Search NASA⌕ Search

SEARCH · Search NASA

Results for “PITCH ATTITUDE”

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.

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Pitch attitude, flight path, and airspeed control during approach and landing of a powered lift STOL aircraft

Analytical investigations and piloted moving base simulator evaluations were conducted for manual control of pitch attitude, flight path, and airspeed for the approach and landing of a powered lift jet STOL aircraft. Flight path and speed response characteristics were described analytically and were evaluated for the simulation experiments which were carried out on a large motion simulator. The response characteristics were selected and evaluated for a specified path and speed control technique. These charcteristics were: (1) the initial pitch response and steady pitch rate sensitivity for control of attitude with a pitch rate command/ attitude hold system, (2) the initial flight path response, flight path overshoot, and flight path-airspeed coupling in response to a change in thrust, and (3) the sensitivity of airspeed to pitch attitude changes. Results are presented in the form of pilot opinion ratings and commentary, substantiated where appropriate by response time histories and aircraft states at the point of touchdown.

Franklin, J. A.↗
NASA NTRS1990

A proposed definition for a pitch attitude target for the microburst escape maneuver

The Windshear Training Aid promulgated by the Federal Aviation Administration (FAA) defines the practical recovery maneuver following a microburst encounter as application of maximum thrust accompanied by rotation to an aircraft-specific target pitch attitude. In search of a simple method of determining this target, appropriate to a variety of aircraft types, a computer simulation was used to explore the suitability of a pitch target equal in numerical value to that of the angle of attack associated with stall warning. For the configurations and critical microburst shears simulated, this pitch target was demonstrated to be close to optimum.

Bray, Richard S.↗
NASA NTRS1973

In-flight measured human pilot describing function and remnant for pitch attitude control

Flight tests have been performed with a variable pitch-rate-command/attitude-hold flight control system in a Beechoraft Queen air-80 aircraft. Some results of in-flight measured runs for two pilots controlling typical easy and difficult dynamics are presented together with the initial results of the same tracking experiment performed on a ground-based flight simulator. Results are compared with results of other investigators using fixed-base flight simulators.

Mooij, H. A.↗
NASA NTRS1976

A parametric analysis of visual approaches for helicopters

A flight investigation was conducted to determine the characteristic shapes of the altitude, ground speed, and deceleration profiles of visual approaches for helicopters. Two hundred thirty-six visual approaches were flown from nine sets of initial conditions with four types of helicopters. Mathematical relationships were developed that describe the characteristic visual deceleration profiles. These mathematical relationships were expanded to develop equations which define the corresponding nominal ground speed, pitch attitude, pitch rate, and pitch acceleration profiles. Results are applicable to improved helicopter handling qualities in terminal area operations.

Moen, G. C.↗
NASA NTRS1981

Flight test evaluation of advanced symbology for general aviation approach to landing displays

This paper describes a set of flight test experiments which were designed to evaluate the relative utility of candidate displays with advanced symbology for General Aviation IFR operations in the terminal area. This symbology was previously evaluated as part of the NASA Langley Research Center's Terminal Configured Vehicle Program for use in commercial airlines. The advanced symbology included vehicle track-angle, flight path angle and a perspective representation of the runway. These symbols were selectively drawn on a CRT display along with the roll attitude, pitch attitude, localizer-deviation and glideslope deviation. In addition to the CRT display, the instrument panel contained standard turn and bank, altimeter, rate of climb, airspeed, heading and engine instruments. The symbology was evaluated using tracking performance and pilot subjective ratings for an ILS capture and tracking task.

Downing, D. R.↗
NASA NTRS1983

Advanced symbology for general aviation approach to landing displays

A set of flight tests designed to evaluate the relative utility of candidate displays with advanced symbology for general aviation terminal area instrument flight rules operations are discussed. The symbology was previously evaluated as part of the NASA Langley Research Center's Terminal Configured Vehicle Program for use in commercial airlines. The advanced symbology included vehicle track angle, flight path angle and a perspective representation of the runway. These symbols were selectively drawn on a cathode ray tube (CRT) display along with the roll attitude, pitch attitude, localizer deviation and glideslope deviation. In addition to the CRT display, the instrument panel contained standard turn and bank, altimeter, rate of climb, airspeed, heading, and engine instruments. The symbology was evaluated using tracking performance and pilot subjective ratings for an instrument landing system capture and tracking task.

