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The AiResearch TFE731-2 Turbofan Engine Control system was created out of a recognition of engine and aircraft operating requirements in which a free weighting of candidate control components and logic was made. From this free design iteration process, which considered both conventional and advanced concepts of control, the control described in this paper has evolved and has fulfilled the in-flight operating requirements of the engine.

An automated nutrient replenishment system has been developed in order to provide a constant electrical conductivity (EC) value for the nutrient solution over the period of plant growth. A single nutrient film technique (NFT) system developed by the Tuskegee University NASA Center was equipped with the EC control system for growth trials with sweetpotatoes. The system is completely controlled and monitored by a PC through the use of LabView instrumentation and data acquisition software. A submersible EC probe driven by an EC controller measures the EC of the nutrient solution reservoir. EC values are passed from the controller to the PC through analog outputs. If the EC is outside a given range, the PC sends a signal to one of two solenoid valves that allow concentrated stock solution or deionized water to enter the reservoir to either raise or lower the EC respectively. For this application the set point is 1200μS cm-1, with a dead band from 1180 to 1220μS cm-1.

This paper reports the results of a program to develop a pneumatic actuation system for an experimental ejection seat trainer. The device was developed under contract to the U. S. Naval training Device Center, Port Washington, New York. A method of pneumatic open loop flow and pressure control is presented which results in predictable load dynamics during the ejection process. Close control of maximum rate of acceleration and maximum acceleration is obtained for a wide range of load weights. System analysis and individual component designs are discussed. Test data and calibration procedures are also presented. Although the present device is highly specialized, the design methods described in this paper are applicable to any high speed pneumatic ejection system requiring close control of load dynamics.

The Shuttle orbiter currently uses hydrazine-powered APU’s for powering its hydraulic system pumps. To enhance vehicle safety and reliability, NASA is pursuing an APU upgrade where the hydrazine-powered turbine is replaced by an electric motor pump and battery power supply. This EAPU (Electric APU) upgrade presents several thermal control challenges, most notably the new requirement for moderate temperature control of high-power electronics at 132 °F (55.6 °C). This paper describes how the existing Water Spray Boiler (WSB), which currently cools the hydraulic fluid and APU lubrication oil, is being modified to provide EAPU thermal management.

An optimization technique has been developed on the Flight Design System (FDS) which examines available target and instrument constraints to determine an optimal target launch time for maximum instrument viewing in a cooperative launch scenario. By definition, a cooperative launch is a coordinated mission between an orbiting viewing instrument and a target which is launched from the ground at a time specified by instrument viewing requirements. The technique is designed to evaluate instrument constraints such as range and slewing rate limitations and analyze them parametrically with the relative target launch time to determine the effect on the instrument viewing period. Using the FDS, this technique can be utilized in a real-time situation by updating the instrument's position and re-evaluating applicable parameters to obtain an updated target launch time.

Corrosion problems associated with using titanium fasteners to assemble aluminum airframe structures are reviewed. Data are presented describing the effectiveness of metallic platings and an aluminum filled organic based coating on fasteners to render the titanium-aluminum electrochemical couple inoperative. The aluminum enriched organic coating known as Hi-Kote 1 is shown to be more effective in minimizing corrosive attack on aluminum airframe structure in both saline and acidic environments. The effectiveness of Hi-Kote 1 in corrosion-fatigue tests of fastened aluminum structure is also reported.

Despite the increasing use of carbon fibre reinforced plastic (CFRP) composites, titanium and aluminium alloys still constitute a significant proportion of modern civil aircraft structures, which are primarily assembled via mechanical joining techniques. Drilling of fastening holes is therefore a critical operation, which has to meet stringent geometric tolerance and integrity criteria. The paper details the development of a three-dimensional (3D) finite element (FE) model for drilling aerospace grade aluminium (AA7010-T7451 and AA2024-T351) and titanium (Ti-6Al-4V) alloys. The FE simulation employed a Coupled Eulerian Lagrangian (CEL) technique. The cutting tool was modelled according to a Lagrangian formulation in which the mesh follows the material displacement while the workpiece was represented by a non-translating and material deformation independent Eulerian mesh.

The system that will be presented consists of a Crawling Portable Robot (CPR) for drilling large air frame components as a part of the whole assembly process of fuselage or wing type sub-structures. Currently, the drilling of such components is massively fulfilled manually in a very labour intensive and “craft-based” manner. The operations are conducted in cramped, dangerous conditions and often involve unhealthy postures. The alternative to this situation consists in the use of large fixed-base multi-axis machines mounted upon a foundation on the shop floor. These machines are quite expensive, and also have a number of operational limitations. Because of their large working envelope, it is difficult for these machines to hold close tolerances over the entire range of all movement axes of the machine. Hence, there is a need to probe and calibrate the machine to the workpiece one or more times during work operations with the consequent negative impact in productivity.

