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At least 1,297 records · Page 72
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Stall/spin flight results for the remotely piloted spin research vehicle

The unmanned, remotely piloted, unpowered, spin research vehicle was used to evaluate the effects of the nose boom and of a wind tunnel-designed nose strake on the vehicle's stall/spin characteristics. The flight-determined directional stability derivatives and the attempted spin entries indicated that the vehicle with a nose strake had increased resistance to departure and spin. The acquisition of high quality steady spin data for this vehicle was made possible by the remotely piloted technique. The zero control smooth spin modes were found to be highly repeatable for a given configuration and to vary with forebody configuration. Several spin recovery techniques, including a nose parachute, are also evaluated.

Iliff, K. W.↗
NASA NTRS1981

The DAST-1 remotely piloted research vehicle development and initial flight testing

The development and initial flight testing of the DAST (drones for aerodynamic and structural testing) remotely piloted research vehicle, fitted with the first aeroelastic research wing ARW-I are presented. The ARW-I is a swept supercritical wing, designed to exhibit flutter within the vehicle's flight envelope. An active flutter suppression system (FSS) designed to increase the ARW-I flutter boundary speed by 20 percent is described. The development of the FSS was based on prediction techniques of structural and unsteady aerodynamic characteristics. A description of the supporting ground facilities and aircraft systems involved in the remotely piloted research vehicle (RPRV) flight test technique is given. The design, specification, and testing of the remotely augmented vehicle system are presented. A summary of the preflight and flight test procedures associated with the RPRV operation is given. An evaluation of the blue streak test flight and the first and second ARW-I test flights is presented.

Kotsabasis, A.↗
NASA NTRS1981

The Aerospace Vehicle Interactive Design system

The aerospace vehicle interactive design (AVID) is a computer aided design that was developed for the conceptual and preliminary design of aerospace vehicles. The AVID system evolved from the application of several design approaches in an advanced concepts environment in which both mission requirements and vehicle configurations are continually changing. The basic AVID software facilitates the integration of independent analysis programs into a design system where the programs can be executed individually for analysis or executed in groups for design iterations and parametric studies. Programs integrated into an AVID system for launch vehicle design include geometry, aerodynamics, propulsion, flight performance, mass properties, and economics.

Wilhite, A. W.↗
NASA NTRS1980

Minimum fuel control of a vehicle with a continuously variable transmission

The design and evaluation of a control system for a sedan with a heat engine and a continuously variable transmission, is considered in a effort to minimize fuel consumption and achieve satisfactory dynamic response of vehicle variables as the vehicle is driven over a standard driving cycle. Even though the vehicle system was highly nonlinear, attention was restricted to linear control algorithms which could be easily understood and implemented demonstrated by simulation. Simulation results also revealed that the vehicle could exhibit unexpected dynamic behavior which must be taken into account in any control system design.

Burghart, J. H.↗
NASA NTRS1981

Vehicle concepts and technology requirements for buoyant heavy-lift systems

Several buoyant-vehicle (airship) concepts proposed for short hauls of heavy payloads are described. Numerous studies identified operating cost and payload capacity advantages relative to existing or proposed heavy-lift helicopters for such vehicles. Applications involving payloads of from 15 tons up to 800 tons were identified. The buoyant quad-rotor concept is discussed in detail, including the history of its development, current estimates of performance and economics, currently perceived technology requirements, and recent research and technology development. It is concluded that the buoyant quad-rotor, and possibly other buoyant vehicle concepts, has the potential of satisfying the market for very heavy vertical lift but that additional research and technology development are necessary. Because of uncertainties in analytical prediction methods and small-scale experimental measurements, there is a strong need for large or full-scale experiments in ground test facilities and, ultimately, with a flight research vehicle.

Ardema, M. D.↗
NASA NTRS1980

High performance cryogenic engines for orbit transfer vehicles

Evaluations of O2/H2 engine candidates in the 10K to 30K lb thrust class for Manned Orbit Transfer Vehicles (MOTV) and engine candidates using O2/H2, O2/RP-1, and O2/CH4 in the 100 to 3,000 lb thrust range for Cargo Orbit Transfer Vehicles (COTV) are discussed. Both space vehicles are part of the larger SPS concept. It is shown that the Advanced Expander Cycle O2/H2 engine for MOTV merits further study and investigations. COTV engine study has so far indicated that conventionally cooled O2/H2 and O2/CH4 engine candidates should be evaluated further, while advanced cooling schemes are required for O2/RP-1 concepts. With regard to MOTV, it is concluded that while no existing system meets the requirements of the Orbit Transfer Vehicles, the need for twin expander cycle engines is established because a single engine cannot provide a tolerable man-safety profile. With regard to COTV, it is stressed that advanced cooling concepts must be considered if other propellant combinations are to become competitive with O2/H2. Multistage centrifugal pumps are seen as the most promising concept.