Bryant, W. H.↗
NASA NTRS1973

Takeoff certification considerations for large subsonic and supersonic transport airplanes using the Ames flight simulator for advanced aircraft

Data for use in development of takeoff airworthiness standards for new aircraft designs such as the supersonic transport (SST) and the large wide-body subsonic jet transport are provided. An advanced motion simulator was used to compare the performance and handling characteristics of three representative large jet transports during specific flight certification tasks. Existing regulatory constraints and methods for determining rotation speed were reviewed, and the effects on takeoff performance of variations in rotation speed, pitch attitude, and pitch attitude rate during the rotation maneuver were analyzed. A limited quantity of refused takeoff information was obtained. The aerodynamics, wing loading, and thrust-to-weight ratio of the subject SST resulted in takeoff speeds limited by climb (rather than lift-off) considerations. Take-off speeds based on U.S. subsonic transport requirements were found unacceptable because of the criticality of rotation-abuse effects on one-engine-inoperative climb performance. Adequate safety margin was provided by takeoff speeds based on proposed Anglo-French supersonic transport (TSS) criteria, with the limiting criterion being that takeoff safety speed be at least 1.15 times the one-engine-inoperative zero-rate-of-climb speed. Various observations related to SST certification are presented.

Snyder, C. T.↗
NASA NTRS1985

Simulation evaluation of display/FLIR concepts for low-altitude, terrain-following helicopter operations

A piloted simulation of three head-down display (HDD) concepts with flight-director guidance superimposed on forward-looking infrared (FLIR) imagery was performed to evaluate the task of low-level, terrain-following (TF), manual helicopter flight. The three display concepts were examined for the purpose of finding ways by which aircraft flight-attitude and command symbols and FLIR imagery could be integrated onto one instrument. In all cases, the FLIR imagery was centered on the flight-path vector of the aircraft. The three displays were then characterized by having: (1) pitch attitude conformal to the FLIR imagery; (2) pitch attitude conformal to the FLIR imagery, but with an increase in the scaling; and (3) pitch attitude nonconformal to the FLIR imagery with the same pitch scaling as in (2). The simulation was conducted on the Vertical Motion Simulator (VMS) at Ames Research Center, using NASA and Air Force test pilots. The pilots indicated that the nonconformal pitch attitude and FLIR display was the preferred way to display information because of the absence of pitch-attitude information on displays (1) and (2) during some portions of the operational flight envelope.

Swenson, H. N.↗
NASA NTRS1992

Target pitch angle for the microburst escape maneuver

Recovery performance of a commuter-type aircraft in a microburst encounter is studied using a constant-pitch-attitude strategy and flight path optimization. Results obtained indicate that the pitch attitude which maximized climb rate in a wind shear condition is strongly dependent on whether the aircraft is subjected to a horizontal shear or a downdraft. The pitch attitude which maximizes ground clearance depends on the altitude of the encounter, the strength of the microburst, and the initial position of the aircraft with respect to the downburst core. Best results are obtained at relatively low target pitch angles, in severe wind shear encounters at very low altitudes. A technique for maximizing ground clearance involves maintaining a low pitch attitude early in the encounter, followed by a gradual pitch-up that ceases when the wind shear has been excited.

Mulgund, Sandeep S.↗
NASA NTRS1973

Pitch paper pilot revisited

Two methods are described for predicting the handling qualities of an aircraft in pitch. Both methods are based on minimizing a pilot rating expression with respect to free pilot parameters. In one case the pilot rating expression was developed from a set of moving base simulation data. In the other case, the pilot rating expression was developed from a set of fixed base simulation data. In both cases pilot rating is primarily a function of pitch attitude and pitch rate; however, in the moving base case, the pilot rating is more sensitive to pitch rate than in the fixed base case. For each method, predicted pilot ratings and performance measures agree well with the measured data corresponding to that case. Both methods are used to predict pilot ratings for a set of flight test configurations and the results of the two methods agree to within one half a rating unit. The predicted ratings in both cases correlate well with the actual pilot ratings from the flight tests.

