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Flight tests have shown that, by means of improved displays and advanced control systems, it is possible to transform a typical light airplane into a flying machine that borders on being perfect from a handling-qualities standpoint. A flight-director display and an attitude-command control system used in combination transformed a vehicle with poor handling qualities during ILS approaches in turbulent air into a vehicle with extremely good handling qualities. The attitude-command control system also improved the ride qualities of the airplane. A rate-command control system was less beneficial than an attitude-command control system. Although this paper deals primarily with general aviation aircraft, the results presented pertain to other types of aircraft. Short-takeoff-and-landing (STOL) aircraft would be a natural application of the control systems because, as a result of their low speeds, they encounter many of the handling-qualities problems noted on light aircraft.

An interconnection between the roll and yaw control may function as a device for coordinating the two controls, or as a means for increasing the effective dihedral, or both. The coordinating function may be interpreted in terms of adjusting the overall level of aileron yaw; this can improve roll and yaw response to roll control inputs. The interconnect function of increasing effective dihedral is of questionable value, and some undesirable side effects might be avoided if it were not employed.

An altitude encoder enables an ATC transponder to report the altitude of the airplane to the controller, in addition to its identity and position. Several forms of altitude encoders have been designed. This paper describes a digital altitude encoder with only one moving part, almost zero friction, proper accuracy, and all solid-state components. In this encoder, frequency is the sensing parameter. Also covered are the Gray code and the Gillham code.

A new approach to airborne weather radar using a simple steerable phased-array antenna is presented. This antenna avoids the need for a dish of any kind and has no mechanical scanning device. It is inexpensive to manufacture, using micro-strip techniques throughout, and has an overall gain that is equal to or better than a dish of comparable size. It is electronically scanned at about 17 frames/s through a 90 deg total angle, producing a TV picture type display. The range, using an 8 kW peak power X-band transmitter and an inexpensive receiver, is greater than 90 miles. The model with beam width about 5 deg in the horizontal plane and 10 deg in the vertical plane fits entirely inside the wing of a Piper Cherokee. A “twin engine airplane” version with an 11 in array would have a 5 deg vertical beam width and 6 dB of additional loop gain which would permit the transmitter power to be reduced to 2 kW peak power for the 90 mile range.

The Garrett AiResearch Model TFE731-2 two-spool geared-fan jet engine rated at 3500 lb thrust is being developed to fulfill the need for a modern small powerplant in the general aviation marketplace. Rigorous preliminary design cycle optimization studies and the subsequent incorporation of proven component aerodynamic designs have resulted in an efficient, simple, and compact turbofan engine configuration. Highlights of the performance, mechanical reliability, and ecological aspects of the program are discussed. The engine is currently in the final stages of development with certification scheduled for April 1972.

This paper explores various ways that the aircraft industry can assist aviation technology schools in turning out graduates who can meet the industry's present and future requirements. Among the methods suggested are: active liaison between industry and schools, making company training materials and programs available to schools, inviting school personnel to seminars and company tours, establishing a network of communications between industry and schools, instituting a variety of cooperative work-study programs, and taking an active part in the training of technical education teachers.

Detroit Diesel Allison (formerly Allison) Division of General Motors has, since 1965, been developing and producing several models of its small model T63/250 gas turbine engine. This paper discusses the continuing engine program by identifying models and applications of both turboshaft helicopter engines and turboprop fixed wing aircraft powerplants. Progress in development of higher horsepower versions which improve the performance and utility of business aircraft is also discussed.

A survey was made of 162 engineering supervisors in 54 companies in the aircraft industry to determine to what extent their manpower needs have been filled by technology graduates. This paper reproduces the questionnaire, including a tabulation of the responses. The major findings were that such graduates are available, capable, somewhat inflexible, expendable, and promotable only to a point. In discussing the replies to the questionnaire, the author notes that in the present economic climate engineering departments are not operating under normal circumstances. Technologists are available, but are not being hired because of personnel cutbacks. He cites the situation as a challenge to produce a technologist who can provide support for engineering activity as well as adapt to changing job requirements. Areas in which technologists can make significant contributions, namely, design, project engineering, and electronics, are discussed in detail.

When technology emerged as a distinct area within the total technology spectrum following World War II, aeronautical technology came into being among 4y degree granting institutions. During the past decade, growth among these programs has been confined to expansion and refinement of existing programs, rather than a quantitative growth in the number of new programs being implemented. The proliferation of technician-oriented aeronautical programs among junior colleges came within the past decade. Programs vary from flight training activities provided on a flying club basis to in-depth aeronautical engineering technology curricula. Indiscriminate and universal application of the term “technology” to all aviation-related programs regardless of content or objective, has led to problems in the transfer of credits.

A different approach to aircraft passenger survival has been undertaken by the National Aeronautics and Space Administration and AVCO Corporation-that of shielding the passenger compartment by surrounding it with a fire resistant foam shell capable of protecting the occupants long enough for the fire to burn out, or for fire-fighting equipment to reach the aircraft and extinguish the fire. Application of the newly evolved intumescent material as a passive thermal control system to provide fire protection for remote or inaccessible dry bay regions and equipment bays is also discussed.

Tetra-Core is the name given to a fiber composite-material developed by the U.S. Army Aviation Materiel Laboratory, Fort Eustis, Va. This report discloses the initial studies conducted at the University of Kansas on Tetra-Core, including fabrication methods, analytical strength analyses, and experimental test results. The Tetra-Core composite is formed by stacking oriented, spaced-fiber lamina in a repeating -60, 0, +60 deg pattern. Layers are offset slightly as the stacking occurs to produce a tetrahedrally shaped element. An improved fabrication loom was conceived and tested. The loom concept is predicated on the fact that the intersection of two planes is a straight line. In the case of Tetra-Core, planes are formed by the buildup of lamina, intersecting to produce tetrahedrally shaped elements. The straight lines formed at these intersections are at an angle of 35 deg 15 min from the vertical.

