Engineering topics
Publications and source records attributed to Painter, W. D..
The rotor systems research aircraft (RSRA) has undergone ground and flight tests, primarily as a compound aircraft. The purpose was to train pilots and to check out and develop the design flight envelope. The preparation and flight test of the RSRA in the airplane, or fixed-wind, configuration are reviewed and the test results are discussed.
The Rotor Systems Research Aircraft (RSRA) has been undergoing ground and flight tests by Ames Research Center since late 1979, primarily as a compound aircraft. The purpose was to train pilots and to check out and develop the design flight envelope established by the Sikorsky Aircraft Company. This paper reviews the preparation and flight test of the RSRA in the airplane, or fixed-wing, configuration and discusses the results of that test.
The B-57B Severe Storms Flight Program gathers data to characterize atmosphere anomalies such as wind shear, turbulence, and microbursts at altitudes up to 1000 feet (300 meters). These data are used to enhance the knowledge of atmospheric processes, to improve aviation safety, to develop systems technology and piloting technique for avoiding hazards and to increase the understanding of the causes of related aircraft accidents. The NASA Dryden Flight Research Facility B-57B aircraft has participated in several severe storms data collection programs such as the Joint Airport Weather Studies (JAWS) located in Denver, Colorado area, Operation Rough Rider located in the Norman, Oklahoma area with the National Severe Storms Laboratory, and Mountain and desert turbulence in the Edwards Air Force Base, California area. Flight data are presented from flights which encountered the wind shear, turbulence and microburst anomalies. These flight results are discussed and some conclusions are made relating to these atmospheric anomalies.
A flight test program of a low cost, low speed, manned, oblique wing research airplane was conducted at the NASA Dryden Flight Research Facility in cooperation with NASA Ames Research Center between 1979 and 1982. When the principal purpose of the test program was completed, which was to demonstrate the flight and handling characteristics of the configuration, particularly in wing-sweep-angle ranges from 45 to 60 deg, a pilot evaluation program was conducted to obtain a qualification evaluation of the flying qualities of an oblique wing aircraft. These results were documented for use in future studies of such aircraft.
Plots of winds encountered in-flight are presented for a severe turbulence case from JAWS flight 7 (near Denver on the afternoon of July 15, 1982). During the flight the B-57B showed a 30-knot increase in airspeed over a distance of about 426 ft and then a more gradual decrease of 40 to 50 knots over a distance of about 3.2 miles. This suspected outflow feature was associated with downdraft in excess of 20 knots. The horizontal wind direction changed almost 180 deg during the pass through the feature, and the intensity of velocity differences decreased for all three components within the downdraft. Calculated probability density functions for u, v, and w showed a jagged character; and distributions for Delta-u, Delta-v, and Delta-w were distinctly non-Gaussian. Based on skewness and kurtosis values, the data could probably best be modeled by a Pearson type VII (Student's t) distribution.
Some historical developments of flight testing of unique aircraft configurations by NASA and the military sector are documented. Several test aircraft are outlined including the M2-F1 (which was the first Space Shuttle concept ever demonstrated, and contributed to the present design), the X-15, the Flying Wing, the Lunar Landing Research Vehicle, the Oblique Wing Research Aircraft, and the Space Shuttle Enterprise. Future test aircraft such as the forward swept wing X-29A Advanced Technology Demonstrator Aircraft, and the X-Wing vehicle are also mentioned. It is noted that the logical preliminary to flight testing is flight simulation, and that flight testing itself is the vital final component of the development, and seems to be the most direct approach to aircraft evaluations.
The Transonic Aircraft Technology (TACT) research program provided data necessary to verify aerodynamic concepts, such as the supercritical wing, and to gain the confidence required for the application of such technology to advanced high performance aircraft. An F-111A aircraft was employed as the flight test bed to provide full scale data. The data were correlated extensively with predictions based on data obtained from wind tunnel tests. An assessment of the improvement afforded at transonic speeds in drag divergence, maneuvering performance, and airplane handling qualities by the use of the supercritical wing was included in the program. Transonic flight and wind tunnel testing techniques were investigated, and specific research technologies evaluated were also summarized.
Advanced technical features of the electronic integrated propulsion control system (IPCS) and flight evaluation tests of IPCS (F-111E with TF30-P-9 engines as test vehicle) are described. Nine baseline flight tests and 15 IPCS flight tests were conducted. Instrumentation, data acquisition and data processing systems, software maintenance procedures, flight test procedures, flight safety criteria, flight test results, and ground and flight testing of the aircraft system are described. Advantages conferred by IPCS include: faster accelerations (both gas generator and afterburner performance), better thrust and flight control, reduced flight idle thrust, reduced engine ground trim, extended service ceiling, automatic stall detection, and stall recovery detection.
A flight evaluation was made of the mechanical hydraulic flight control system and the electrohydraulic stability augmentation system installed in the HL-10 lifting body research vehicle. Flight tests performed in the speed range from landing to a Mach number of 1.86 and the altitude range from 697 meters (2300 feet) to 27,550 meters (90,300 feet) were supplemented by ground tests to identify and correct structural resonance and limit-cycle problems. Severe limit-cycle and control sensitivity problems were encountered during the first flight. Stability augmentation system structural resonance electronic filters were modified to correct the limit-cycle problem. Several changes were made to control stick gearing to solve the control sensitivity problem. Satisfactory controllability was achieved by using a nonlinear system. A limit-cycle problem due to hydraulic fluid contamination was encountered during the first powered flight, but the problem did not recur after preflight operations were improved.
Performance criteria and test techniques are applied to stability augmentation systems (SAS) during ground testing to predict objectionable limit cycles and preclude structural resonance during flight. Factors that give rise to these problems, means of suppressing their effects, trade-offs to be considered, and ground test methods that have been developed are discussed. SAS performance predicted on the basis of these tests is compared with flight data obtained from three lifting body vehicles and the X-15 research airplane. Limit cycle and structural resonance test criteria, based upon ground and flight experience and data, were successfully applied to these vehicles. The criteria used were: The limit cycle amplitude (SAS gain multiplied by peak-to-peak angular rate) shall not exceed 0.5 deg for the highest product of control power and SAS gain that will be used in flight; the maximum in-flight SAS gain should never exceed 50 percent of the value at which a structural resonance can be sustained during ground test.
Lifting body stability augmentation systems design, development, ground tests and flight data including frequency response, limit cycle and structural resonance
M2-F2 lifting body flight control system
Air launch characteristics of M2-F2 lifting body from B-52 aircraft