Arnold, J. D.↗
NASA NTRS1961

Design and Flight Tests of an Adaptive Control System Employing Normal-Acceleration Command

An adaptive control system employing normal-acceleration command has been designed with the aid of an analog computer and has been flight tested. The design of the system was based on the concept of using a mathematical model in combination with a high gain and a limiter. The study was undertaken to investigate the application of a system of this type to the task of maintaining nearly constant dynamic longitudinal response of a piloted airplane over the flight envelope without relying on air data measurements for gain adjustment. The range of flight conditions investigated was between Mach numbers of 0.36 and 1.15 and altitudes of 10,000 and 40,000 feet. The final adaptive system configuration was derived from analog computer tests, in which the physical airplane control system and much of the control circuitry were included in the loop. The method employed to generate the feedback signals resulted in a model whose characteristics varied somewhat with changes in flight condition. Flight results showed that the system limited the variation in longitudinal natural frequency of the adaptive airplane to about half that of the basic airplane and that, for the subsonic cases, the damping ratio was maintained between 0.56 and 0.69. The system also automatically compensated for the transonic trim change. Objectionable features of the system were an exaggerated sensitivity of pitch attitude to gust disturbances, abnormally large pitch attitude response for a given pilot input at low speeds, and an initial delay in normal-acceleration response to pilot control at all flight conditions. The adaptive system chatter of +/-0.05 to +/-0.10 of elevon at about 9 cycles per second (resulting in a maximum airplane normal-acceleration response of from +/-0.025 g to +/- 0.035 g) was considered by the pilots to be mildly objectionable but tolerable.

McNeill, Water E.↗
NASA NTRS1984

Optimal redesign study of the harm wing

The purpose of this project was to investigate the use of optimization techniques to improve the flutter margins of the HARM AGM-88A wing. The missile has four cruciform wings, located near mid-fuselage, that are actuated in pairs symmetrically and antisymmetrically to provide pitch, yaw, and roll control. The wings have a solid stainless steel forward section and a stainless steel crushed-honeycomb aft section. The wing restraint stiffness is dependent upon wing pitch amplitude and varies from a low value near neutral pitch attitude to a much higher value at off-neutral pitch attitudes, where aerodynamic loads lock out any free play in the control system. The most critical condition for flutter is the low-stiffness condition in which the wings are moved symmetrically. Although a tendency toward limit-cycle flutter is controlled in the current design by controller logic, wing redesign to improve this situation is attractive because it can be accomplished as a retrofit. In view of the exploratory nature of the study, it was decided to apply the optimization to a wing-only model, validated by comparison with results obtained by Texas Instruments (TI). Any wing designs that looked promising were to be evaluated at TI with more complicated models, including body modes. The optimization work was performed by McIntosh Structural Dynamics, Inc. (MSD) under a contract from TI.

Mcintosh, S. C., Jr.↗
NASA NTRS1973

The effects of an autopilot on airplane responses to turbulence with emphasis on tail loads

An analytical study has been made to assess the loads developed on the horizontal tail of an autopilot-controlled rigid airplane flying in one-dimensional atmospheric turbulence. The root-mean-square values of rigid-airframe responses and tail-load responses were calculated at five flight conditions, and the behavior of these responses was observed in two autopilot modes: pitch-attitude-hold mode and altitude-control mode. It was found that pitch attitude and altitude can be controlled by the simple autopilot with acceptable or no increases in tail loads.

Perry, B., III↗
NASA NTRS2017

Simulating the Impact Response of Three Full-Scale Crash Tests of Cessna 172 Aircraft

During the summer of 2015, a series of three full-scale crash tests were performed at the Landing and Impact Research Facility located at NASA Langley Research Center of Cessna 172 aircraft. The first test (Test 1) represented a flare-to-stall emergency or hard landing onto a rigid surface. The second test (Test 2) represented a controlled-flight- into-terrain (CFIT) with a nose down pitch attitude of the aircraft, which impacted onto soft soil. The third test (Test 3) also represented a CFIT with a nose up pitch attitude of the aircraft, which resulted in a tail strike condition. Test 3 was also conducted onto soft soil. These crash tests were performed for the purpose of evaluating the performance of Emergency Locator Transmitters and to generate impact test data for model calibration. Finite element models were generated and impact analyses were conducted to simulate the three impact conditions using the commercial nonlinear, transient dynamic finite element code, LS-DYNA®. The objective of this paper is to summarize test-analysis results for the three full-scale crash tests.

Jackson, Karen E.↗