This paper covers the properties of hardcoat anodizing as it applies to changing surface properties of aluminum so it can be used in areas heretofore prohibitive. Information concerning surface preparation, racking, equipment for the process, and post treatments is presented. Hardcoat anodizing changes the surface properties of aluminum so that it can now be used in many new applications. The process employs a refrigerated electrolyte maintained below 50 F, vigorous agitation, close control of processing conditions, and a higher current density than conventional anodizing. Specifics about the process at Cessna Aircraft Co. are presented, as is a discussion of racking, surface preparation, and post treatment. The properties of the anodize-coated aluminum and the resultant possible applications are also described.

A series of accelerated corrosion tests were conducted to study the relative rates of corrosion penetration into an adhesive bondline on clad and bare aluminum. Three different adhesive systems were tested. Both standard and corrosion-inhibiting primers were used with two of the adhesives. Aluminum alloys, 2024 bare and clad, 7075 bare and clad, 5052 and 3003 were used. The aluminum surfaces were prepared by chromic acid anodizing and by etching in a solution of sulfuric acid and sodium dichromate (FPL etch). The bonded panels were subjected to 30, 60, and 90 days exposure in a salt-spray cabinet. After exposure, the panels were tested for peel strength and were examined visually for extent of corrosion. The results of these tests indicate that the rate of bondline corrosion penetration is greater on the clad aluminum alloys and on 3003 than on the bare alloys tested.

The evolution of light aircraft design has tended to emphasize payload/range capabilities. A less understood but extremely meaningful area of design, the integration of cruise speed and low-speed flight aerodynamic optimization, is discussed here. High-lift technology has found broad application in large transport aircraft, but virtually none of this technology has been integrated into general aviation aircraft for reasons of cost, complexity of design, lack of low-cost manufacturing adaptability, etc. However, transport-category aerodynamic technology can be applied to general aviation and business aircraft. The application of extensive high-lift devices in conjunction with increased low-speed lift/drag ratio, and advanced airplane control systems to general aviation aircraft is reviewed. Parametric studies of pertinent wing aerodynamic variables were performed for a typical twin-engine propeller aircraft.

Recent experimental developments in military programs in aircraft quieting are reviewed in this paper, with suggestions on acoustic technology applications appropriate to general aviation. Comments are offered on the possible impact of developing noise abatement concerns, requirements, and legislation on general aviation. Potentially productive design tradeoff studies necessary to ensure minimum cost and an acceptable level of performance in the field of commercial light aircraft design are suggested. Reduction in the external acoustic noise signature of light piston-engine aircraft may logically be sought in the area of propulsion system design.

To overcome the most serious deficiency in fiber-reinforced composite materials a three-dimensional, continuously woven material has been developed. To demonstrate the feasibility of the new weave pattern, a 0.3 in thick fabric was woven with 12-end S-glass roving and impregnated with Epon 828 epoxy resin using curing agent Z. A 24 harness semiautomatic loom was used to produce the fabric. Tension tests were conducted on the material in both the weave and transverse directions. The material exhibited maximum tensile strength of 47,000 psi and 64,000 psi in the weave and transverse directions, respectively. The elastic moduli were 2,640,000 and 3,220,000 psi, respectively. Compression tests were conducted in the weave (longitudinal), transverse, and thickness directions. The ultimate strengths in compression were 39,000, 52,000, and 71,000 psi, respectively. The elastic moduli in compression were 2,820,000, 3,410,000, and 1,240,000 psi in the three respective principal directions.

Pilots have to read and analyze much flight information. Conditions that require instant action can be instantly recognized by the use of indicator lights. These lights are grouped into annunciator systems, which have changed from simple, single indicator warnings to complex, multichannel systems. These systems provide an analysis of significant conditions of the aircraft and warn of any changes in this condition. This paper discusses the categories of annunciator indicators, circuit requirements, circuit design, additional input circuits, and application.

The purpose of this paper is to explain how the following challenging targets have been achieved: large cabin volume with a cruise speed above 400 knots using only limited thrust; short field capability with simple high-lift devices; and versatility with a unique basic version. In each case a carefully balanced choice between several technical solutions was necessary in order to bring on the market a moderately priced aircraft.

This paper addresses the three questions: “Is V/STOL capability economically viable for business aircraft, and if so, how does the viability depend on the aircraft concept?”; “How is a V/STOL concept chosen to match a given mission, and what are some of the promising V/STOL concepts for future business aircraft?”; and “What unique operational requirements are likely to be imposed on users of future V/STOL business aircraft?” A cost-benefit analysis is presented which indicates that a VTOL business aircraft would be more viable economically than a contemporary turbine-powered business aircraft. The combinations of traveler's time value and trip distance for which each aircraft dominates is shown. A discussion is presented on the significance of disc loading as it relates to V/STOL concept application. Preliminary design configuration studies for three different business-aircraft-sized V/STOLs, using three concepts covering a range of disc loading, are presented as examples.

Development of engine-vehicle prototypes for low emissions and optimum fuel control characteristics has been facilitated through use of a computerized emissions test system. Simultaneous on-line sampling of exhaust species concentrations, fuel consumption, spark advance, pressures, and temperatures provides both graphical and computed outputs of several vehicle parameters that are important to development programs. On-line display of vehicle air-fuel ratio is continuously supplied. Either of two federal driving cycles (or any random driving schedule) may be employed. Dynamic calibration, range sensing, and zero-drift correction keep operator interaction and errors to a minimum. Capability for reprocessing, plotting, and/or patching stored data provides increased computational flexibility.