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At least 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

An MBSE Framework to Identify Regulatory Gaps for Electrified Transport Aircraft

A typical aircraft certification process consists of obtaining a type, production, airworthiness, and continued airworthiness certificates. During this process, a type certification plan is created that includes the intended regulatory operating environment, the proposed certification basis, means of compliance, and a list of documentation to show compliance. Earlier work by the authors demonstrated a model-based framework for the management of these certification artifacts for normal category airplanes. Presently, it is expanded and adapted to consider certification for transport category airplanes regulated under 14 CFR Part 25, providing clear transparency and traceability between the text of the regulations and imposed requirements, contextual information, and specified test activities. In particular, a capability to identify potential gaps in the applicability of regulations for novel architectures such as electrified aircraft is proposed. This capability, based on mismatches between the functional intent and the corresponding prescribed physical implementation, is developed. A sample implementation of the proposed capability is presented for a notional electrified powertrain aircraft architecture.

electrified transport aircraft↗
NASA NTRS1995

Effects of Nose Strakes On Transport Aircraft

A low-speed wind tunnel investigation was conducted in the Langley 12-Foot Tunnel on a typical commercial transport configuration to determine the effect of adding nose strakes on the aerodynamic characteristics of the model. The fuselage and wings of the model were scaled versions of the McDonnell-Douglas DC-9 aircraft. A generic tail assembly was employed that was different from that of the DC-9. Three different strake configurations were tested at several inclination angles. One strake configuration was identical to that employed on the DC-9 aircraft. The model was tested through a range of angles of attack and sideslip angles. Tests were made both with and without strakes and also with the vertical tail removed.

Locklear, Calvin T.↗
NASA NTRS1973

Preliminary weight and cost estimates for transport aircraft composite structural design concepts

Preliminary weight and cost estimates have been prepared for design concepts utilized for a transonic long range transport airframe with extensive applications of advanced composite materials. The design concepts, manufacturing approach, and anticipated details of manufacturing cost reflected in the composite airframe are substantially different from those found in conventional metal structure and offer further evidence of the advantages of advanced composite materials.

Source record↗
NASA NTRS1992

Experimental study of pylon geometries for transport aircraft

Pylon cross-sectional geometries that are intended to reduce propulsion system installation drag were investigated on a 1/17th-scale low-wing transport model in the NASA Langley 16-Foot Transonic Tunnel. The basic design philosophy for these pylons was to alleviate flow acceleration without introducing severe adverse pressure gradients near the pylon/wing junction. This was achieved by means of a gradually, diverging pylon with maximum thickness occurring at the wing trailing edge. The pylon closure occurs aft of the wing trailing edge. The force, surface pressure and surface flow visualization data obtained support this concept.

Naik, Dinesh A.↗
NASA NTRS1981

Transport aircraft flying qualities activities

The optimal control model for pilot vehicle systems was used to develop a methodology for predicting pilot ratings for commercial transports. The method was tested by applying it to a family of transport configurations for which subjective pilot ratings were obtained. Specific attention is given to the development of the simulator program and procedures so as to yield objective and subjective performance data useful for a critical evaluation of the analytical method.

Moul, M. T.↗
NASA NTRS1978

Evaluation of laminar flow control system concepts for subsonic commercial transport aircraft

A two-year study conducted to establish a basis for industry decisions on the application of laminar flow control (LFC) to future commercial transports was presented. Areas of investigation included: (1) mission definition and baseline selection; (2) concepts evaluations; and (3) LFC transport configuration selection and component design. The development and evaluation of competing design concepts was conducted in the areas of aerodynamics, structures and materials, and systems. The results of supporting wind tunnel and laboratory testing on a full-scale LFC wing panel, suction surface opening concepts and structural samples were included. A final LFC transport was configured in incorporating the results of concept evaluation studies and potential performance improvements were assessed. Remaining problems together with recommendations for future research are discussed.

Source record↗
NASA NTRS1984

Technology developments for laminar boundary layer control on subsonic transport aircraft

An overview of laminar flow control (LFC) technology developments is presented, along with a description of NASA's broadened program concerning laminar flow concepts for commercial transports. Topics covered include developments in LFC airfoils, wing surface panels, and leading-edge systems, as well as the effects of high altitude ice particles and insect impacts. It is suggested that the electron beam perforated titanium surface is superior to the Dynapore surface. The Douglas LFC wing design, the Krueger flap, the Lockheed, and the Douglas leading-edge concepts are covered. Future research includes an evaluation of a hybrid LFC concept, which combines LFC suction in the leading-edge region with natural laminar flow over the wing box.

