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Since the introduction of Electro-Chemical Machining some ten years ago, the process has been used to good advantage for the difficult machining operations where machinability and geometry posed difficult problems. With this success, the use of ECM has grown into areas of many conventional operations. The new concepts of better control, more accurate reliable machines, coupled with higher amperage power supplies, are putting this process on a competitive basis with normal milling operations. To promote the acceptance of this process in industry, not only have new concepts of the machine tool been executed but much work has gone into tool development, research on electrolytes and surface effects. Manufacturers now offer not only initial installation and training in your plant but also hold periodic formal training seminars and make tooling manuals available to their customers.

DC-8 aircraft fuel tank sump drainings and soil, air, and fuel-water samples from fuel distribution facilities were analyzed for microbial contamination. The data were evaluated to determine the fuel tank contamination, its sources, and its effect upon the aircraft so that corrosion prevention methods could be developed. Sampling plans and microbial examination techniques are presented. Principal contaminants were Hormodendrum resinae, Candida sp., and yeastlike cells. They appeared together in many aircraft. Most of the microorganisms found in aircraft samples were also found in samples from fuel distribution facilities, but only in very low frequency in aircraft dispensed fuel. The fuel facilities could serve as an important microbial source when the final barrier is breached or not effective.

An investigation of fuel additives was conducted to identify materials which will reduce or eliminate jet engine exhaust smoke. Many materials were evaluated in a full-scale combustor rig, and the better ones were further tested in full-scale engines, both on the ground and in flight. Several additives were found capable of essentially eliminating smoke under some conditions. Although all of them formed solid exhaust products, in some cases these products caused no major adverse effects on J79 engine operation in limited endurance tests.

The purpose of this paper is to show how an airline sees the SST engines from the 1967 perspective. With the British-French Concorde only months away from first flight, and the major United States SST design decisions made, the age of commercial supersonic flight has practically arrived. Afterburning turbojets will provide the power for both transport airplanes. A review is made, therefore, of some of the technological and operational complications which face the users of this equipment. Among these are the questions of how to deal with the noise problem, what the new higher engine operating temperatures will mean, and what might need to be done in the event of a performance “bust” of the airplane-engine combination. An attempt is made to identify the real problems and separate them from the imaginary ones: finally, the review ends on an optimistic note considering the resources and creative problem solving abilities of the industry itself.

Metal-matrix composites of aluminum, titanium, nickel and their alloys reinforced by continuous filaments of boron or silicon carbide are considered. The aluminum-boron system provides advantages at temperatures to 600 F for general application; the titanium-silicon carbide system shows promise for high-temperature applications;but the nickel-silicon carbide system presents problems in compatibility between the two materials at high temperatures. Selection of matrix alloys depends on filament loading, thermal history imposed by fabrication and usage requirements, the composite reinforcement geometry, and the nature of-stress distribution resulting from external loadings.

Pivot point concepts for fighter type aircraft with variable sweep wings are reviewed. Structural and aerodynamic considerations involved in sweep pivot location, a summary of endurance testing of Teflon lined journal bearings, and variation of fatigue life of the aircraft versus wing sweep position are discussed.

Aircraft designs have been characterized by an increasing utilization of variable geometry features as aircraft capabilities expand into new flight regimes. The trend seems likely to continue as requirements for new aircraft become continually more demanding. The successful application of variable geometry depends on several things: the understanding of the aerodynamic principles involved, efficient structure, and whether an overall worthwhile improvementin performance, maneuverability, or flying qualities is gained; since it certainly will cost more, be less reliable, and more difficult to maintain. The application of some existing and proposed variable geometry schemes to aircraft is discussed. The aerodynamic factors affecting low and high speed performance, maneuverability, and stability and control characteristics indicate some of the desirable and troublesome aspects of these concepts.

This paper discusses some of the more significant factors which affect the design and flying qualities of a variable geometry aircraft. These comments were prepared by a test pilot currently involved in testing a variable geometry aircraft and are not as detailed as one might expect from a design engineer's viewpoint. The selection of a wing pivot location is discussed along with longitudinal stability characteristics. The comments on flying qualities of a variable wing aircraft include trim changes and buffet boundary limits with wing sweeps, performance gains, operational flexibility, and cockpit controls. In addition, some suggestions for future application of the variable geometry principles are made.

The variable-geometry features of the United States supersonic transport are described. Particular attention is given to the hardware development of those variable-geometry features unique to the supersonic transport. The design, development, and current status of a direct lift control sys tern, the supersonic internal-external compression inlet, and the full-scale wing pivot are described.

The aerodynamic features of the C-5A discussed will include only those items which posed a significant challenge to the aerodynamicist: airfoil sections, high lift systems, and control and augmentation systems. While the cruise configuration is quite conventional in that the C-5A uses a moderately swept wing, a tee-tail, and wing-pylon-mounted engines, the design requirements for forward and aft straight-in fuselage loading coupled with the provision of personnel accommodations, airdrop capability, and extremely high flotation, dictated fuselage and landing gear configurations which required an intensive effort to reduce aerodynamic drag to an absolute minimum level. This effort will be discussed. The design of the high lift system was dictated by extremely stringent airport requirements and the high wing loading necessary to achieve optimum matching of airframe and engine in the cruise regime.

Determination of the characteristics of arbitrary airfoil sections has mainly been accomplished in the past by wind tunnel tests. Due to the lengthy and often inaccurate computations involved, for the most part, theoretical analyses have been avoided. However, with the advent of high-speed computer techniques, more complicated methods which give better accuracy can now be used. By combining a number of subroutines which calculate various parts of the overall airfoil analysis, a program for accurately defining the characteristics of airfoil sections in two-dimensional, incompressible flow at arbitrary Reynolds numbers has been derived. In addition to defining the characteristics of a given section, the program may also be used to synthesize or design an airfoil which will have a desired pressure distribution. The effectiveness and useful speed of this program have been greatly enhanced with the use of computer graphic techniques.