This paper describes a life support and EVA system for an SSTO that will have minimum mass impact on spaceship design while permitting full in-flight functionality, ready EVA, adequate back-up in emergencies and simplified maintenance and checkout. The system premises a single crewmember, continuously suited operations, limited on-orbit stay, an unpressurized cabin and EVA without need for an airlock. Conceptual drawing and mass estimate are provided.

Past weapon system support programs are criticized for lack of objectivity as evidenced by low equipment effectiveness. Management organization of the support effort is not functionally compatible with the weapons system philosophy. Its status should be equal to that of weapon design. A hypothetical operation analysis is reviewed and it is shown that many maintenance oriented inferences can be drawn from such data. A special point is made of the significance of elapsed time requirements for maintenance in combat operations. MIL-M-26512B is recommended as a means for providing quantitative maintenance time information as a system design criteria. Some shortcomings of MIL-M-26512B are pointed out, and new tables for performing maintainability analysis are illustrated and reviewed.

It is logistically unfeasible to supply the crew of a long-term space mission with earth-borne food-products only. Thus, in order to provide sufficient food for space missions exceeding one year, it is necessary to implement a plant breeding system on board, which can at least partly cover the crew’s nutritional needs. In the frame of a European Space Agency (ESA) feasibility study on Closed Loop Food Systems (CLFS) for Low Earth Orbit (LEO), Transit to Mars and Mars Surface scenarios, a nutrition selection algorithm was developed to define well equilibrated and diverse menus able to meet dietary requirements. First, an extensive, diversified crop list was compiled from a broad range of literature sources. Secondly, a database was constructed, containing all gathered information for the selected crops. In the scope of this ESA project, follow-up studies on plant growth chamber design and Equivalent System Mass (ESM) analysis were carried out.

For auxiliary power system applications in space, a cryogenic, positive-displacement power system has been developed. This system consists of an internal combustion engine using hydrogen as the fuel and oxygen as the oxidizer. This type of engine offers the lowest fixed weight of any space power unit under current development and provides for a very low specific propellant combustion. The engine, in turn, would provide electric and hydraulic power sources.

Fuel gaging systems in over 90% of small civil aircraft use the automotive float type sender with an electrical indicator. Considering such factors as dihedral, summing, temperature, variation in specific gravity of fuel used, and input voltage, the accuracy is approximately ±5% of full scale and ±10% of the reading. A more accurate system is highly desirable for weight control, flight planning, and possible c. g. consideration. Among other gaging systems available are improved float types at moderate costs, capacitive systems with good accuracy at comparatively high initial cost and increased maintenance, and a mass sensing system at moderate cost. The pros and cons of each system are discussed. Factors contributing to errors in readout and often overlooked are variations in height versus volume of fuel tanks because of manufacturing tolerances, and changes in shape and relative position of tanks under different loading when in flight.

An architecture is proposed for on-demand rapid commuting across congested-traffic areas. A lighter-than-air (LTA) vehicle provides the efficient loitering and part of the lift, while a set of cycloidal rotors provides the lift for payload as well as propulsion. This combination offers low noise and low downwash. A standardized automobile carriage is slung below the LTA, permitting driveway to driveway boarding and off-loading for a luxury automobile. The concept exploration is described, converging to the above system. The 6-DOF aerodynamic load map of the carriage is acquired using the Continuous-Rotation method in a wind tunnel. An initial design with rear ramp access is modified to have ramps at both ends. The initial design shows a divergence sped in access of 100 mph. An effort to improve the ride quality using yaw stabilizers, failed as the dynamic behavior becomes unstable. The requirements for control surfaces and instrumentation are discussed.

Details of the design and development of an airborne data acquisition system for in-flight evaluation of airfoils are presented. The system was designed to be flown aboard a single engine general aviation aircraft and to measure and record airfoil surface pressures, airfoil wake pressures, and aircraft angle of attack and airspeed. Included are descriptions of the instrumentation, calibration and data reduction techniques, illustrations of the raw data and comments on the operational experience gained during the flight evaluation of the GA(W)-2 airfoil.

An analytical procedure for the design of thermocouple probes for the accurate measurement of gas temperatures under steady state conditions is presented. Basic heat transfer concepts are used in the design of the probe envelope to provide an environment for the junction which is conducive to accurate gas temperature measurement. The procedure is illustrated by the design of a probe for measuring gas temperature in the range of 100°F with an error limit of 0.2°F at Mach numbers ranging from 0.2 to 1.0. Test results from this probe show a maximum error of 0.18°F, substantiating the design procedures.