Pneumatic Solutions for Extreme STOL Aircraft Critical Technologies

The current interest in Extreme STOL technology is intended to develop technology to provide future fixed-wing transport aircraft with very high lift capability for very short (<2000′) balanced-field-length operations plus efficient transonic cruise (M ∼ 0.8). However, this carries with it the need for a number of additional capabilities that could be simultaneously unobtainable if only conventional aerodynamic and control technologies are employed. These requirements include: high powered-lift values (C_L∼10) with the associated low-speed moment-trim requirement; low-speed control including one-engine out; interchangeable lower drag (for cruise and climb) and increased drag (for equilibrium approach); cruise efficiency; quiet operation; leading-edge stall prevention; reduced mechanical complexity and weight; and system simplicity, reliability, and maintainability. The following paper will present and support the premise that pneumatic (blown) technology can be employed to perform all of the above functions with properly integrated blown components performing multiple functions, in many cases without the use of any external moving surfaces or actuators. This paper will include discussions of these technologies, accompanied by recent small-scale and/or flight-test data to confirm these capabilities. Also included will be recent research into means to further reduce the already-low blowing mass flows required to yield these results.