A regenerable absorbent in solid granular form has been developed for the removal of carbon dioxide from air or other gases. The unique features of the absorbent are: (a) no pre-drying of the gas stream is necessary prior to carbon dioxide absorption, and (b) only moderate regeneration conditions are necessary to desorb CO2, for example, heating to 180 F and evacuating to a 40 mm vacuum. An operating laboratory prototype having a four-man capacity was built and tested, continuously removing 0.41 lb/hr of carbon dioxide at a 7.6 mm CO2 partial pressure. The system penalties for the unoptimized prototype were: 1. Absorbent weight - 30 lb (7.5 lb/man) 2. Structure and controls - 63 lb (total: 93 lb, or 23.3 lb/man) 3. Electrical power - 288 w (thermal power(electrical or sensible), 472 w; total 760 w, or 190 w/man) 4. Envelope volume - 14 × 24 × 33 in.

The paper reports basic adsorption data for CO2 and water vapor on molecular sieves and silica gel, a mathematical model used to predict the behavior of regenerative adsorption multibed systems, and prototype tests of an Apollo size system and comparison of this system with model predictions. The basic data include equilibrium isotherm data and non-equilibrium adsorption and desorption data taken in a small cross-section bed. The prototype tests were performed in a 6 by 6 by 6 in. adsorption bed that was packed with silica gel and molecular sieve.

Five joint designs in steel or aluminum are compared, using both a rubbery and a tough adhesive, cured at room temperature. Circular butts in simple and in torsional shear and tubular butts (“napkin rings”) in torsion are preferable to the ASTM D 1002 lap shear, as the adherend dimensions do not affect the measured strength. Thus the strength of a structure can be better assessed. Circular butts in tension (“poker chips”) are similarly suitable, and are as strong as in simple shear. The circular butts in torsion are stronger than the tubular butts, but the convenient simple-shear butts are nearly as strong. Strength dependence on strain rate and on adhesive thickness is compared with precision of measurement.

A simple and reliable concept for the collection, processing, disposal or storage of human waste products has been developed for application under conditions of weightlessness. Psychological acceptance is achieved by utilization of a hardware design permitting conventional earth-like procedures. Bag type containers are not used for collection and storage, thus manual handling of waste products and storage containers is not required. The system is capable of handling urine and fecal waste as well as Yomitus and food debris. The solids are vacuum dried to permit bacteriostatic storage and urine can be jettisoned to space.

Experimental results obtained with a continuous culture system for the cultivation of Hydrogenomonas eutropha for waste management in a life-support system indicate that a reliable and stable system can be designed under the present state-of-the-art. The present system provides for control of hydrogen, oxygen, carbon dioxide, pH, cell density, temperature, urea, and ammonia during growth. The culture system design is adaptable to operation in a zero-gravity field, and should be adaptable to integration with proposed water electrolysis and product recovery systems for waste management in an overall life support system.

An oxygen-producing water electrolysis cell with phosphoric acid electrolyte can operate on the water vapor in recirculated cabin air and accomplish concurrent dehumidification. The development of the concept over the past 3 years involved research to define the components of electrode overvoltage and design analysis to provide a small, lightweight unit to compensate for the electrolysis power. Theoretical equations based on electrochemistry, fluid dynamics, and heat and mass transfer correlate with the observed steady state operation obtained in extended testing of experimental cells for over 1000 hr. Data on electrode life, gas purity, and voltage characteristics combined with size, weight, and power estimates indicate that the new concept would be competitive with other methods of oxygen generation for advanced space missions. The recent satisfactory performance of a prototype module in an extended test of over 1000 hr is reviewed.

A novel prototype waste management unit for the collection, sampling, drying, and storage of fecal wastes in a life-support simulator, or aerospace flights has been designed, developed, and tested. The unit collects the feces, which are subsequently air dried at ambient temperature and pressure, and stored. The unit is designed for use in a weightless environment yet has the convenience of operation of an ordinary terrestrial toilet. Other design features include measures to prevent fecal contamination or odors from entering the space cabin, low power requirements, and minimum loss of cabin air overboard. Weight of the unit is about 50 lb.

The requirements for V/STOL aircraft introduce unique structural problems and make more severe those common to conventional vehicles. Propulsion modes requiring increased thrust during hover and their relative airframe locations are responsible for the major portion of the associated problems. Those problems which require first-order attention, such as design philosophy for fan-in-wing configurations to obtain optimum structural design are discussed. The solution of acoustic environment problems, such as noise attenuation and acoustic fatigue, are investigated. Likewise, the study of thermal problems, both internal and external, and their effect on structure is presented. The problem of debris damage due to the propulsion environment at ground hover is discussed showing the potential energy level of debris. Finally, the importance of structural weight/cost effectiveness is shown for V/STOL aircraft.

Atmospheric turbulence measured at low altitudes over rough terrain in high wind conditions is shown to be more severe than the turbulence previously measured in thunderstorms. The military requirement for large bomber and logistic airplanes to operate at low level thus will result in large weight and performance penalties unless some means to reduce structural loads is employed. By use of power spectral density techniques, it is shown that loads in low level turbulence can be reduced on large airplanes with an adequate stability augmentation system. This load reduction is sufficient to insure that large aircraft operating at low level will not be unduly penalized in performance.