Bassham, L. B.↗
NASA NTRS1981

Aerobraked orbital transfer vehicle definition

A new technique has been developed to enhance the use of upper atmosphere aerobraking for increased performance from orbital transfer vehicles. This technique utilizes a pressure supported drag brake and the orbital transfer vehicle main engine to modulate aerodynamic drag and also to alleviate the aerodynamic heating during a grazing pass through the atmosphere. Performance analyses of vehicles utilizing all-propulsive or aerobraking during round trip missions from low earth orbit (LEO) to geo-synchronous earth orbit (GEO) and back shows that aerobraking allows a given vehicle to deliver approximately twice as much payload to GEO and return. Aerobraking also provides more than twice the round trip payload.

Andrews, D. G.↗
NASA NTRS1981

The Aerospace Vehicle Interactive Design system

The Aerospace Vehicle Interactive Design (AVID) is a computer-aided design system that was developed for the conceptual and preliminary design of aerospace vehicles. The AVID system evolved from the application of several design approaches in an advanced concepts environment in which both mission requirements and vehicle configurations are continually changing. The basic AVID software facilitates the integration of independent analysis programs into a design system where the programs can be executed individually for analysis or executed in groups for design iterations and parametric studies. Programs that have been integrated into an AVID system for launch vehicle design include geometry, aerodynamics, propulsion, flight performance, mass properties, and economics.

Wilhite, A. W.↗
NASA NTRS1981

Orbital transfer vehicle - An overview

A summary is given of the concept definition phase of NASA's Orbital Transfer Vehicle (OTV) program. The mission requirements are threefold: (1) the ability to deliver payloads well beyond the capability of any current system at low acceleration levels, (2) the extension of the cost effectiveness from reusability and operational flexibility provided by the Shuttle at LEO to the geosynchronous altitude, and (3) the provision of the round trip capability needed to service and maintain this expanded and more valuable resource at GEO. The initial Shuttle-matched, reusable OTV is shown to be cost effective with low development cost, relatively short development period and high projected reliability. The performance enhancement provided by aero-assist is discussed, which will enable the difficult round trip to be flown in a single Shuttle launch. Two methods of reducing vehicle velocity are available: (1) aeromaneuvering, which uses vehicle lift to climb or descend and thereby correct for density variations, and (2) aerobraking which varies vehicle drag directly to correct for density.

Caluori, V. A.↗
NASA NTRS1982

Vehicle test report: Battronic pickup truck

An electric pickup truck was tested to characterize certain parameters and to provide baseline data that can be used for the comparison of improved batteries that may be incorporated into the vehicle at a later time. The vehicle tests were concentrated on the electrical drive subsystem; i.e., the batteries, controller, and motor. The tests included coastdowns to characterize the road load and range evaluations for both cyclic and constant speed conditions. A qualitative evaluation of the vehicle's performance was made by comparing its constant speed range performance with other vehicles.

Price, T. W.↗
NASA NTRS1982

A study of flight control requirements for advanced, winged, earth-to-orbit vehicles with far-aft center-of-gravity locations

Control requirements of Controlled Configured Design Approach vehicles with far-aft center of gravity locations are studied. The baseline system investigated is a fully reusable vertical takeoff/horizontal landing single stage-to-orbit vehicle with mission requirements similar to that of the space shuttle vehicle. Evaluations were made to determine dynamic stability boundaries, time responses, trim control, operational center-of-gravity limits, and flight control subsystem design requirements. Study tasks included a baseline vehicle analysis, an aft center of gravity study, a payload size study, and a technology assessment.

Hepler, A. K.↗
NASA NTRS1982

Vehicle test report: Jet Industries Electra Van 600

The Electra Van 600, an electric vehicle, was tested. Tests were performed to characterize parameters of the Electra Van 600 and to provide baseline data to be used for comparison of improved batteries and to which will be incorporated into the vehicle. The vehicle tests concentrated on the electrical drive subsystem, the batteries, controller, and motor; coastdowns to characterize the road load and range evaluation for cyclic and constant speed conditions; and qualitative performance was evaluated. It is found that the Electra Van 600 range performance is approximately equal to the majority of the vehicles tested previously.

Price, T. W.↗
NASA NTRS1982

Rolling resistance of electric vehicle tires from track tests

Special low-rolling-resistance tires were made for DOE's ETV-1 electric vehicle. Tests were conducted on these tires and on a set of standard commercial automotive tires to determine the rolling resistance as a function of time during both constant-speed tires and SAE J227a driving cycle tests. The tests were conducted on a test track at ambient temperatures that ranged from 15 to 32 C (59 to 89 F) and with tire pressures of 207 to 276 kPa (30 to 40 psi). At a contained-air temperature of 38 C (100 F) and a pressure of 207 kPa (30 psi) the rolling resistances of the electric vehicle tires and the standard commercial tires, respectively, were 0.0102 and 0.0088 kilogram per kilogram of vehicle weight. At a contained-air temperature of 38 C (100 F) and a pressure of 276 kPa (40 psi) the rolling resistances were 0.009 and 0.0074 kilogram per kilogram of vehicle weight, respectively.

Dustin, M. O.↗
NASA NTRS1982

Progress on advanced dc and ac induction drives for electric vehicles

Progress is reported in the development of complete electric vehicle propulsion systems, and the results of tests on the Road Load Simulator of two such systems representative of advanced dc and ac drive technology are presented. One is the system used in the DOE's ETV-1 integrated test vehicle which consists of a shunt wound dc traction motor under microprocessor control using a transistorized controller. The motor drives the vehicle through a fixed ratio transmission. The second system uses an ac induction motor controlled by transistorized pulse width modulated inverter which drives through a two speed automatically shifted transmission. The inverter and transmission both operate under the control of a microprocessor. The characteristics of these systems are also compared with the propulsion system technology available in vehicles being manufactured at the inception of the DOE program and with an advanced, highly integrated propulsion system upon which technology development was recently initiated.

Schwartz, H. J.↗
NASA NTRS1982

Optimum wing sizing of a single-stage-to-orbit vehicle

An investigation has been conducted to determine preliminary wing designs for a single-stage-to-orbit (SSTO) vehicle. This vehicle has the following mission profile: vertical takeoff, boost-to-orbit, hypersonic reentry, and horizontal landing. For this vehicle, the wing is sized to meet Space Shuttle reentry aerodynamic requirements for hypersonic trim and horizontal landing, since reentry trajectories for the Shuttle and the SSTO vehicle are similar. A hypersonic and subsonic aerodynamic computer program was developed and combined with an existing optimization algorithm to automatically size and shape a wing which satisfies both reentry and landing requirements while also maintaining a minimum mass design. With this procedure, the influence of hypersonic and subsonic aerodynamic requirements, control surface size, and center-of-gravity positions on the initial wing design were investigated.

Wilhite, A. W.↗
NASA NTRS1982

Automated mixed traffic vehicle design AMTV 2

The design of an improved and enclosed Automated Mixed Traffic Transit (AMTT) vehicle is described. AMTT is an innovative concept for low-speed tram-type transit in which suitable vehicles are equipped with sensors and controls to permit them to operate in an automated mode on existing road or walkway surfaces. The vehicle chassis and body design are presented in terms of sketches and photographs. The functional design of the sensing and control system is presented, and modifications which could be made to the baseline design for improved performance, in particular to incorporate a 20-mph capability, are also discussed. The vehicle system is described at the block-diagram-level of detail. Specifications and parameter values are given where available.

Johnston, A. R.↗
NASA NTRS1982

Improved SCR ac Motor Controller for Battery Powered Urban Electric Vehicles

An improved ac motor controller, which when coupled to a standard ac induction motor and a dc propulsion battery would provide a complete electric vehicle power train with the exception of the mechanical transmission and drive wheels was designed. In such a system, the motor controller converts the dc electrical power available at the battery terminals to ac electrical power for the induction motor in response to the drivers commands. The performance requirements of a hypothetical electric vehicle with an upper weight bound of 1590 kg (3500 lb) were used to determine the power rating of the controller. Vehicle acceleration capability, top speed, and gradeability requisites were contained in the Society of Automotive Engineers (SAE) Schedule 227a(d) driving cycle. The important capabilities contained in this driving cycle are a vehicle acceleration requirement of 0 to 72.4 kmph (0 to 45 mph) in 28 seconds a top speed of 88.5 kmph (55 mph), and the ability to negotiate a 10% grade at 48 kmph (30 mph). A 10% grade is defined as one foot of vertical rise per 10 feet of horizontal distance.

Latos, T. S.↗
NASA NTRS1983

Vehicle charging and potential on the STS-3 mission

An electron gun with fast pulse capability was used in the vehicle charging and potential experiment carried on the OSS-1 pallet to study dielectric charging, return current mechanisms, and the techniques required to manage the electrical charging of the orbiter. Return currents and charging of the dielectrics were measured during electron beam emission and plasma characteristics in the payload bay were determined in the absence of electron beam emission. The fast pulse electron generator, charge current probes, spherical retarding potential analyzer, and the digital control interface unit which comprise the experiment are described. Results show that the thrusters produce disturbances which are variable in character and magnitude. Strong ram/wake effects were seen in the ion densities in the bay. Vehicle potentials are variable with respect to the plasma and depend upon location on the vehicle relative to the main engine nozzles, the vehicle attitude, and the direction of the geomagnetic field.

Williamson, R.↗