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Technical Paper

Reduced Vertical Separation Minimum for General Aviation Aircraft

Documented herein are the methods utilized to meet the performance requirements for operation in RVSM airspace. The test aircraft was equipped with an instrumented static system and a trailing cone static reference. The trailing cone was calibrated in-flight using laser range and radio altitude tower fly-by methods. Determination of the static source error and development of the static source error correction was accomplished on the instrumented aircraft. Verification of RVSM performance was accomplished on a standard production aircraft utilizing the instrumented aircraft as a pace. Additionally, test data were also obtained with perturbations on the skin near the static ports. The measured pressure changes were correlated with computational predictions. These data were used to develop skin waviness tolerances for the area around the static ports.
Technical Paper

Environmental Durability of Aircraft Aluminum Alloy Skin Materials

This paper compares the environmental durability of currently used as well as some of the potential aircraft aluminum alloy skin materials. A simple test was developed to evaluate the environmental durability by simultaneous application of fatigue loads and aerated salt water attack. Alclad alloys showed excellent resistance to corrosion fatigue. On the other hand, 7475 alloy and new potential material 6013 alloy experienced inter-granular corrosion at the fatigue crack origin area. The test results also indicated the significance of corrosion preventive coatings to increase the age of aircraft.
Technical Paper

Flight Test Investigations of a Wing Designed for Natural Laminar Flow

Full scale flight tests of a wing designed for natural laminar flow (NLF) have provided insight into the aerodynamic characteristics of the airfoil used (NLF(1)-0414F), and into the effects of transition location on airfoil lift, drag, pitching moment and overall aircraft performance. Results of these tests help answer questions pertaining to the development of aircraft using NLF airfoils such as the one tested. These data also provide comparisons of predictions based on computational and wind tunnel test methods. Instrumentation methods used to gather data during these tests include flush mounted airfoil pressure orifices, hot film anemometers and a wing mounted integrating wake rake.
Technical Paper

Effect of an Isolated Shell on Interior Noise levels in a Turboprop Aircraft

A noise control strategy for a small twin engine turboprop aircraft is evaluated. The noise control strategy consisted of a composite shell suspended inside the aircraft on isolation mounts. The evaluation consisted of a ground test program on component panels to select the shell material and a flight test program on the aircraft with and without the interior shell installed. Results from both phases are presented.
Technical Paper

Experimental Verification of Program KRASH-A Mathematical Model for General Aviation Structural Crash Dynamics

The results of four fully instrumented, full-scale crash tests involving a single-engine, high-wing light airplane are described herein. The tests were performed under a contract sponsored by the Federal Aviation Administration. The range of impact conditions included initial airplane roll and/or yaw, a nose-down attitude, a flared nose-up attitude and impacts onto a rigid (concrete) and a flexible (soil) surface. Photographs are presented showing the impact conditions, as well as some typical postcrash damage. The crash test models, analyzed using digital computer program KRASH, are described. Typical analysis versus test correlation results as well as a summary correlation for all four crash tests are presented. The application of Program KRASH to assess structural design concepts with regard to crash dynamics characteristics is briefly described.
Technical Paper

Some Special Investigation Areas in Light Aircraft Flutter

A brief description is given of one approach taken by a manufacturer of light business and personal aircraft to the flutter analysis of propeller whirl flutter, twin-boom aircraft, T-tail configuration, servo tabs, and all-moving tail. Effects of structural variations that may occur in the service life of an aircraft are presented, and the effect of ice formation on control surfaces is discussed.
Technical Paper

Weather Radar for Light Centerline Thrust Aircraft

An airborne weather radar installation has been developed for light centerline thrust aircraft. A pod was developed and tested to attach to the underside of the wing and provide a location for a light weight antenna-receiver-transmitter unit. The offering of this installation to operators of these aircraft provides additional capability in the detection and avoidance of significant weather systems.
Technical Paper

General Aviation Fatigue Loads-A Comparison of Analytical and Recorded Spectra

Measured fatigue load spectra (in terms of stress exceedance data) for two business aircraft operations are compared to the analytical spectra. The in-service load measuring procedure using mechanical strain gages is presented. The analytical methods, and the conclusions which may be drawn from the comparisons are discussed.
Technical Paper

The Influence of Design Parameters on Light Propeller Aircraft Noise

Through research and test work, the aircraft industry has gained a better knowledge of the design parameters which influence the noise produced by light propeller driven aircraft. The parameters found to have a major affect on the noise include: propeller tip speed, propeller blade tip thickness, and engine exhaust system characteristics. To date, many special design considerations such as geared or shrouded propellers have not proven effective in reducing noise levels. When developing an aircraft for reduced noise, its cost, performance, and utility must be considered.
Technical Paper

Human Factors Evaluation of Aircraft Engine Instrument Displays

Relative merits of three types of aircraft engine instruments were examined in respect to aircraft changing conditions. The experimental design considered interference, workload, age, and experience. Instruments were comparable so far as instrument size and characteristics would allow. Experimental results and comments indicated the experimental apparatus and failure parameters were comparable to actual aircraft situations. It was discovered that vertical-scale engine instruments required less recognition and scan time. Age and flight experience were not significant in this experimental design.