic variability of the real world being modeled to the multitude of assumptions and approximations introduced in the modeling and simulation steps, cannot presently be accounted for formally and explicitly. Research opportunities for the development and validation of computational modeling and simulation tools are listed below:
development, validation, and application of computational tools for major subsystem design, including unsteady, nonlinear, three-dimensional aerodynamics models; structural analysis and aeroelasticity models; aerodynamic modeling concepts for designing vehicle control systems; propulsion system models; and simulation models for assessing new control laws
validation of manufacturing process models for UAV components
clarification of the role of uncertainty in computational analysis
integration of models and simulations to provide “virtual mockups” for testing and evaluation of the total system
In the past, development costs have been a major factor in the development of UAV propulsion technology. The development of an all-new gas turbine for a tactical military aircraft can cost more than $1 billion, an inconceivable expense for a low-cost UAV development program. To meet program budget constraints, the practice has been to adapt existing devices, usually at the expense of both performance and reliability. The cost of new technology, especially of new concepts, will be as high for UAV development programs as it has been for conventional aircraft unless new ways of developing propulsion systems can be perfected. To address this concern, the committee recommends that research be focused on technologies to enable development of small, low-cost turbine engines. The following topics should be considered: