Many aircraft need to operate efficiently at more than one flight regime; for example, certain airframes are expected to perform in relatively high-speed cruise modes, as well as slower loitering scenarios. Unfortunately, an engine operates most efficiently when the exit velocity closely matches the speed of the...

Innovators at NASA’s Armstrong Flight Research Center are developing a collection of algorithms that can accurately determine the structural state of an aircraft. This work is in response to new airframe designs that save weight — and thereby improve fuel efficiency — by removing stiffness in...

Conventional transport aircraft wing design is driven mainly by cruise efficiency, i.e., adequate lift is generated at high speed for level flight with minimal drag. Conventional high-lift systems (leading edge slats and trailing edge flaps) were...

One of the more critical constraints to the continued growth of air traffic is the related concern regarding aircraft noise. This concern has resulted in increasingly stringent noise restrictions for airports, both nationally and internationally. One of the major stretch goals for NASA is to...

Aircraft noise is a significant problem with both economic and public health implications, especially for communities near airports. As a result, increasingly stringent constraints are being placed on aircraft carriers worldwide to reduce this noise. The current disclosure focuses on airframe noise generated at or...

An optical link from Earth to an aircraft demonstrates the ability to establish a link from a ground platform to a transceiver moving overhead. An airplane has a challenging disturbance environment including airframe vibrations and occasional abrupt changes in attitude during flight. These...

New flow effector technology for separation control and enhanced mixing is based upon shape memory alloy hybrid composite (SMAHC) technology. The technology allows for variable shape control of aircraft structures through actively deformable surfaces. The flow effectors are made by embedding...

Proprotor Aeroelastic Stability Analysis, now at version 4.5 (PASTA 4.5), is a FORTRAN computer program for analyzing the aeroelastic stability of a tilt-rotor aircraft in the airplane mode of flight. The program employs a 10-degree-of-freedom (DOF), discrete- coordinate, linear mathematical...

Buffet loads on aft aerodynamic surfaces pose a recurring problem on most twin-tailed fighter airplanes: During maneuvers at high angles of attack, vortices emanating from various surfaces on the forward parts of such an airplane engine inlets, wings, or other fuselage appendages) often burst,...

FWH2D is a Fortran 90 computer program that solves a two-dimensional (2D) version of the equation, derived by J. E. Ffowcs Williams and D. L. Hawkings, for sound generated by turbulent flow. FWH2D was developed especially for estimating noise generated by airflows around such approximately 2D...