Wagner, R. D.↗
NASA NTRS1995

Design, analysis, and control of a large transport aircraft utilizing selective engine thrust as a backup system for the primary flight control

A study has been conducted to determine the capability to control a very large transport airplane with engine thrust. This study consisted of the design of an 800-passenger airplane with a range of 5000 nautical miles design and evaluation of a flight control system, and design and piloted simulation evaluation of a thrust-only backup flight control system. Location of the four wing-mounted engines was varied to optimize the propulsive control capability, and the time constant of the engine response was studied. The goal was to provide level 1 flying qualities. The engine location and engine time constant did not have a large effect on the control capability. The airplane design did meet level 1 flying qualities based on frequencies, damping ratios, and time constants in the longitudinal and lateral-directional modes. Project pilots consistently rated the flying qualities as either level 1 or level 2 based on Cooper-Harper ratings. However, because of the limited control forces and moments, the airplane design fell short of meeting the time required to achieve a 30 deg bank and the time required to respond a control input.

Gerren, Donna S.↗
NASA NTRS1999

Additional Development and Systems Analyses of Pneumatic Technology for High Speed Civil Transport Aircraft

In the Task I portion of this NASA research grant, configuration development and experimental investigations have been conducted on a series of pneumatic high-lift and control surface devices applied to a generic High Speed Civil Transport (HSCT) model configuration to determine their potential for improved aerodynamic performance, plus stability and control of higher performance aircraft. These investigations were intended to optimize pneumatic lift and drag performance; provide adequate control and longitudinal stability; reduce separation flowfields at high angle of attack; increase takeoff/climbout lift-to-drag ratios; and reduce system complexity and weight. Experimental aerodynamic evaluations were performed on a semi-span HSCT generic model with improved fuselage fineness ratio and with interchangeable plain flaps, blown flaps, pneumatic Circulation Control Wing (CCW) high-lift configurations, plain and blown canards, a novel Circulation Control (CC) cylinder blown canard, and a clean cruise wing for reference. Conventional tail power was also investigated for longitudinal trim capability. Also evaluated was unsteady pulsed blowing of the wing high-lift system to determine if reduced pulsed mass flow rates and blowing requirements could be made to yield the same lift as that resulting from steady-state blowing. Depending on the pulsing frequency applied, reduced mass flow rates were indeed found able to provide lift augmentation at lesser blowing values than for the steady conditions. Significant improvements in the aerodynamic characteristics leading to improved performance and stability/control were identified, and the various components were compared to evaluate the pneumatic potential of each. Aerodynamic results were provided to the Georgia Tech Aerospace System Design Lab. to conduct the companion system analyses and feasibility study (Task 2) of theses concepts applied to an operational advanced HSCT aircraft. Results and conclusions from these experimental evaluations are presented herein, as are recommendations for further development and follow-on investigations. Also provided as an Appendix for reference are the basic results from the previous pneumatic HSCT investigations.

Englar, Robert J.↗
NASA NTRS1974

Vehicle design considerations for active control application to subsonic transport aircraft

The state of the art in active control technology is summarized. How current design criteria and airworthiness regulations might restrict application of this emerging technology to subsonic CTOL transports of the 1980's are discussed. Facets of active control technology considered are: (1) augmentation of relaxed inherent stability; (2) center-of-gravity control; (3) ride quality control; (4) load control; (5) flutter control; (6) envelope limiting, and (7) pilot interface with the control system. A summary and appraisal of the current state of the art, design criteria, and recommended practices, as well as a projection of the risk in applying each of these facets of active control technology is given. A summary of pertinent literature and technical expansions is included.

Hofmann, L. G.↗
NASA NTRS1980

Simulated vortex encounters by a twin-engine commercial transport aircraft during final approach

Piloted simulations of encounters with vortices of various ages and degrees of attenuation were performed with the Visual Motion Simulator. In the simulations, a twin-engine, commercial transport on final approach encountered the modeled vortices of a four-engine, wide-body, commercial transport. The data in this report show the effect of vortex age and ground effect on the severity of the initial upset, as well as the effect of the vortex encounters on the landing capability.

Hastings, E. C., Jr.↗
NASA NTRS1974

A parametric analysis of transport aircraft system weights and costs

In determining unit and operating costs for advanced aircraft, it has been found that by having first-order weight and performance approximations for the aircraft systems and structural components, a step increase in cost prediction accuracy results. This paper presents first-order approximation equations for these systems and components. These equations were developed from data for most current jet transports, and they have been ordered to use a minimum number of performance parameters such as aircraft style, number of passengers, empty and gross weight, cargo load, and operating range. A NASA Ames Research Center aircraft cost program has been used to compare calculated and actual weights for the same aircraft. Good aircraft cost correlation is shown to exist between calculated first-order and actual aircraft weight data.

