SEARCH · Search NASA
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Longitudinal aerodynamic characteristics of delta wings with curved & straight leading edges from mach 3 to 6
Longitudinal aerodynamic characteristics of nose cylinder-flare reentry bodies measured in hypersonic wind tunnel
Longitudinal aerodynamic characteristics of wing body tail combination at high subsonic speeds
Wind tunnel tests to determine longitudinal aerodynamic characteristics of large scale semispan V/STOL tilt-wing configuration with single propeller
Surface instability and disintegration of liquid in longitudinally excited container
Lateral and longitudinal aerodynamic characteristics of hypersonic missile configurations with canard controls in supersonic pressure tunnel
Longitudinal aerodynamic characteristics of large scale semispan V/STOL tilt-wing configuration having single propeller
Dynamics tests of engine-structure coupled longitudinal oscillations of Atlas Centaur Surveyor
Radial electron density profile and critical longitudinal magnetic field for helical current convective instability in hollow plasma column via Langmuir probe measurements
Longitudinal aerodynamic stability of three hypersonic aircraft at Mach numbers from 0.065 to 10.70
Two problems crucial to the stability of longitudinal acoustic waves in solid rocket motors were examined experimentally. The first is the dissipation of energy associated with an average flow inward at the lateral boundary. Measurements reported here, though subject to considerable experimental error, show that the actual losses are much larger than predicted by the approximate one dimensional analysis. The second problem is the attenuation of waves accompanying reflection by the nonuniform flow in a choked exhaust nozzle. Emphasis on technique, to provide data relatively easily and inexpensively. It appears that good results can be obtained in a routine manner using small supersonic wind tunnel operated as an open cycle. At least for Mach numbers up to 0.04 at the nozzle entrance, difficulties with signal/noise are satisfactorily overcome with a tracking filter.
A method of the unsteady suction analogy is developed using the unsteady quasi-vortex-lattice method which accurately predicts unsteady leading-edge and side-edge suction forces, and applies to any reduced frequencies. The importance of vortex lag is demonstrated, and damping derivatives, including roll and pitch damping derivatives with reduced frequencies and angles of attack are accurately predicted. Agreement of predicted pitch stiffness derivatives, however, is found to depend on the Reynolds number, possible aeroelastic effect, and the degree of edge-separated vortex flow on the model. Applications to the prediction of longitudinal dynamic stability derivatives for slender wings at high angles of attack are also presented.
A high power channeled substrate planar AlGaAs diode laser with an emission wavelength of 8600 to 8800 A was developed. The optoelectronic behavior (power current, single spatial and spectral behavior, far field characteristics, modulation, and astigmatism properties) and results of computer modeling studies on the performance of the laser are discussed. Lifetest data on these devices at high output power levels is also included. In addition, a new type of channeled substrate planar laser utilizing a Bragg grating to stabilize the longitudinal mode was demonstrated. The fabrication procedures and optoelectronic properties of this new diode laser are described.
This paper describes the use of nonlinear dynamic inversion for the design of a flight control system for a supermaneuverable aircraft. First, the dynamics to be controlled were separated into fast and slow variables. The fast variables were the angular rates and the slow variables were the attitude angles. Then a nonlinear inversion controller was designed for the fast variables. This stabilized the longitudinal short-period and improved the lateral-directional responses over a wide range of angle of attack by making use of a combination for aerodynamic surfaces and thrust vectoring control. Outer loops were then closed to allow the pilot to control the slow dynamics, the angle of attack, side-slip angle and the velocity bank angle. Nonlinear inversion was also used to design of the outer loop control laws. The dynamic inversion control laws were compared with more conventional, gain-scheduled control laws and were shown to yield much better performance.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.