Anderson, J. L.↗
NASA NTRS1980

Numerical optimization - An assessment of its role in transport aircraft aerodynamic design through a case study

An efficient transonic wing design procedure based upon numerical optimization together with three-dimensional transonic methods has been developed and used to design an advanced transport wing. The method development included an examination of the use of both full potential and extended small disturbance analysis codes and demonstrated that the former formulation was more reliable. In either case, the design procedure is economical and easy to use. Design verification in a unique semi-span test arrangement demonstrated that the design method produced a wing which satisfied the study design requirements. However, aeroelastic deformation of the wing occurred during the wind tunnel test. The computational methods used in the design procedure were employed to assess the effect of the aeroelastic deformation. The paper concludes with an evaluation of the design procedure and recommendation for its improvement.

Lores, M. E.↗
NASA NTRS2008

A Piloted Simulator Evaluation of Transport Aircraft Rudder Pedal Force/Feel Characteristics

A piloted simulation study has been conducted in a fixed-base research simulator to assess the directional handling qualities for various rudder pedal feel characteristics for commercial transport airplanes. That is, the effects of static pedal force at maximum pedal travel, breakout force, and maximum pedal travel on handling qualities were studied. An artificial maneuver with a severe lateral wind shear and requiring runway tracking at an altitude of 50 feet in a crosswind was used to fully exercise the rudder pedals. Twelve active airline pilots voluntarily participated in the study and flew approximately 500 maneuvers. The pilots rated the maneuver performance with various rudder pedal feel characteristics using the Cooper- Harper rating scale. The test matrix had 15 unique combinations of the 3 static pedal feel characteristics. A 10-term, second-order equation for the Cooper-Harper pilot rating as a function of the 3 independent pedal feel parameters was fit to the data. The test matrix utilized a Central Composite Design that is very efficient for fitting an equation of this form. The equation was used to produce contour plots of constant pilot ratings as a function of two of the parameters with the third parameter held constant. These contour plots showed regions of good handling qualities as well as regions of degraded handling qualities. In addition, a numerical equation solver was used to predict the optimum parameter values (those with the lowest pilot rating). Quantitative pilot performance data were also analyzed. This analysis found that the peak values of the cross power spectra of the pedal force and heading angle could be used to quantify the tendency toward directional pilot induced oscillations (PIO). Larger peak values of the cross power spectra were correlated with larger (degraded) Cooper-Harper pilot ratings. Thus, the subjective data (Cooper-Harper pilot ratings) were consistent with the objective data (peak values of the cross power spectra).

Stewart, Eric C.↗
NASA NTRS1988

Flight test experience and controlled impact of a remotely piloted jet transport aircraft

The Dryden Flight Research Center Facility of NASA Ames Research Center (Ames-Dryden) and the FAA conducted the controlled impact demonstration (CID) program using a large, four-engine, remotely piloted jet transport airplane. Closed-loop primary flight was controlled through the existing onboard PB-20D autopilot which had been modified for the CID program. Uplink commands were sent from a ground-based cockpit and digital computer in conjunction with an up-down telemetry link. These uplink commands were received aboard the airplane and transferred through uplink interface systems to the modified PB-20D autopilot. Both proportional and discrete commands were produced by the ground system. Prior to flight tests, extensive simulation was conducted during the development of ground-based digital control laws. The control laws included primary control, secondary control, and racetrack and final approach guidance. Extensive ground checks were performed on all remotely piloted systems; however, piloted flight tests were the primary method and validation of control law concepts developed from simulation. The design, development, and flight testing of control laws and systems required to accomplish the remotely piloted mission are discussed.

Horton, Timothy W.↗
NASA NTRS1985

Advanced secondary power system for transport aircraft

A concept for an advanced aircraft power system was identified that uses 20-kHz, 440-V, sin-wave power distribution. This system was integrated with an electrically powered flight control system and with other aircraft systems requiring secondary power. The resulting all-electric secondary power configuration reduced the empty weight of a modern 200-passenger, twin-engine transport by 10 percent and the mission fuel by 9 percent.

Hoffman, A. C.↗
NASA NTRS1978

Studies of advanced transport aircraft

Several concepts for possible future airplanes, including all-wing distributed-load airplanes, multibody airplanes, a long-range laminar flow control airplane, a nuclear-powered airplane designed for towing conventionally powered airplanes during long-range cruise, and an aerial transportation system comprised of continuously flying liner airplanes operated in conjunction with short-range feeder airplanes are described. Performance and economic advantages of each concept are indicated. Further research is recommended in the following areas: all-wing airplane aerodynamics, aerial rendezvous, nuclear aircraft engines, air-cushion landing systems, and laminar flow control, as well as the basic research discipline areas of aerodynamics, structures, propulsion, avionics, and computer applications.

Nagel, A. L.↗